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t3dlib10.cpp：源码内容

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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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
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;
// 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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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;
// no clipping y
// 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;
// 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
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;
// 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] = 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;
// 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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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
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
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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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_Perspective_Triangle_INVZB_Alpha16
//////////////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_PerspectiveLP_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 ur2, ul2, vr2, vl2;
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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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 >> FIXP22_SHIFT) +
((vi >> FIXP22_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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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 >> FIXP22_SHIFT) +
((vi >> FIXP22_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) << 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);
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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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
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;
// 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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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;
// no clipping y
// 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;
// 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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[textmap[ (ui >> FIXP22_SHIFT) +
((vi >> FIXP22_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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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 >> FIXP22_SHIFT) +
((vi >> FIXP22_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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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_PerspectiveLP_Triangle_INVZB_Alpha16
//////////////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_Perspective_Triangle_FSINVZB_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;
USHORT r_base, g_base, b_base,
r_textel, g_textel, b_textel, textel;
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 base color of lit poly, so we can modulate texture a bit
// for lighting
_RGB565FROM16BIT(face->lit_color[0], &r_base, &g_base, &b_base);
// 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
// get textel first
textel = textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) + ( ((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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
// get textel first
textel = textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) + ( ((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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);
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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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
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;
// 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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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;
// no clipping y
// 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;
// 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
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;
// 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
// get textel first
textel = textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) + ( ((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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
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
// get textel first
textel = textmap[ ((ui << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) + ( ((vi << (FIXP28_SHIFT - FIXP22_SHIFT)) / zi) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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_Perspective_Triangle_FSINVZB_Alpha16
//////////////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_PerspectiveLP_Triangle_FSINVZB_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;
int ur2, ul2, vr2, vl2;
USHORT *screen_ptr = NULL,
*screen_line = NULL,
*textmap = NULL,
*dest_buffer = (USHORT *)_dest_buffer;
USHORT r_base, g_base, b_base,
r_textel, g_textel, b_textel, textel;
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 base color of lit poly, so we can modulate texture a bit
// for lighting
_RGB565FROM16BIT(face->lit_color[0], &r_base, &g_base, &b_base);
// 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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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
// get textel first
textel = textmap[ (ui >> FIXP22_SHIFT) + ((vi >> FIXP22_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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
// get textel first
textel = textmap[ (ui >> FIXP22_SHIFT) + ((vi >> FIXP22_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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);
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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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
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;
// 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) << 0)/dyl;
dvdyl = ((tv1 - tv0) << 0)/dyl;
dzdyl = ((tz1 - tz0) << 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;
// no clipping y
// 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;
// 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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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
// get textel first
textel = textmap[ (ui >> FIXP22_SHIFT) + ((vi >> FIXP22_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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);
ul2 = ((ul << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
ur2 = ((ur << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
vl2 = ((vl << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zl >> 6) ) << 16;
vr2 = ((vr << (FIXP28_SHIFT - FIXP22_SHIFT)) / (zr >> 6) ) << 16;
// compute starting points for u,v interpolants
zi = zl + 0; // ????
ui = ul2 + 0;
vi = vl2 + 0;
// compute u,v interpolants
if ((dx = (xend - xstart))>0)
{
du = (ur2 - ul2) / dx;
dv = (vr2 - vl2) / dx;
dz = (zr - zl) / dx;
} // end if
else
{
du = (ur2 - ul2) ;
dv = (vr2 - vl2) ;
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
// get textel first
textel = textmap[ (ui >> FIXP22_SHIFT) + ((vi >> FIXP22_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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) << 0)/dyl;
dvdyl = ((tv2 - tv1) << 0)/dyl;
dzdyl = ((tz2 - tz1) << 0)/dyl;
// set starting values
xl = (x1 << FIXP16_SHIFT);
ul = (tu1 << 0);
vl = (tv1 << 0);
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) << 0)/dyr;
dvdyr = ((tv1 - tv2) << 0)/dyr;
dzdyr = ((tz1 - tz2) << 0)/dyr;
// set starting values
xr = (x2 << FIXP16_SHIFT);
ur = (tu2 << 0);
vr = (tv2 << 0);
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_PerspectiveLP_Triangle_FSINVZB_Alpha16
///////////////////////////////////////////////////////////////////////////////
void Draw_Textured_TriangleFSINVZB_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 with flat shading
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,
dzdyl,
zl,
dvdyl,
vl,
dudyr,
ur,
dvdyr,
vr,
dzdyr,
zr;
USHORT r_base, g_base, b_base,
r_textel, g_textel, b_textel, textel;
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 base color of lit poly, so we can modulate texture a bit
// for lighting
_RGB565FROM16BIT(face->lit_color[0], &r_base, &g_base, &b_base);
// 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
// get textel first
textel = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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
// get textel first
textel = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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
// get textel first
textel = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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 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,z 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
// get textel first
textel = textmap[(ui >> FIXP16_SHIFT) + ((vi >> FIXP16_SHIFT) << texture_shift2)];
// extract rgb components
r_textel = ((textel >> 11) );
g_textel = ((textel >> 5) & 0x3f);
b_textel = (textel & 0x1f);
// modulate textel with lit background color
r_textel*=r_base;
g_textel*=g_base;
b_textel*=b_base;
// 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] = alpha_table_src1[screen_ptr[xi]] +
alpha_table_src2[((b_textel >> 5) + ((g_textel >> 6) << 5) + ((r_textel >> 5) << 11))];
// 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 else
} // end if
} // end Draw_Textured_TriangleFSINVZB_Alpha16
////////////////////////////////////////////////////////////////////////////////
void Draw_Textured_TriangleGSINVZB_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 gouraud shaded polygon, and z bufferedbased on the affine texture mapper,
// we simply interpolate the (R,G,B) values across the polygons along with the texture coordinates
// and then modulate to get the final color
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, s,t,
du,dv,dw,dz, ds, dt,
xi,yi, // the current interpolated x,y
ui,vi,wi,zi, si, ti, // the current interpolated u,v
index_x,index_y, // looping vars
x,y, // hold general x,y
xstart,
xend,
ystart,