opengl实现直线扫描算法和区域填充算法

void k1() //0<k<1 
{ 
 glClear(GL_COLOR_BUFFER_BIT); 
 
 glColor3f(0.0,0.0,0.0); 
 glBegin(GL_POINTS); 
 GLint x1=0,y1=0,x2=400,y2=200; 
 GLint x=x1,y=y1; 
 GLint dx=x2-x1,dy=y2-y1,dT=2*(dy-dx),dS=2*dy; 
 GLint d=2*dy-dx; 
 glVertex2i(x,y); 
 while(x<x2) 
 { 
 x++; 
 if(d<0) 
 d=d+dS; 
 else 
 { 
 y++; 
 d=d+dT; 
 } 
 glVertex2i(x,y); 
 } 
 glEnd(); 
 glFlush(); 
 
}

区域填充
#include "gl/glut.h"
#include "windows.h"
const int POINTNUM=7; //多边形点数.
 
/******定义结构体用于活性边表AET和新边表NET***********************************/
 typedef struct XET
 {
 float x;
 float dx,ymax;
 XET* next;
 }AET,NET;
 
/******定义点结构体point******************************************************/
 struct point
 {
 float x;
 float y;
 }
 polypoint[POINTNUM]={250,50,550,150,550,400,250,250,100,350,100,100,120,30};//多边形顶点
 
 void PolyScan()
{
/******计算最高点的y坐标(扫描到此结束)****************************************/
 int MaxY=0;
 int i;
 for(i=0;i<POINTNUM;i++)
 if(polypoint[i].y>MaxY)
 MaxY=polypoint[i].y;
 
/*******初始化AET表***********************************************************/
 AET *pAET=new AET;
 pAET->next=NULL;
 
/******初始化NET表************************************************************/
 NET *pNET[1024];
 for(i=0;i<=MaxY;i++)
 {
 pNET[i]=new NET;
 pNET[i]->next=NULL;
 }
 glClear(GL_COLOR_BUFFER_BIT); //赋值的窗口显示. 
 glColor3f(0.0,0.0,0.0);  //设置直线的颜色红色
 glBegin(GL_POINTS);
/******扫描并建立NET表*********************************************************/
 for(i=0;i<=MaxY;i++)
 {
 for(int j=0;j<POINTNUM;j++)
 if(polypoint[j].y==i)
 { //一个点跟前面的一个点形成一条线段，跟后面的点也形成线段 
 if(polypoint[(j-1+POINTNUM)%POINTNUM].y>polypoint[j].y)
 {
 NET *p=new NET;
 p->x=polypoint[j].x;
 p->ymax=polypoint[(j-1+POINTNUM)%POINTNUM].y;
 p->dx=(polypoint[(j-1+POINTNUM)%POINTNUM].x-polypoint[j].x)/(polypoint[(j-1+POINTNUM)%POINTNUM].y-polypoint[j].y);
 p->next=pNET[i]->next;
 pNET[i]->next=p;
 
 }
 if(polypoint[(j+1+POINTNUM)%POINTNUM].y>polypoint[j].y)
 {
 NET *p=new NET; 
 p->x=polypoint[j].x;
 p->ymax=polypoint[(j+1+POINTNUM)%POINTNUM].y;
 p->dx=(polypoint[(j+1+POINTNUM)%POINTNUM].x-polypoint[j].x)/(polypoint[(j+1+POINTNUM)%POINTNUM].y-polypoint[j].y);
 p->next=pNET[i]->next;
 pNET[i]->next=p;
 }
 }
 }
/******建立并更新活性边表AET*****************************************************/
for(i=0;i<=MaxY;i++)
 {
 //计算新的交点x,更新AET
 NET *p=pAET->next;
 while(p)
 {
 p->x=p->x + p->dx;
 p=p->next;
 }
 //更新后新AET先排序*************************************************************/
 //断表排序,不再开辟空间
 AET *tq=pAET;
 p=pAET->next;
 tq->next=NULL;
 while(p)
 {
 while(tq->next && p->x >= tq->next->x)
 tq=tq->next;
 NET *s=p->next;
 p->next=tq->next;
 tq->next=p;
 p=s;
 tq=pAET;
 }
 //(改进算法)先从AET表中删除ymax==i的结点****************************************/
 AET *q=pAET;
 p=q->next;
 while(p)
 {
 if(p->ymax==i)
 {
 q->next=p->next;
 delete p;
 p=q->next;
 }
 else
 {
 q=q->next;
 p=q->next;
 }
 }
 //将NET中的新点加入AET,并用插入法按X值递增排序**********************************/
 p=pNET[i]->next;
 q=pAET;
 while(p)
 {
 while(q->next && p->x >= q->next->x)
 q=q->next;
 NET *s=p->next;
 p->next=q->next;
 q->next=p;
 p=s;
 q=pAET;
 }
/******配对填充颜色***************************************************************/
 
  p=pAET->next;
 while(p && p->next)
 {
 for(float j=p->x;j<=p->next->x;j++)
 glVertex2i(static_cast<int>(j),i);
 p=p->next->next;//考虑端点情况
 }
 
 
 }
 glEnd();
glFlush(); 
}
void init(void)
{glClearColor(1.0,1.0,1.0,0.0);
//窗口的背景颜色设置为白色
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0.0,600.0,0.0,450.0);
}
 
void main(int argc,char* argv)
{
 glutInit(&argc,&argv);  //I初始化 GLUT.
 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //设置显示模式：单个缓存和使用RGB模型
 glutInitWindowPosition(50,100); //设置窗口的顶部和左边位置
 glutInitWindowSize(400,300); //设置窗口的高度和宽度
 glutCreateWindow("An Example OpenGL Program"); //创建显示窗口
 
 init();    //调用初始化过程
 glutDisplayFunc(PolyScan); //图形的定义传递给我window.
 glutMainLoop();   //显示所有的图形并等待
 }