OPENGL—DDA画直线

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// DDA画直线
#include "stdafx.h"
#include <gl/glut.h>
#include <cmath>

void init(void)    
{
     glClearColor(1.0,1.0,1.0,1.0);    //设置背景颜色为白色    
     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 DDALine(int x0,int y0,int x1,int y1)
{
	int dx,dy,epsl,k;
	float x,y,xIncre,yIncre;
	dx=x1-x0;
	dy=y1-y0;
	x=x0;
	y=y0;
	if(abs(dx)>abs(dy))
		epsl=abs(dx);
	else
		epsl=abs(dy);
	xIncre=(float)dx/(float)epsl;
	yIncre=(float)dy/(float)epsl;
	for(k=0;k<=epsl;k++)
	{
		putpixel(int(x+0.5),(int)(y+0.5));
		x+=xIncre;
		y+=yIncre;
	}
}

void display()
 {
     glClear(GL_COLOR_BUFFER_BIT);       
     DDALine(0,0,8,6);    
 }
 
 int main(int argc,char** argv)
 {

     glutInit(&argc,argv);
     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);  
     glutInitWindowSize(400,400);   
     glutInitWindowPosition(0,0);    
     glutCreateWindow("DDA画直线");   
     glutDisplayFunc(display);    
     init();       
     glutMainLoop();   
 
     return 0;
 }

运行结果：