openGL—中点Bresenham椭圆算法

朴灿烈づ我的快乐病毒、 2022-06-17 13:53 183阅读 0赞

// bb.cpp : 定义控制台应用程序的入口点。
    #include "stdafx.h"
    #include <gl/glut.h> 
    
    void init(void)    
    {
         glClearColor(0.0,0.0,0.0,0.0);    //设置背景颜色为黑色    
         glMatrixMode(GL_PROJECTION);       //对投影相关进行操作 
         gluOrtho2D(0.0, 30.0, 0.0, 30.0);
     }
    
     void putpixel(int x, int y)
    {
        glColor3f(1.0, 0.0, 0.0);      
        glPointSize(2.0f);
        glBegin(GL_POINTS);
            glVertex2f(15+x, 15+y);
        glEnd();
        glFlush();
    }
     void MidBresenhamEllipse(int a,int b)
     {
         int x,y;
    	 float d1,d2;
         x=0;
    	 y=b;
    	 d1=b*b+a*a*(-b+0.25);
    	 putpixel(x,y);
    	 putpixel(-x,-y);
    	 putpixel(-x,y);
    	 putpixel(x,-y);
         while(b*b*(x+1)<a*a*(y-0.5))
    	 {
             if(d1<=0)
    		 {
                 d1+=b*b*(2*x+3);
    			 x++;
    		 }
             else
    		 {
                 d1+=b*b*(2*x+3)+a*a*(-2*y+2);
    			 x++;
                 y--;
             }
    		putpixel(x,y);
    		putpixel(-x,-y);
    		putpixel(-x,y);
    		putpixel(x,-y);
         }/*while上半部分*/
    	 d2=b*b*(x+0.5)*(x+0.5)+a*a*(y-1)*(y-1)-a*a*b*b;
    	 while(y>0)
    	 {
    		 if(d2<=0)
    		 {
    			 d2+=b*b*(2*x+2)+a*a*(-2*y+3);
    			 x++;
    			 y--;
    		 }
    		 else
    		 {
    			 d2+=a*a*(-2*y+3);
    			 y--;
    		 }
    		putpixel(x,y);
    		putpixel(-x,-y);
    		putpixel(-x,y);
    		putpixel(x,-y);
    	 }
     }
    
     void display()
     {
         glClear(GL_COLOR_BUFFER_BIT);       
         MidBresenhamEllipse(6,5);    //长半轴a=6, 短半轴b=5
     }
     
     int main(int argc,char** argv)
     {
    
         glutInit(&argc,argv);
         glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);  
         glutInitWindowSize(400,400);   
         glutInitWindowPosition(0,0);    
         glutCreateWindow("中点Bresenham画椭圆");   
         glutDisplayFunc(display);    
         init();       
         glutMainLoop();   
     
         return 0;
     }

运行结果：

![Center][]

[Center]: /images/20220617/3d23096b64b3412d8647bcb89be62ebf.png