游戏引擎

开发平台：
Visual C++

FrustumCull.cpp：源码内容
							// FrustumCull.cpp: implementation of the CFrustumCull class.
//
//////////////////////////////////////////////////////////////////////
#include "stdafx.h"
#include "FrustumCull.h"
#include <math.h>
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
CFrustumCull::CFrustumCull()
{  
	m_HalfFOV=40;
	m_ViewerRotate=0;
	m_ViewDistance=30;
    m_ViewerX=m_ViewerZ=0;
	m_ViewLeftX=m_ViewLeftZ=0;
	m_ViewRightX=m_ViewRightZ=0;
    m_FarFoucsX=m_FarFoucsZ=0;
	m_BackLeftX=m_BackLeftZ=0;
	m_BackRightX=m_BackRightZ=0;
    m_MaxX=m_MaxZ=0;
	m_MinX=m_MinZ=256;
	
	for(int i=0;i<128;i++)
	{
		m_LeftArray[i]=0;
		m_RightArray[i]=0;
	}
}
void CFrustumCull::InitFrustumCull(int halfFOV,int distance)
{
	m_HalfFOV=halfFOV;
	m_ViewDistance=distance;
	if(m_ViewDistance>125)m_ViewDistance=125;
}
CFrustumCull::~CFrustumCull()
{
}
void CFrustumCull::UpdateFrustumCull(float angle)
{
	/////////////update viewer rotate //////
    m_ViewerRotate=angle;
    /////////////////////////////////////////////
    ///////////// Calculate Frustum /////////////
    /////////////////////////////////////////////
	///////////////get view back,left and right
    m_BackLeftX =-int(4*sinf((m_ViewerRotate+150)*0.01745329f));
    m_BackLeftZ =-int(4*cosf((m_ViewerRotate+150)*0.01745329f));
    m_BackRightX=-int(4*sinf((m_ViewerRotate-150)*0.01745329f));
    m_BackRightZ=-int(4*cosf((m_ViewerRotate-150)*0.01745329f));
    m_FarFoucsX =-int(m_ViewDistance*sinf(m_ViewerRotate*0.01745329f));
	m_FarFoucsZ =-int(m_ViewDistance*cosf(m_ViewerRotate*0.01745329f));
    m_ViewLeftX =-int(m_ViewDistance*sinf((m_ViewerRotate+m_HalfFOV)*0.01745329f));
    m_ViewLeftZ =-int(m_ViewDistance*cosf((m_ViewerRotate+m_HalfFOV)*0.01745329f));
    m_ViewRightX=-int(m_ViewDistance*sinf((m_ViewerRotate-m_HalfFOV)*0.01745329f));
    m_ViewRightZ=-int(m_ViewDistance*cosf((m_ViewerRotate-m_HalfFOV)*0.01745329f));
	////////////////get Rectangle boundary
    m_MaxX=m_MaxZ=0;
	m_MinX=m_MinZ=256;
    if(m_ViewLeftX>m_MaxX)m_MaxX=m_ViewLeftX;
    if(m_ViewLeftZ>m_MaxZ)m_MaxZ=m_ViewLeftZ;
    if(m_ViewRightX>m_MaxX)m_MaxX=m_ViewRightX;
    if(m_ViewRightZ>m_MaxZ)m_MaxZ=m_ViewRightZ;
    if(m_FarFoucsX>m_MaxX)m_MaxX=m_FarFoucsX;
    if(m_FarFoucsZ>m_MaxZ)m_MaxZ=m_FarFoucsZ;
    if(m_BackLeftX>m_MaxX)m_MaxX=m_BackLeftX;
    if(m_BackLeftZ>m_MaxZ)m_MaxZ=m_BackLeftZ;
    if(m_BackRightX>m_MaxX)m_MaxX=m_BackRightX;
    if(m_BackRightZ>m_MaxZ)m_MaxZ=m_BackRightZ;
    if(m_ViewLeftX<m_MinX)m_MinX=m_ViewLeftX;
    if(m_ViewLeftZ<m_MinZ)m_MinZ=m_ViewLeftZ;
    if(m_ViewRightX<m_MinX)m_MinX=m_ViewRightX;
    if(m_ViewRightZ<m_MinZ)m_MinZ=m_ViewRightZ;
    if(m_FarFoucsX<m_MinX)m_MinX=m_FarFoucsX;
    if(m_FarFoucsZ<m_MinZ)m_MinZ=m_FarFoucsZ;
    if(m_BackLeftX<m_MinX)m_MinX=m_BackLeftX;
    if(m_BackLeftZ<m_MinZ)m_MinZ=m_BackLeftZ;
    if(m_BackRightX<m_MinX)m_MinX=m_BackRightX;
    if(m_BackRightZ<m_MinZ)m_MinZ=m_BackRightZ;
	/////////////////Fill array//////////////////////////////
    BresenhamFill(m_ViewLeftX,m_ViewLeftZ,m_FarFoucsX,m_FarFoucsZ,
		          m_LeftArray);
    BresenhamFill(m_FarFoucsX,m_FarFoucsZ,m_ViewRightX,m_ViewRightZ,
		          m_RightArray);
	///////////// GOOD WORK !!!!
	///////////// Now ,we get two boundary array
}
void CFrustumCull::BresenhamFill(int startx,int startz,int endx,int endz, char *pArray)
{
    ///////////// Bresenham Line
	int    dx=1;
	int    dz=1;
	int    x, z;
	int    d;
	int    SignX,SignZ;
	bool   bChange;
	if(endx>startx)
	{
		dx=endx-startx;
		SignX=1;
	}
	else
	{
		dx=startx-endx;
		SignX=-1;
	}
	if(endz>startz)
	{
		dz=endz-startz;
		SignZ=1;
	}
	else
	{
		dz=startz-endz;	
		SignZ=-1;
	}
    x=startx;
	z=startz;
	if(dz>dx)
	{
		int temp;
 		temp=dx; dx=dz;dz=temp;
		bChange=true;
        pArray[124]=dx+1;      //存储个数
        pArray[125]=startz;  //起始
        pArray[126]=endz;    //结束
        pArray[127]=1;       //Z轴加
	}
	else
	{
		bChange=false;
        pArray[124]=dx+1;      //存储个数
        pArray[125]=startx;  //起始
        pArray[126]=endx;    //结束
        pArray[127]=0;       //X轴加
	}
	d=2*dz-dx;
	////////////////////////
	for(int i=0;i<dx+1;i++)
	{
	    if(bChange)
            pArray[i]=x;
        else
            pArray[i]=z;
		if(d>=0)
		{
			if(bChange) x+=SignX;
			else z+=SignZ;
			d=d-dx*2;
		}
        if(bChange)z+=SignZ;
		else x+=SignX;
		d=d+dz*2;
	}
}

						