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Visual C++

t3dlib10.cpp：源码内容

sl+=dsdyl;
tl+=dtdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if clip
else
{
// non-clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
si = sl + FIXP16_ROUND_UP;
ti = tl + FIXP16_ROUND_UP;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
ds = (sr - sl)/dx;
dt = (tr - tl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
ds = (sr - sl);
dt = (tr - tl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// write textel assume 5.6.5
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// get textel first
textel = textmap[(si >> FIXP16_SHIFT) + ((ti >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with gouraud shading
r_textel*=ui;
g_textel*=vi;
b_textel*=wi;
// finally write pixel, note that we did the math such that the results are r*32, g*64, b*32
// hence we need to divide the results by 32,64,32 respetively, BUT since we need to shift
// the results to fit into the destination 5.6.5 word, we can take advantage of the shifts
// and they all cancel out for the most part, but we will need logical anding, we will do
// it later when we optimize more...
screen_ptr[xi] = ((b_textel >> (FIXP16_SHIFT+8)) +
((g_textel >> (FIXP16_SHIFT+8)) << 5) +
((r_textel >> (FIXP16_SHIFT+8)) << 11));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
si+=ds;
ti+=dt;
} // end for xi
// interpolate u,v,w,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
sl+=dsdyl;
tl+=dtdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if non-clipped
} // end if
else
if (tri_type==TRI_TYPE_GENERAL)
{
// first test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// pre-test y clipping status
if (y1 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
dsdyl = ((ts2 - ts1) << FIXP16_SHIFT)/dyl;
dtdyl = ((tt2 - tt1) << FIXP16_SHIFT)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
dsdyr = ((ts2 - ts0) << FIXP16_SHIFT)/dyr;
dtdyr = ((tt2 - tt0) << FIXP16_SHIFT)/dyr;
// compute overclip
dyr = (min_clip_y - y0);
dyl = (min_clip_y - y1);
// computer new LHS starting values
xl = dxdyl*dyl + (x1 << FIXP16_SHIFT);
ul = dudyl*dyl + (tu1 << FIXP16_SHIFT);
vl = dvdyl*dyl + (tv1 << FIXP16_SHIFT);
wl = dwdyl*dyl + (tw1 << FIXP16_SHIFT);
zl = dzdyl*dyl + (tz1 << 0);
sl = dsdyl*dyl + (ts1 << FIXP16_SHIFT);
tl = dtdyl*dyl + (tt1 << FIXP16_SHIFT);
// compute new RHS starting values
xr = dxdyr*dyr + (x0 << FIXP16_SHIFT);
ur = dudyr*dyr + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dyr + (tv0 << FIXP16_SHIFT);
wr = dwdyr*dyr + (tw0 << FIXP16_SHIFT);
zr = dzdyr*dyr + (tz0 << 0);
sr = dsdyr*dyr + (ts0 << FIXP16_SHIFT);
tr = dtdyr*dyr + (tt0 << FIXP16_SHIFT);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr > dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(dsdyl,dsdyr,temp);
SWAP(dtdyl,dtdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(sl,sr,temp);
SWAP(tl,tr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
SWAP(ts1,ts2,temp);
SWAP(tt1,tt2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
if (y0 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw1 - tw0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
dsdyl = ((ts1 - ts0) << FIXP16_SHIFT)/dyl;
dtdyl = ((tt1 - tt0) << FIXP16_SHIFT)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
dsdyr = ((ts2 - ts0) << FIXP16_SHIFT)/dyr;
dtdyr = ((tt2 - tt0) << FIXP16_SHIFT)/dyr;
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
wl = dwdyl*dy + (tw0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
sl = dsdyl*dy + (ts0 << FIXP16_SHIFT);
tl = dtdyl*dy + (tt0 << FIXP16_SHIFT);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv0 << FIXP16_SHIFT);
wr = dwdyr*dy + (tw0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
sr = dsdyr*dy + (ts0 << FIXP16_SHIFT);
tr = dtdyr*dy + (tt0 << FIXP16_SHIFT);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(dsdyl,dsdyr,temp);
SWAP(dtdyl,dtdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(sl,sr,temp);
SWAP(tl,tr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
SWAP(ts1,ts2,temp);
SWAP(tt1,tt2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
{
// no initial y clipping
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw1 - tw0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
dsdyl = ((ts1 - ts0) << FIXP16_SHIFT)/dyl;
dtdyl = ((tt1 - tt0) << FIXP16_SHIFT)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
dsdyr = ((ts2 - ts0) << FIXP16_SHIFT)/dyr;
dtdyr = ((tt2 - tt0) << FIXP16_SHIFT)/dyr;
// no clipping y
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
wl = (tw0 << FIXP16_SHIFT);
zl = (tz0 << 0);
sl = (ts0 << FIXP16_SHIFT);
tl = (tt0 << FIXP16_SHIFT);
ur = (tu0 << FIXP16_SHIFT);
vr = (tv0 << FIXP16_SHIFT);
wr = (tw0 << FIXP16_SHIFT);
zr = (tz0 << 0);
sr = (ts0 << FIXP16_SHIFT);
tr = (tt0 << FIXP16_SHIFT);
// set starting y
ystart = y0;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(dsdyl,dsdyr,temp);
SWAP(dtdyl,dtdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(sl,sr,temp);
SWAP(tl,tr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
SWAP(ts1,ts2,temp);
SWAP(tt1,tt2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end else
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
si = sl + FIXP16_ROUND_UP;
ti = tl + FIXP16_ROUND_UP;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
ds = (sr - sl)/dx;
dt = (tr - tl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
ds = (sr - sl);
dt = (tr - tl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
wi+=dx*dw;
zi+=dx*dz;
si+=dx*ds;
ti+=dx*dt;
// set x to left clip edge
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// write textel assume 5.6.5
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// get textel first
textel = textmap[(si >> FIXP16_SHIFT) + ((ti >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with gouraud shading
r_textel*=ui;
g_textel*=vi;
b_textel*=wi;
// finally write pixel, note that we did the math such that the results are r*32, g*64, b*32
// hence we need to divide the results by 32,64,32 respetively, BUT since we need to shift
// the results to fit into the destination 5.6.5 word, we can take advantage of the shifts
// and they all cancel out for the most part, but we will need logical anding, we will do
// it later when we optimize more...
screen_ptr[xi] = ((b_textel >> (FIXP16_SHIFT+8)) +
((g_textel >> (FIXP16_SHIFT+8)) << 5) +
((r_textel >> (FIXP16_SHIFT+8)) << 11));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
si+=ds;
ti+=dt;
} // end for xi
// interpolate u,v,w,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
sl+=dsdyl;
tl+=dtdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
dsdyl = ((ts2 - ts1) << FIXP16_SHIFT)/dyl;
dtdyl = ((tt2 - tt1) << FIXP16_SHIFT)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
wl = (tw1 << FIXP16_SHIFT);
zl = (tz1 << 0);
sl = (ts1 << FIXP16_SHIFT);
tl = (tt1 << FIXP16_SHIFT);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
sl+=dsdyl;
tl+=dtdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw1 - tw2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
dsdyr = ((ts1 - ts2) << FIXP16_SHIFT)/dyr;
dtdyr = ((tt1 - tt2) << FIXP16_SHIFT)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
wr = (tw2 << FIXP16_SHIFT);
zr = (tz2 << 0);
sr = (ts2 << FIXP16_SHIFT);
tr = (tt2 << FIXP16_SHIFT);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
} // end else
} // end if
} // end for y
} // end if
else
{
// no x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
si = sl + FIXP16_ROUND_UP;
ti = tl + FIXP16_ROUND_UP;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
ds = (sr - sl)/dx;
dt = (tr - tl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
ds = (sr - sl);
dt = (tr - tl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// write textel assume 5.6.5
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// get textel first
textel = textmap[(si >> FIXP16_SHIFT) + ((ti >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with gouraud shading
r_textel*=ui;
g_textel*=vi;
b_textel*=wi;
// finally write pixel, note that we did the math such that the results are r*32, g*64, b*32
// hence we need to divide the results by 32,64,32 respetively, BUT since we need to shift
// the results to fit into the destination 5.6.5 word, we can take advantage of the shifts
// and they all cancel out for the most part, but we will need logical anding, we will do
// it later when we optimize more...
screen_ptr[xi] = ((b_textel >> (FIXP16_SHIFT+8)) +
((g_textel >> (FIXP16_SHIFT+8)) << 5) +
((r_textel >> (FIXP16_SHIFT+8)) << 11));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
si+=ds;
ti+=dt;
} // end for xi
// interpolate u,v,w,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
sl+=dsdyl;
tl+=dtdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
dsdyl = ((ts2 - ts1) << FIXP16_SHIFT)/dyl;
dtdyl = ((tt2 - tt1) << FIXP16_SHIFT)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
wl = (tw1 << FIXP16_SHIFT);
zl = (tz1 << 0);
sl = (ts1 << FIXP16_SHIFT);
tl = (tt1 << FIXP16_SHIFT);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
sl+=dsdyl;
tl+=dtdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw1 - tw2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
dsdyr = ((ts1 - ts2) << FIXP16_SHIFT)/dyr;
dtdyr = ((tt1 - tt2) << FIXP16_SHIFT)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
wr = (tw2 << FIXP16_SHIFT);
zr = (tz2 << 0);
sr = (ts2 << FIXP16_SHIFT);
tr = (tt2 << FIXP16_SHIFT);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
sr+=dsdyr;
tr+=dtdyr;
} // end else
} // end if
} // end for y
} // end else
} // end if
} // end Draw_Textured_TriangleGSINVZB_16
///////////////////////////////////////////////////////////////////////////////
void Draw_Gouraud_TriangleINVZB_16(POLYF4DV2_PTR face, // ptr to face
UCHAR *_dest_buffer, // pointer to video buffer
int mem_pitch, // bytes per line, 320, 640 etc.
UCHAR *_zbuffer, // pointer to z-buffer
int zpitch) // bytes per line of zbuffer
{
// this function draws a gouraud shaded polygon, based on the affine texture mapper, instead
// of interpolating the texture coordinates, we simply interpolate the (R,G,B) values across
// the polygons, I simply needed at another interpolant, I have mapped u->red, v->green, w->blue
// also a new interpolant for z buffering has been added
int v0=0,
v1=1,
v2=2,
temp=0,
tri_type = TRI_TYPE_NONE,
irestart = INTERP_LHS;
int dx,dy,dyl,dyr, // general deltas
u,v,w,z,
du,dv,dw,dz,
xi,yi, // the current interpolated x,y
ui,vi,wi,zi, // the current interpolated u,v,w,z
index_x,index_y, // looping vars
x,y, // hold general x,y
xstart,
xend,
ystart,
yrestart,
yend,
xl,
dxdyl,
xr,
dxdyr,
dudyl,
ul,
dvdyl,
vl,
dwdyl,
wl,
dzdyl,
zl,
dudyr,
ur,
dvdyr,
vr,
dwdyr,
wr,
dzdyr,
zr;
int x0,y0,tu0,tv0,tw0,tz0, // cached vertices
x1,y1,tu1,tv1,tw1,tz1,
x2,y2,tu2,tv2,tw2,tz2;
int r_base0, g_base0, b_base0,
r_base1, g_base1, b_base1,
r_base2, g_base2, b_base2;
USHORT *screen_ptr = NULL,
*screen_line = NULL,
*textmap = NULL,
*dest_buffer = (USHORT *)_dest_buffer;
UINT *z_ptr = NULL,
*zbuffer = (UINT *)_zbuffer;
#ifdef DEBUG_ON
// track rendering stats
debug_polys_rendered_per_frame++;
#endif
// adjust memory pitch to words, divide by 2
mem_pitch >>=1;
// adjust zbuffer pitch for 32 bit alignment
zpitch >>= 2;
// apply fill convention to coordinates
face->tvlist[0].x = (int)(face->tvlist[0].x+0.5);
face->tvlist[0].y = (int)(face->tvlist[0].y+0.5);
face->tvlist[1].x = (int)(face->tvlist[1].x+0.5);
face->tvlist[1].y = (int)(face->tvlist[1].y+0.5);
face->tvlist[2].x = (int)(face->tvlist[2].x+0.5);
face->tvlist[2].y = (int)(face->tvlist[2].y+0.5);
// first trivial clipping rejection tests
if (((face->tvlist[0].y < min_clip_y) &&
(face->tvlist[1].y < min_clip_y) &&
(face->tvlist[2].y < min_clip_y)) ||
((face->tvlist[0].y > max_clip_y) &&
(face->tvlist[1].y > max_clip_y) &&
(face->tvlist[2].y > max_clip_y)) ||
((face->tvlist[0].x < min_clip_x) &&
(face->tvlist[1].x < min_clip_x) &&
(face->tvlist[2].x < min_clip_x)) ||
((face->tvlist[0].x > max_clip_x) &&
(face->tvlist[1].x > max_clip_x) &&
(face->tvlist[2].x > max_clip_x)))
return;
// sort vertices
if (face->tvlist[v1].y < face->tvlist[v0].y)
{SWAP(v0,v1,temp);}
if (face->tvlist[v2].y < face->tvlist[v0].y)
{SWAP(v0,v2,temp);}
if (face->tvlist[v2].y < face->tvlist[v1].y)
{SWAP(v1,v2,temp);}
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v0].y, face->tvlist[v1].y))
{
// set triangle type
tri_type = TRI_TYPE_FLAT_TOP;
// sort vertices left to right
if (face->tvlist[v1].x < face->tvlist[v0].x)
{SWAP(v0,v1,temp);}
} // end if
else
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v1].y, face->tvlist[v2].y) )
{
// set triangle type
tri_type = TRI_TYPE_FLAT_BOTTOM;
// sort vertices left to right
if (face->tvlist[v2].x < face->tvlist[v1].x)
{SWAP(v1,v2,temp);}
} // end if
else
{
// must be a general triangle
tri_type = TRI_TYPE_GENERAL;
} // end else
// assume 5.6.5 format -- sorry!
// we can't afford a function call in the inner loops, so we must write
// two hard coded versions, if we want support for both 5.6.5, and 5.5.5
_RGB565FROM16BIT(face->lit_color[v0], &r_base0, &g_base0, &b_base0);
_RGB565FROM16BIT(face->lit_color[v1], &r_base1, &g_base1, &b_base1);
_RGB565FROM16BIT(face->lit_color[v2], &r_base2, &g_base2, &b_base2);
// scale to 8 bit
r_base0 <<= 3;
g_base0 <<= 2;
b_base0 <<= 3;
// scale to 8 bit
r_base1 <<= 3;
g_base1 <<= 2;
b_base1 <<= 3;
// scale to 8 bit
r_base2 <<= 3;
g_base2 <<= 2;
b_base2 <<= 3;
// extract vertices for processing, now that we have order
x0 = (int)(face->tvlist[v0].x+0.0);
y0 = (int)(face->tvlist[v0].y+0.0);
tz0 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v0].z+0.5);
tu0 = r_base0;
tv0 = g_base0;
tw0 = b_base0;
x1 = (int)(face->tvlist[v1].x+0.0);
y1 = (int)(face->tvlist[v1].y+0.0);
tz1 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v1].z+0.5);
tu1 = r_base1;
tv1 = g_base1;
tw1 = b_base1;
x2 = (int)(face->tvlist[v2].x+0.0);
y2 = (int)(face->tvlist[v2].y+0.0);
tz2 = (1 <<FIXP28_SHIFT) / (int)(face->tvlist[v2].z+0.5);
tu2 = r_base2;
tv2 = g_base2;
tw2 = b_base2;
// degenerate triangle
if ( ((x0 == x1) && (x1 == x2)) || ((y0 == y1) && (y1 == y2)))
return;
// set interpolation restart value
yrestart = y1;
// what kind of triangle
if (tri_type & TRI_TYPE_FLAT_MASK)
{
if (tri_type == TRI_TYPE_FLAT_TOP)
{
// compute all deltas
dy = (y2 - y0);
dxdyl = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu2 - tu0) << FIXP16_SHIFT)/dy;
dvdyl = ((tv2 - tv0) << FIXP16_SHIFT)/dy;
dwdyl = ((tw2 - tw0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz2 - tz0) << 0)/dy;
dxdyr = ((x2 - x1) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu1) << FIXP16_SHIFT)/dy;
dvdyr = ((tv2 - tv1) << FIXP16_SHIFT)/dy;
dwdyr = ((tw2 - tw1) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz1) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
wl = dwdyl*dy + (tw0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x1 << FIXP16_SHIFT);
ur = dudyr*dy + (tu1 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv1 << FIXP16_SHIFT);
wr = dwdyr*dy + (tw1 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz1 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x1 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
wl = (tw0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu1 << FIXP16_SHIFT);
vr = (tv1 << FIXP16_SHIFT);
wr = (tw1 << FIXP16_SHIFT);
zr = (tz1 << 0);
// set starting y
ystart = y0;
} // end else
} // end if flat top
else
{
// must be flat bottom
// compute all deltas
dy = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dy;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dy;
dwdyl = ((tw1 - tw0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz1 - tz0) << 0)/dy;
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dy;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dy;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz0) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
wl = dwdyl*dy + (tw0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv0 << FIXP16_SHIFT);
wr = dwdyr*dy + (tw0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
wl = (tw0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu0 << FIXP16_SHIFT);
vr = (tv0 << FIXP16_SHIFT);
wr = (tw0 << FIXP16_SHIFT);
zr = (tz0 << 0);
// set starting y
ystart = y0;
} // end else
} // end else flat bottom
// test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
wi+=dx*dw;
zi+=dx*dz;
// reset vars
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
screen_ptr[xi] = ((ui >> (FIXP16_SHIFT+3)) << 11) +
((vi >> (FIXP16_SHIFT+2)) << 5) +
(wi >> (FIXP16_SHIFT+3));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,w,z
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
} // end for xi
// interpolate u,v,w,z,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
} // end for y
} // end if clip
else
{
// non-clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel 5.6.5
screen_ptr[xi] = ((ui >> (FIXP16_SHIFT+3)) << 11) +
((vi >> (FIXP16_SHIFT+2)) << 5) +
(wi >> (FIXP16_SHIFT+3));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,w,z
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
} // end for xi
// interpolate u,v,w,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
} // end for y
} // end if non-clipped
} // end if
else
if (tri_type==TRI_TYPE_GENERAL)
{
// first test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// pre-test y clipping status
if (y1 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dyr = (min_clip_y - y0);
dyl = (min_clip_y - y1);
// computer new LHS starting values
xl = dxdyl*dyl + (x1 << FIXP16_SHIFT);
ul = dudyl*dyl + (tu1 << FIXP16_SHIFT);
vl = dvdyl*dyl + (tv1 << FIXP16_SHIFT);
wl = dwdyl*dyl + (tw1 << FIXP16_SHIFT);
zl = dzdyl*dyl + (tz1 << 0);
// compute new RHS starting values
xr = dxdyr*dyr + (x0 << FIXP16_SHIFT);
ur = dudyr*dyr + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dyr + (tv0 << FIXP16_SHIFT);
wr = dwdyr*dyr + (tw0 << FIXP16_SHIFT);
zr = dzdyr*dyr + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr > dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
if (y0 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw1 - tw0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
wl = dwdyl*dy + (tw0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv0 << FIXP16_SHIFT);
wr = dwdyr*dy + (tw0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
{
// no initial y clipping
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw1 - tw0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw2 - tw0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// no clipping y
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
wl = (tw0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu0 << FIXP16_SHIFT);
vr = (tv0 << FIXP16_SHIFT);
wr = (tw0 << FIXP16_SHIFT);
zr = (tz0 << 0);
// set starting y
ystart = y0;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dwdyl,dwdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(wl,wr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tw1,tw2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end else
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
wi+=dx*dw;
zi+=dx*dz;
// set x to left clip edge
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
screen_ptr[xi] = ((ui >> (FIXP16_SHIFT+3)) << 11) +
((vi >> (FIXP16_SHIFT+2)) << 5) +
(wi >> (FIXP16_SHIFT+3));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,w,z
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
} // end for xi
// interpolate u,v,w,z,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
wl = (tw1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw1 - tw2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
wr = (tw2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end if
else
{
// no x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w,z interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
wi = wl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dw = (wr - wl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dw = (wr - wl);
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
screen_ptr[xi] = ((ui >> (FIXP16_SHIFT+3)) << 11) +
((vi >> (FIXP16_SHIFT+2)) << 5) +
(wi >> (FIXP16_SHIFT+3));
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,w,z
ui+=du;
vi+=dv;
wi+=dw;
zi+=dz;
} // end for xi
// interpolate u,v,w,x,z along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dwdyl = ((tw2 - tw1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
wl = (tw1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
wl+=dwdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dwdyr = ((tw1 - tw2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
wr = (tw2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
wr+=dwdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end else
} // end if
} // end Draw_Gouraud_TriangleINVZB_16
///////////////////////////////////////////////////////////////////////////////
void Draw_RENDERLIST4DV2_SolidINVZB_16(RENDERLIST4DV2_PTR rend_list,
UCHAR *video_buffer,
int lpitch,
UCHAR *zbuffer,
int zpitch)
{
// 16-bit version
// this function "executes" the render list or in other words
// draws all the faces in the list, the function will call the
// proper rasterizer based on the lighting model of the polygons
POLYF4DV2 face; // temp face used to render polygon
// at this point, all we have is a list of polygons and it's time
// to draw them
for (int poly=0; poly < rend_list->num_polys; poly++)
{
// render this polygon if and only if it's not clipped, not culled,
// active, and visible, note however the concecpt of "backface" is
// irrelevant in a wire frame engine though
if (!(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_ACTIVE) ||
(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_CLIPPED ) ||
(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_BACKFACE) )
continue; // move onto next poly
// need to test for textured first, since a textured poly can either
// be emissive, or flat shaded, hence we need to call different
// rasterizers
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_TEXTURE)
{
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.tvlist[0].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[0].u0;
face.tvlist[0].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[0].v0;
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.tvlist[1].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[1].u0;
face.tvlist[1].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[1].v0;
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
face.tvlist[2].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[2].u0;
face.tvlist[2].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[2].v0;
// test if this is a mipmapped polygon?
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_MIPMAP)
{
// determine mip level for this polygon
int miplevel = (6*rend_list->poly_ptrs[poly]->tvlist[0].z/2000);
if (miplevel > 6)
miplevel = 6;
face.texture = ((BITMAP_IMAGE_PTR *)(rend_list->poly_ptrs[poly]->texture))[miplevel];
for (int ts = 0; ts < miplevel; ts++)
{
face.tvlist[0].u0*=.5;
face.tvlist[0].v0*=.5;
face.tvlist[1].u0*=.5;
face.tvlist[1].v0*=.5;
face.tvlist[2].u0*=.5;
face.tvlist[2].v0*=.5;
} // end for
} // end if
else
{
// assign the texture without change
face.texture = rend_list->poly_ptrs[poly]->texture;
} // end if
// is this a plain emissive texture?
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_CONSTANT)
{
// draw the textured triangle as emissive
Draw_Textured_TriangleINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end if
else
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_FLAT)
{
// draw as flat shaded
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
//if (avg_z > MIN_PERSPECTIVE_CORRECT_DIST)
Draw_Textured_TriangleFSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
//else
//Draw_Textured_PerspectiveLP_Triangle_FSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end else if
else
{
// must be gouraud POLY4DV2_ATTR_SHADE_MODE_GOURAUD
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
face.lit_color[1] = rend_list->poly_ptrs[poly]->lit_color[1];
face.lit_color[2] = rend_list->poly_ptrs[poly]->lit_color[2];
Draw_Textured_TriangleGSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end else
} // end if
else
if ((rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_FLAT) ||
(rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_CONSTANT) )
{
// draw as constant shaded
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
// draw the triangle with basic flat rasterizer
Draw_Triangle_2DINVZB_16(&face, video_buffer, lpitch, zbuffer, zpitch);
} // end if
else
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_GOURAUD)
{
// {andre take advantage of the data structures later..}
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.lit_color[1] = rend_list->poly_ptrs[poly]->lit_color[1];
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
face.lit_color[2] = rend_list->poly_ptrs[poly]->lit_color[2];
// draw the gouraud shaded triangle
Draw_Gouraud_TriangleINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end if gouraud
} // end for poly
} // end Draw_RENDERLIST4DV2_SolidINVZB_16
///////////////////////////////////////////////////////////////////////////////////////////
void Draw_RENDERLIST4DV2_Hybrid_Textured_SolidINVZB_16(RENDERLIST4DV2_PTR rend_list,
UCHAR *video_buffer,
int lpitch,
UCHAR *zbuffer,
int zpitch,
float dist1, float dist2)
{
// 16-bit version
// this function "executes" the render list or in other words
// draws all the faces in the list, the function will call the
// proper rasterizer based on the lighting model of the polygons
// testing function only for demo, place maxperspective distance
// into dist1, and max linear into dist2, after dist2 everything
// will be affine
POLYF4DV2 face; // temp face used to render polygon
// at this point, all we have is a list of polygons and it's time
// to draw them
for (int poly=0; poly < rend_list->num_polys; poly++)
{
// render this polygon if and only if it's not clipped, not culled,
// active, and visible, note however the concecpt of "backface" is
// irrelevant in a wire frame engine though
if (!(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_ACTIVE) ||
(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_CLIPPED ) ||
(rend_list->poly_ptrs[poly]->state & POLY4DV2_STATE_BACKFACE) )
continue; // move onto next poly
// need to test for textured first, since a textured poly can either
// be emissive, or flat shaded, hence we need to call different
// rasterizers
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_TEXTURE)
{
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.tvlist[0].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[0].u0;
face.tvlist[0].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[0].v0;
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.tvlist[1].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[1].u0;
face.tvlist[1].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[1].v0;
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
face.tvlist[2].u0 = (float)rend_list->poly_ptrs[poly]->tvlist[2].u0;
face.tvlist[2].v0 = (float)rend_list->poly_ptrs[poly]->tvlist[2].v0;
// test if this is a mipmapped polygon?
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_MIPMAP)
{
// determine mip level for this polygon
int miplevel = (6*rend_list->poly_ptrs[poly]->tvlist[0].z/2000);
if (miplevel > 6)
miplevel = 6;
face.texture = ((BITMAP_IMAGE_PTR *)(rend_list->poly_ptrs[poly]->texture))[miplevel];
for (int ts = 0; ts < miplevel; ts++)
{
face.tvlist[0].u0*=.5;
face.tvlist[0].v0*=.5;
face.tvlist[1].u0*=.5;
face.tvlist[1].v0*=.5;
face.tvlist[2].u0*=.5;
face.tvlist[2].v0*=.5;
} // end for
} // end if
else
{
// assign the texture without change
face.texture = rend_list->poly_ptrs[poly]->texture;
} // end if
float avg_z = 0.33*(rend_list->poly_ptrs[poly]->tvlist[0].z +
rend_list->poly_ptrs[poly]->tvlist[1].z +
rend_list->poly_ptrs[poly]->tvlist[2].z );
// is this a plain emissive texture?
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_CONSTANT)
{
// draw the textured triangle as emissive
if (avg_z < dist1)
Draw_Textured_Perspective_Triangle_INVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
else
if (avg_z > dist1 && avg_z < dist2)
Draw_Textured_PerspectiveLP_Triangle_INVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
else
Draw_Textured_TriangleINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end if
else
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_FLAT)
{
// draw as flat shaded
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
if (avg_z < dist1)
Draw_Textured_Perspective_Triangle_FSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
else
if (avg_z > dist1 && avg_z < dist2)
Draw_Textured_PerspectiveLP_Triangle_FSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
else
Draw_Textured_TriangleFSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end else if
else
{
// must be gouraud POLY4DV2_ATTR_SHADE_MODE_GOURAUD
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
face.lit_color[1] = rend_list->poly_ptrs[poly]->lit_color[1];
face.lit_color[2] = rend_list->poly_ptrs[poly]->lit_color[2];
Draw_Textured_TriangleGSINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end else
} // end if
else
if ((rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_FLAT) ||
(rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_CONSTANT) )
{
// draw as constant shaded
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
// draw the triangle with basic flat rasterizer
Draw_Triangle_2DINVZB_16(&face, video_buffer, lpitch, zbuffer, zpitch);
} // end if
else
if (rend_list->poly_ptrs[poly]->attr & POLY4DV2_ATTR_SHADE_MODE_GOURAUD)
{
// {andre take advantage of the data structures later..}
// set the vertices
face.tvlist[0].x = (float)rend_list->poly_ptrs[poly]->tvlist[0].x;
face.tvlist[0].y = (float)rend_list->poly_ptrs[poly]->tvlist[0].y;
face.tvlist[0].z = (float)rend_list->poly_ptrs[poly]->tvlist[0].z;
face.lit_color[0] = rend_list->poly_ptrs[poly]->lit_color[0];
face.tvlist[1].x = (float)rend_list->poly_ptrs[poly]->tvlist[1].x;
face.tvlist[1].y = (float)rend_list->poly_ptrs[poly]->tvlist[1].y;
face.tvlist[1].z = (float)rend_list->poly_ptrs[poly]->tvlist[1].z;
face.lit_color[1] = rend_list->poly_ptrs[poly]->lit_color[1];
face.tvlist[2].x = (float)rend_list->poly_ptrs[poly]->tvlist[2].x;
face.tvlist[2].y = (float)rend_list->poly_ptrs[poly]->tvlist[2].y;
face.tvlist[2].z = (float)rend_list->poly_ptrs[poly]->tvlist[2].z;
face.lit_color[2] = rend_list->poly_ptrs[poly]->lit_color[2];
// draw the gouraud shaded triangle
Draw_Gouraud_TriangleINVZB_16(&face, video_buffer, lpitch,zbuffer,zpitch);
} // end if gouraud
} // end for poly
} // end Draw_RENDERLIST4DV2_Hybrid_Textured_SolidINVZB_16
///////////////////////////////////////////////////////////////////////////////////////
// 1/Z BUFFERED ALPHA CHANNEL
///////////////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////
void Draw_Triangle_2DINVZB_Alpha16(POLYF4DV2_PTR face, // ptr to face
UCHAR *_dest_buffer, // pointer to video buffer
int mem_pitch, // bytes per line, 320, 640 etc.
UCHAR *_zbuffer, // pointer to z-buffer
int zpitch, // bytes per line of zbuffer
int alpha)
{
// this function draws a flat shaded polygon with zbuffering
int v0=0,
v1=1,
v2=2,
temp=0,
tri_type = TRI_TYPE_NONE,
irestart = INTERP_LHS;
int dx,dy,dyl,dyr, // general deltas
z,
dz,
xi,yi, // the current interpolated x,y
zi, // the current interpolated z
index_x,index_y, // looping vars
x,y, // hold general x,y
xstart,
xend,
ystart,
yrestart,
yend,
xl,
dxdyl,
xr,
dxdyr,
dzdyl,
zl,
dzdyr,
zr;
int x0,y0,tz0, // cached vertices
x1,y1,tz1,
x2,y2,tz2;
USHORT *screen_ptr = NULL,
*screen_line = NULL,
*textmap = NULL,
*dest_buffer = (USHORT *)_dest_buffer;
UINT *z_ptr = NULL,
*zbuffer = (UINT *)_zbuffer;
USHORT color; // polygon color
#ifdef DEBUG_ON
// track rendering stats
debug_polys_rendered_per_frame++;
#endif
// adjust memory pitch to words, divide by 2
mem_pitch >>=1;
// adjust zbuffer pitch for 32 bit alignment
zpitch >>= 2;
// apply fill convention to coordinates
face->tvlist[0].x = (int)(face->tvlist[0].x+0.5);
face->tvlist[0].y = (int)(face->tvlist[0].y+0.5);
face->tvlist[1].x = (int)(face->tvlist[1].x+0.5);
face->tvlist[1].y = (int)(face->tvlist[1].y+0.5);
face->tvlist[2].x = (int)(face->tvlist[2].x+0.5);
face->tvlist[2].y = (int)(face->tvlist[2].y+0.5);
// first trivial clipping rejection tests
if (((face->tvlist[0].y < min_clip_y) &&
(face->tvlist[1].y < min_clip_y) &&
(face->tvlist[2].y < min_clip_y)) ||
((face->tvlist[0].y > max_clip_y) &&
(face->tvlist[1].y > max_clip_y) &&
(face->tvlist[2].y > max_clip_y)) ||
((face->tvlist[0].x < min_clip_x) &&
(face->tvlist[1].x < min_clip_x) &&
(face->tvlist[2].x < min_clip_x)) ||
((face->tvlist[0].x > max_clip_x) &&
(face->tvlist[1].x > max_clip_x) &&
(face->tvlist[2].x > max_clip_x)))
return;
// sort vertices
if (face->tvlist[v1].y < face->tvlist[v0].y)
{SWAP(v0,v1,temp);}
if (face->tvlist[v2].y < face->tvlist[v0].y)
{SWAP(v0,v2,temp);}
if (face->tvlist[v2].y < face->tvlist[v1].y)
{SWAP(v1,v2,temp);}
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v0].y, face->tvlist[v1].y) )
{
// set triangle type
tri_type = TRI_TYPE_FLAT_TOP;
// sort vertices left to right
if (face->tvlist[v1].x < face->tvlist[v0].x)
{SWAP(v0,v1,temp);}
} // end if
else
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v1].y, face->tvlist[v2].y) )
{
// set triangle type
tri_type = TRI_TYPE_FLAT_BOTTOM;
// sort vertices left to right
if (face->tvlist[v2].x < face->tvlist[v1].x)
{SWAP(v1,v2,temp);}
} // end if
else
{
// must be a general triangle
tri_type = TRI_TYPE_GENERAL;
} // end else
// extract vertices for processing, now that we have order
x0 = (int)(face->tvlist[v0].x+0.0);
y0 = (int)(face->tvlist[v0].y+0.0);
tz0 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v0].z+0.5);
x1 = (int)(face->tvlist[v1].x+0.0);
y1 = (int)(face->tvlist[v1].y+0.0);
tz1 = (1 <<FIXP28_SHIFT) / (int)(face->tvlist[v1].z+0.5);
x2 = (int)(face->tvlist[v2].x+0.0);
y2 = (int)(face->tvlist[v2].y+0.0);
tz2 = (1 <<FIXP28_SHIFT) / (int)(face->tvlist[v2].z+0.5);
// degenerate triangle
if ( ((x0 == x1) && (x1 == x2)) || ((y0 == y1) && (y1 == y2)))
return;
// assign both source1 and source2 alpha tables based on polygon alpha level
USHORT *alpha_table_src1 = (USHORT *)&rgb_alpha_table[(NUM_ALPHA_LEVELS-1) - alpha][0];
USHORT *alpha_table_src2 = (USHORT *)&rgb_alpha_table[alpha][0];
// extract constant color
color = face->lit_color[0];
// set interpolation restart value
yrestart = y1;
// what kind of triangle
if (tri_type & TRI_TYPE_FLAT_MASK)
{
if (tri_type == TRI_TYPE_FLAT_TOP)
{
// compute all deltas
dy = (y2 - y0);
dxdyl = ((x2 - x0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz2 - tz0) << 0)/dy;
dxdyr = ((x2 - x1) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz1) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x1 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz1 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x1 << FIXP16_SHIFT);
zl = (tz0 << 0);
zr = (tz1 << 0);
// set starting y
ystart = y0;
} // end else
} // end if flat top
else
{
// must be flat bottom
// compute all deltas
dy = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz1 - tz0) << 0)/dy;
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz0) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
zl = (tz0 << 0);
zr = (tz0 << 0);
// set starting y
ystart = y0;
} // end else
} // end else flat bottom
// test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
dz = (zr - zl)/dx;
} // end if
else
{
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
zi+=dx*dz;
// reset vars
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
// screen_ptr[xi] = color;
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] + alpha_table_src2[color];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,w,z
zi+=dz;
} // end for xi
// interpolate z,x along right and left edge
xl+=dxdyl;
zl+=dzdyl;
xr+=dxdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
} // end for y
} // end if clip
else
{
// non-clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w interpolants
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
dz = (zr - zl)/dx;
} // end if
else
{
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel 5.6.5
// screen_ptr[xi] = color;
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] + alpha_table_src2[color];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate z
zi+=dz;
} // end for xi
// interpolate x,z along right and left edge
xl+=dxdyl;
zl+=dzdyl;
xr+=dxdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
} // end for y
} // end if non-clipped
} // end if
else
if (tri_type==TRI_TYPE_GENERAL)
{
// first test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// pre-test y clipping status
if (y1 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dyr = (min_clip_y - y0);
dyl = (min_clip_y - y1);
// computer new LHS starting values
xl = dxdyl*dyl + (x1 << FIXP16_SHIFT);
zl = dzdyl*dyl + (tz1 << 0);
// compute new RHS starting values
xr = dxdyr*dyr + (x0 << FIXP16_SHIFT);
zr = dzdyr*dyr + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr > dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
if (y0 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
{
// no initial y clipping
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// no clipping y
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
zl = (tz0 << 0);
zr = (tz0 << 0);
// set starting y
ystart = y0;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end else
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for z interpolants
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute z interpolants
if ((dx = (xend - xstart))>0)
{
dz = (zr - zl)/dx;
} // end if
else
{
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
zi+=dx*dz;
// set x to left clip edge
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
// screen_ptr[xi] = color;
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] + alpha_table_src2[color];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate z
zi+=dz;
} // end for xi
// interpolate z,x along right and left edge
xl+=dxdyl;
zl+=dzdyl;
xr+=dxdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end if
else
{
// no x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v,w,z interpolants
zi = zl; // + FIXP16_ROUND_UP;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
dz = (zr - zl)/dx;
} // end if
else
{
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel assume 5.6.5
// screen_ptr[xi] = color;
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] + alpha_table_src2[color];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate z
zi+=dz;
} // end for xi
// interpolate x,z along right and left edge
xl+=dxdyl;
zl+=dzdyl;
xr+=dxdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance z-buffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end else
} // end if
} // end Draw_Triangle_2DINVZB_Alpha16
///////////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_TriangleINVZB_Alpha16(POLYF4DV2_PTR face, // ptr to face
UCHAR *_dest_buffer, // pointer to video buffer
int mem_pitch, // bytes per line, 320, 640 etc.
UCHAR *_zbuffer, // pointer to z-buffer
int zpitch, // bytes per line of zbuffer
int alpha)
{
// this function draws a textured triangle in 16-bit mode
int v0=0,
v1=1,
v2=2,
temp=0,
tri_type = TRI_TYPE_NONE,
irestart = INTERP_LHS;
int dx,dy,dyl,dyr, // general deltas
u,v,z,
du,dv,dz,
xi,yi, // the current interpolated x,y
ui,vi,zi, // the current interpolated u,v,z
index_x,index_y, // looping vars
x,y, // hold general x,y
xstart,
xend,
ystart,
yrestart,
yend,
xl,
dxdyl,
xr,
dxdyr,
dudyl,
ul,
dvdyl,
vl,
dzdyl,
zl,
dudyr,
ur,
dvdyr,
vr,
dzdyr,
zr;
int x0,y0,tu0,tv0,tz0, // cached vertices
x1,y1,tu1,tv1,tz1,
x2,y2,tu2,tv2,tz2;
USHORT *screen_ptr = NULL,
*screen_line = NULL,
*textmap = NULL,
*dest_buffer = (USHORT *)_dest_buffer;
UINT *z_ptr = NULL,
*zbuffer = (UINT *)_zbuffer;
#ifdef DEBUG_ON
// track rendering stats
debug_polys_rendered_per_frame++;
#endif
// extract texture map
textmap = (USHORT *)face->texture->buffer;
// extract base 2 of texture width
int texture_shift2 = logbase2ofx[face->texture->width];
// adjust memory pitch to words, divide by 2
mem_pitch >>=1;
// adjust zbuffer pitch for 32 bit alignment
zpitch >>= 2;
// apply fill convention to coordinates
face->tvlist[0].x = (int)(face->tvlist[0].x+0.5);
face->tvlist[0].y = (int)(face->tvlist[0].y+0.5);
face->tvlist[1].x = (int)(face->tvlist[1].x+0.5);
face->tvlist[1].y = (int)(face->tvlist[1].y+0.5);
face->tvlist[2].x = (int)(face->tvlist[2].x+0.5);
face->tvlist[2].y = (int)(face->tvlist[2].y+0.5);
// first trivial clipping rejection tests
if (((face->tvlist[0].y < min_clip_y) &&
(face->tvlist[1].y < min_clip_y) &&
(face->tvlist[2].y < min_clip_y)) ||
((face->tvlist[0].y > max_clip_y) &&
(face->tvlist[1].y > max_clip_y) &&
(face->tvlist[2].y > max_clip_y)) ||
((face->tvlist[0].x < min_clip_x) &&
(face->tvlist[1].x < min_clip_x) &&
(face->tvlist[2].x < min_clip_x)) ||
((face->tvlist[0].x > max_clip_x) &&
(face->tvlist[1].x > max_clip_x) &&
(face->tvlist[2].x > max_clip_x)))
return;
// sort vertices
if (face->tvlist[v1].y < face->tvlist[v0].y)
{SWAP(v0,v1,temp);}
if (face->tvlist[v2].y < face->tvlist[v0].y)
{SWAP(v0,v2,temp);}
if (face->tvlist[v2].y < face->tvlist[v1].y)
{SWAP(v1,v2,temp);}
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v0].y, face->tvlist[v1].y) )
{
// set triangle type
tri_type = TRI_TYPE_FLAT_TOP;
// sort vertices left to right
if (face->tvlist[v1].x < face->tvlist[v0].x)
{SWAP(v0,v1,temp);}
} // end if
else
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v1].y ,face->tvlist[v2].y))
{
// set triangle type
tri_type = TRI_TYPE_FLAT_BOTTOM;
// sort vertices left to right
if (face->tvlist[v2].x < face->tvlist[v1].x)
{SWAP(v1,v2,temp);}
} // end if
else
{
// must be a general triangle
tri_type = TRI_TYPE_GENERAL;
} // end else
// extract vertices for processing, now that we have order
x0 = (int)(face->tvlist[v0].x+0.0);
y0 = (int)(face->tvlist[v0].y+0.0);
tu0 = (int)(face->tvlist[v0].u0);
tv0 = (int)(face->tvlist[v0].v0);
tz0 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v0].z+0.5);
x1 = (int)(face->tvlist[v1].x+0.0);
y1 = (int)(face->tvlist[v1].y+0.0);
tu1 = (int)(face->tvlist[v1].u0);
tv1 = (int)(face->tvlist[v1].v0);
tz1 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v1].z+0.5);
x2 = (int)(face->tvlist[v2].x+0.0);
y2 = (int)(face->tvlist[v2].y+0.0);
tu2 = (int)(face->tvlist[v2].u0);
tv2 = (int)(face->tvlist[v2].v0);
tz2 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v2].z+0.5);
// degenerate triangle
if ( ((x0 == x1) && (x1 == x2)) || ((y0 == y1) && (y1 == y2)))
return;
// assign both source1 and source2 alpha tables based on polygon alpha level
USHORT *alpha_table_src1 = (USHORT *)&rgb_alpha_table[(NUM_ALPHA_LEVELS-1) - alpha][0];
USHORT *alpha_table_src2 = (USHORT *)&rgb_alpha_table[alpha][0];
// set interpolation restart value
yrestart = y1;
// what kind of triangle
if (tri_type & TRI_TYPE_FLAT_MASK)
{
if (tri_type == TRI_TYPE_FLAT_TOP)
{
// compute all deltas
dy = (y2 - y0);
dxdyl = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu2 - tu0) << FIXP16_SHIFT)/dy;
dvdyl = ((tv2 - tv0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz2 - tz0) << 0)/dy;
dxdyr = ((x2 - x1) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu1) << FIXP16_SHIFT)/dy;
dvdyr = ((tv2 - tv1) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz1) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x1 << FIXP16_SHIFT);
ur = dudyr*dy + (tu1 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv1 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz1 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x1 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu1 << FIXP16_SHIFT);
vr = (tv1 << FIXP16_SHIFT);
zr = (tz1 << 0);
// set starting y
ystart = y0;
} // end else
} // end if flat top
else
{
// must be flat bottom
// compute all deltas
dy = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dy;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dy;
dzdyl = ((tz1 - tz0) << 0)/dy;
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dy;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dy;
dzdyr = ((tz2 - tz0) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu0 << FIXP16_SHIFT);
vr = (tv0 << FIXP16_SHIFT);
zr = (tz0 << 0);
// set starting y
ystart = y0;
} // end else
} // end else flat bottom
// test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ????
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
zi+=dx*dz;
// reset vars
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
//screen_ptr[xi] = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,z
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if clip
else
{
// non-clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ????
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
//screen_ptr[xi] = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,z
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if non-clipped
} // end if
else
if (tri_type==TRI_TYPE_GENERAL)
{
// first test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// pre-test y clipping status
if (y1 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dyr = (min_clip_y - y0);
dyl = (min_clip_y - y1);
// computer new LHS starting values
xl = dxdyl*dyl + (x1 << FIXP16_SHIFT);
ul = dudyl*dyl + (tu1 << FIXP16_SHIFT);
vl = dvdyl*dyl + (tv1 << FIXP16_SHIFT);
zl = dzdyl*dyl + (tz1 << 0);
// compute new RHS starting values
xr = dxdyr*dyr + (x0 << FIXP16_SHIFT);
ur = dudyr*dyr + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dyr + (tv0 << FIXP16_SHIFT);
zr = dzdyr*dyr + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr > dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
if (y0 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << FIXP16_SHIFT);
vl = dvdyl*dy + (tv0 << FIXP16_SHIFT);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << FIXP16_SHIFT);
vr = dvdyr*dy + (tv0 << FIXP16_SHIFT);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end if
else
{
// no initial y clipping
// compute all deltas
// LHS
dyl = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dyl;
dudyl = ((tu1 - tu0) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv1 - tv0) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz1 - tz0) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv2 - tv0) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// no clipping y
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << FIXP16_SHIFT);
vl = (tv0 << FIXP16_SHIFT);
zl = (tz0 << 0);
ur = (tu0 << FIXP16_SHIFT);
vr = (tv0 << FIXP16_SHIFT);
zr = (tz0 << 0);
// set starting y
ystart = y0;
// test if we need swap to keep rendering left to right
if (dxdyr < dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);
SWAP(tz1,tz2,temp);
// set interpolation restart
irestart = INTERP_RHS;
} // end if
} // end else
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ???
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
zi+=dx*dz;
// set x to left clip edge
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
//screen_ptr[xi] = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,z
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end if
else
{
// no x clipping
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
ui = ul + FIXP16_ROUND_UP;
vi = vl + FIXP16_ROUND_UP;
zi = zl;// + FIXP16_ROUND_UP; // ????
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul)/dx;
dv = (vr - vl)/dx;
dz = (zr - zl)/dx;
} // end if
else
{
du = (ur - ul);
dv = (vr - vl);
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
//screen_ptr[xi] = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
// test for yi hitting second region, if so change interpolant
if (yi==yrestart)
{
// test interpolation side change flag
if (irestart == INTERP_LHS)
{
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << FIXP16_SHIFT)/dyl;
dvdyl = ((tv2 - tv1) << FIXP16_SHIFT)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << FIXP16_SHIFT);
vl = (tv1 << FIXP16_SHIFT);
zl = (tz1 << 0);
// interpolate down on LHS to even up
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
} // end if
else
{
// RHS
dyr = (y1 - y2);
dxdyr = ((x1 - x2) << FIXP16_SHIFT)/dyr;
dudyr = ((tu1 - tu2) << FIXP16_SHIFT)/dyr;
dvdyr = ((tv1 - tv2) << FIXP16_SHIFT)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << FIXP16_SHIFT);
vr = (tv2 << FIXP16_SHIFT);
zr = (tz2 << 0);
// interpolate down on RHS to even up
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
} // end else
} // end if
} // end for y
} // end else
} // end if
} // end Draw_Textured_Triangle_INVZB_Alpha16
////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_Perspective_Triangle_INVZB_Alpha16(POLYF4DV2_PTR face, // ptr to face
UCHAR *_dest_buffer, // pointer to video buffer
int mem_pitch, // bytes per line, 320, 640 etc.
UCHAR *_zbuffer, // pointer to z-buffer
int zpitch, // bytes per line of zbuffer
int alpha)
{
// this function draws a textured triangle in 16-bit mode using a 1/z buffer and piecewise linear
// perspective correct texture mappping, 1/z, u/z, v/z are interpolated down each edge then to draw
// each span U and V are computed for each end point and the space is broken up into 32 pixel
// spans where the correct U,V is computed at each point along the span, but linearly interpolated
// across the span
int v0=0,
v1=1,
v2=2,
temp=0,
tri_type = TRI_TYPE_NONE,
irestart = INTERP_LHS;
int dx,dy,dyl,dyr, // general deltas
u,v,z,
du,dv,dz,
xi,yi, // the current interpolated x,y
ui,vi,zi, // the current interpolated u,v,z
index_x,index_y, // looping vars
x,y, // hold general x,y
xstart,
xend,
ystart,
yrestart,
yend,
xl,
dxdyl,
xr,
dxdyr,
dudyl,
ul,
dvdyl,
vl,
dzdyl,
zl,
dudyr,
ur,
dvdyr,
vr,
dzdyr,
zr;
int x0,y0,tu0,tv0,tz0, // cached vertices
x1,y1,tu1,tv1,tz1,
x2,y2,tu2,tv2,tz2;
USHORT *screen_ptr = NULL,
*screen_line = NULL,
*textmap = NULL,
*dest_buffer = (USHORT *)_dest_buffer;
UINT *z_ptr = NULL,
*zbuffer = (UINT *)_zbuffer;
#ifdef DEBUG_ON
// track rendering stats
debug_polys_rendered_per_frame++;
#endif
// extract texture map
textmap = (USHORT *)face->texture->buffer;
// extract base 2 of texture width
int texture_shift2 = logbase2ofx[face->texture->width];
// adjust memory pitch to words, divide by 2
mem_pitch >>=1;
// adjust zbuffer pitch for 32 bit alignment
zpitch >>= 2;
// apply fill convention to coordinates
face->tvlist[0].x = (int)(face->tvlist[0].x+0.5);
face->tvlist[0].y = (int)(face->tvlist[0].y+0.5);
face->tvlist[1].x = (int)(face->tvlist[1].x+0.5);
face->tvlist[1].y = (int)(face->tvlist[1].y+0.5);
face->tvlist[2].x = (int)(face->tvlist[2].x+0.5);
face->tvlist[2].y = (int)(face->tvlist[2].y+0.5);
// first trivial clipping rejection tests
if (((face->tvlist[0].y < min_clip_y) &&
(face->tvlist[1].y < min_clip_y) &&
(face->tvlist[2].y < min_clip_y)) ||
((face->tvlist[0].y > max_clip_y) &&
(face->tvlist[1].y > max_clip_y) &&
(face->tvlist[2].y > max_clip_y)) ||
((face->tvlist[0].x < min_clip_x) &&
(face->tvlist[1].x < min_clip_x) &&
(face->tvlist[2].x < min_clip_x)) ||
((face->tvlist[0].x > max_clip_x) &&
(face->tvlist[1].x > max_clip_x) &&
(face->tvlist[2].x > max_clip_x)))
return;
// sort vertices
if (face->tvlist[v1].y < face->tvlist[v0].y)
{SWAP(v0,v1,temp);}
if (face->tvlist[v2].y < face->tvlist[v0].y)
{SWAP(v0,v2,temp);}
if (face->tvlist[v2].y < face->tvlist[v1].y)
{SWAP(v1,v2,temp);}
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v0].y, face->tvlist[v1].y) )
{
// set triangle type
tri_type = TRI_TYPE_FLAT_TOP;
// sort vertices left to right
if (face->tvlist[v1].x < face->tvlist[v0].x)
{SWAP(v0,v1,temp);}
} // end if
else
// now test for trivial flat sided cases
if (FCMP(face->tvlist[v1].y ,face->tvlist[v2].y))
{
// set triangle type
tri_type = TRI_TYPE_FLAT_BOTTOM;
// sort vertices left to right
if (face->tvlist[v2].x < face->tvlist[v1].x)
{SWAP(v1,v2,temp);}
} // end if
else
{
// must be a general triangle
tri_type = TRI_TYPE_GENERAL;
} // end else
// extract vertices for processing, now that we have order
x0 = (int)(face->tvlist[v0].x+0.0);
y0 = (int)(face->tvlist[v0].y+0.0);
tu0 = ((int)(face->tvlist[v0].u0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v0].z+0.5);
tv0 = ((int)(face->tvlist[v0].v0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v0].z+0.5);
tz0 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v0].z+0.5);
x1 = (int)(face->tvlist[v1].x+0.0);
y1 = (int)(face->tvlist[v1].y+0.0);
tu1 = ((int)(face->tvlist[v1].u0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v1].z+0.5);
tv1 = ((int)(face->tvlist[v1].v0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v1].z+0.5);
tz1 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v1].z+0.5);
x2 = (int)(face->tvlist[v2].x+0.0);
y2 = (int)(face->tvlist[v2].y+0.0);
tu2 = ((int)(face->tvlist[v2].u0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v2].z+0.5);
tv2 = ((int)(face->tvlist[v2].v0+0.5) << FIXP22_SHIFT) / (int)(face->tvlist[v2].z+0.5);
tz2 = (1 << FIXP28_SHIFT) / (int)(face->tvlist[v2].z+0.5);
// degenerate triangle
if ( ((x0 == x1) && (x1 == x2)) || ((y0 == y1) && (y1 == y2)))
return;
// assign both source1 and source2 alpha tables based on polygon alpha level
USHORT *alpha_table_src1 = (USHORT *)&rgb_alpha_table[(NUM_ALPHA_LEVELS-1) - alpha][0];
USHORT *alpha_table_src2 = (USHORT *)&rgb_alpha_table[alpha][0];
// set interpolation restart value
yrestart = y1;
// what kind of triangle
if (tri_type & TRI_TYPE_FLAT_MASK)
{
if (tri_type == TRI_TYPE_FLAT_TOP)
{
// compute all deltas
dy = (y2 - y0);
dxdyl = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu2 - tu0) << 0)/dy;
dvdyl = ((tv2 - tv0) << 0)/dy;
dzdyl = ((tz2 - tz0) << 0)/dy;
dxdyr = ((x2 - x1) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu1) << 0)/dy;
dvdyr = ((tv2 - tv1) << 0)/dy;
dzdyr = ((tz2 - tz1) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << 0);
vl = dvdyl*dy + (tv0 << 0);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x1 << FIXP16_SHIFT);
ur = dudyr*dy + (tu1 << 0);
vr = dvdyr*dy + (tv1 << 0);
zr = dzdyr*dy + (tz1 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x1 << FIXP16_SHIFT);
ul = (tu0 << 0);
vl = (tv0 << 0);
zl = (tz0 << 0);
ur = (tu1 << 0);
vr = (tv1 << 0);
zr = (tz1 << 0);
// set starting y
ystart = y0;
} // end else
} // end if flat top
else
{
// must be flat bottom
// compute all deltas
dy = (y1 - y0);
dxdyl = ((x1 - x0) << FIXP16_SHIFT)/dy;
dudyl = ((tu1 - tu0) << 0)/dy;
dvdyl = ((tv1 - tv0) << 0)/dy;
dzdyl = ((tz1 - tz0) << 0)/dy;
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dy;
dudyr = ((tu2 - tu0) << 0)/dy;
dvdyr = ((tv2 - tv0) << 0)/dy;
dzdyr = ((tz2 - tz0) << 0)/dy;
// test for y clipping
if (y0 < min_clip_y)
{
// compute overclip
dy = (min_clip_y - y0);
// computer new LHS starting values
xl = dxdyl*dy + (x0 << FIXP16_SHIFT);
ul = dudyl*dy + (tu0 << 0);
vl = dvdyl*dy + (tv0 << 0);
zl = dzdyl*dy + (tz0 << 0);
// compute new RHS starting values
xr = dxdyr*dy + (x0 << FIXP16_SHIFT);
ur = dudyr*dy + (tu0 << 0);
vr = dvdyr*dy + (tv0 << 0);
zr = dzdyr*dy + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
} // end if
else
{
// no clipping
// set starting values
xl = (x0 << FIXP16_SHIFT);
xr = (x0 << FIXP16_SHIFT);
ul = (tu0 << 0);
vl = (tv0 << 0);
zl = (tz0 << 0);
ur = (tu0 << 0);
vr = (tv0 << 0);
zr = (tz0 << 0);
// set starting y
ystart = y0;
} // end else
} // end else flat bottom
// test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// test for horizontal clipping
if ((x0 < min_clip_x) || (x0 > max_clip_x) ||
(x1 < min_clip_x) || (x1 > max_clip_x) ||
(x2 < min_clip_x) || (x2 > max_clip_x))
{
// clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul + 0;
vi = vl + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul) / dx;
dv = (vr - vl) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur - ul) ;
dv = (vr - vl) ;
dz = (zr - zl);
} // end else
///////////////////////////////////////////////////////////////////////
// test for x clipping, LHS
if (xstart < min_clip_x)
{
// compute x overlap
dx = min_clip_x - xstart;
// slide interpolants over
ui+=dx*du;
vi+=dx*dv;
zi+=dx*dz;
// reset vars
xstart = min_clip_x;
} // end if
// test for x clipping RHS
if (xend > max_clip_x)
xend = max_clip_x;
///////////////////////////////////////////////////////////////////////
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) +
(((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,z
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if clip
else
{
// non-clip version
// point screen ptr to starting line
screen_ptr = dest_buffer + (ystart * mem_pitch);
// point zbuffer to starting line
z_ptr = zbuffer + (ystart * zpitch);
for (yi = ystart; yi < yend; yi++)
{
// compute span endpoints
xstart = ((xl + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
xend = ((xr + FIXP16_ROUND_UP) >> FIXP16_SHIFT);
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul + 0;
vi = vl + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur - ul) / dx;
dv = (vr - vl) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur - ul) ;
dv = (vr - vl) ;
dz = (zr - zl);
} // end else
// draw span
for (xi=xstart; xi < xend; xi++)
{
// test if z of current pixel is nearer than current z buffer value
if (zi > z_ptr[xi])
{
// write textel
screen_ptr[xi] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) +
(((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)]];
// update z-buffer
z_ptr[xi] = zi;
} // end if
// interpolate u,v,z
ui+=du;
vi+=dv;
zi+=dz;
} // end for xi
// interpolate u,v,x along right and left edge
xl+=dxdyl;
ul+=dudyl;
vl+=dvdyl;
zl+=dzdyl;
xr+=dxdyr;
ur+=dudyr;
vr+=dvdyr;
zr+=dzdyr;
// advance screen ptr
screen_ptr+=mem_pitch;
// advance zbuffer ptr
z_ptr+=zpitch;
} // end for y
} // end if non-clipped
} // end if
else
if (tri_type==TRI_TYPE_GENERAL)
{
// first test for bottom clip, always
if ((yend = y2) > max_clip_y)
yend = max_clip_y;
// pre-test y clipping status
if (y1 < min_clip_y)
{
// compute all deltas
// LHS
dyl = (y2 - y1);
dxdyl = ((x2 - x1) << FIXP16_SHIFT)/dyl;
dudyl = ((tu2 - tu1) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// RHS
dyr = (y2 - y0);
dxdyr = ((x2 - x0) << FIXP16_SHIFT)/dyr;
dudyr = ((tu2 - tu0) << 0)/dyr;
dvdyr = ((tv2 - tv0) << 0)/dyr;
dzdyr = ((tz2 - tz0) << 0)/dyr;
// compute overclip
dyr = (min_clip_y - y0);
dyl = (min_clip_y - y1);
// computer new LHS starting values
xl = dxdyl*dyl + (x1 << FIXP16_SHIFT);
ul = dudyl*dyl + (tu1 << 0);
vl = dvdyl*dyl + (tv1 << 0);
zl = dzdyl*dyl + (tz1 << 0);
// compute new RHS starting values
xr = dxdyr*dyr + (x0 << FIXP16_SHIFT);
ur = dudyr*dyr + (tu0 << 0);
vr = dvdyr*dyr + (tv0 << 0);
zr = dzdyr*dyr + (tz0 << 0);
// compute new starting y
ystart = min_clip_y;
// test if we need swap to keep rendering left to right
if (dxdyr > dxdyl)
{
SWAP(dxdyl,dxdyr,temp);
SWAP(dudyl,dudyr,temp);
SWAP(dvdyl,dvdyr,temp);
SWAP(dzdyl,dzdyr,temp);
SWAP(xl,xr,temp);
SWAP(ul,ur,temp);
SWAP(vl,vr,temp);
SWAP(zl,zr,temp);
SWAP(x1,x2,temp);
SWAP(y1,y2,temp);
SWAP(tu1,tu2,temp);
SWAP(tv1,tv2,temp);