本文实例为大家分享了OpenGL绘制直线和圆的具体代码，供大家参考，具体内容如下

#include <gl/glut.h>#include <math.h> static int i=1; void Initial(void){ glClearColor(1.0f, 1.0f, 1.0f, 1.0f); //设置窗口背景颜色为白色 glMatrixMode(GL_PROJECTION); //指定设置投影参数 gluOrtho2D(-200.0,200.0,-200.0,200.0); //设置投影参数 //指的是视图范围，如果(0,200,0,200)的话就只能在第一象限显示，就1/4圆，第1，3的参数是左下角坐标，第2，4的参数是右上角坐标} void DDALine(int x0,int y0,int x1,int y1){ //glVertex2f(10,10); 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; glPointSize(2); glBegin(GL_POINTS); for(k = 0;k <= epsl; k++) { glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(int(x+0.5),int(y+0.5)); x += xIncre; y += yIncre; } glEnd(); } void Mid_B(int x0,int y0,int x1,int y1){ int dx,dy,d,UpIncre,DownIncre,x,y; if(x0 > x1) { x = x1; x1 = x0; x0 = x; y = y1; y1 = y0; y0 = y; } x = x0; y = y0; dx = x1 - x0; dy = y1 - y0; d = dx - 2*dy; UpIncre = 2*dx - 2*dy; DownIncre =- 2*dy; glPointSize(2); glBegin(GL_POINTS); while(x <= x1) { glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(x,y); x++; if(d < 0) { y++; d += UpIncre; } else d += DownIncre; } glEnd(); } void G_B(int x0,int y0,int x1,int y1){ int x,y,dx,dy,e; dx = x1 - x0; dy = y1 - y0; e =- dx; x=x0; y=y0; glPointSize(2); glBegin(GL_POINTS); while(x <= x1) { glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(x,y); x++; e = e + 2*dy; if(e > 0) { y++; e = e - 2*dx; } } glEnd();} void CirclePoint(int x, int y){ glPointSize(2); glBegin(GL_POINTS); glColor3f(1.0f, 0.0f, 0.0f); glVertex2f(x,y); glVertex2f(y,x); glVertex2f(-y,x); glVertex2f(-x,y); glVertex2f(-x,-y); glVertex2f(-y,-x); glVertex2f(y,-x); glVertex2f(x,-y); glEnd();} void MidBresenhamCircle(int r){ int x = 0, y = r, d = 1-r; //glPointSize(2); //glBegin(GL_POINTS); while(x <= y) { CirclePoint(x,y); if(d < 0) d += 2*x+3; else { d += 2*(x-y)+5; y--; } x++; } glEnd();} void ProcessMenu(int value){ i = value; glutPostRedisplay();} void Display(void){ glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口 glViewport(0,0,400,400); //前两个参数改变原点坐标，后两个参数改变图形长宽（放大缩小） switch(i) { case 1: DDALine(2,3,55,83); break; case 2: Mid_B(2,3,55,83); break; case 3: G_B(2,3,55,83); break; case 4: MidBresenhamCircle(50); break; } glFlush(); } int main(int argc, char* argv[]) { glutInit(&argc, argv); //初始化GLUT库,处理命令行参数 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //初始化窗口的显示模式 glutInitWindowSize(400,400); //设置窗口的尺寸 glutInitWindowPosition(100,100); //设置窗口的位置 glutCreateWindow("直线"); //创建一个名为矩形的窗口 int MainMenu = glutCreateMenu(ProcessMenu); //创建主菜单 glutAddMenuEntry("DDA算法",1); glutAddMenuEntry("中点Bresenham算法",2); glutAddMenuEntry("改进的Bresenham算法",3); glutAddMenuEntry("中点bresenham画圆",4); glutAttachMenu(GLUT_RIGHT_BUTTON); glutDisplayFunc(Display); //设置当前窗口的显示回调函数 Initial(); //完成窗口初始化 glutMainLoop(); //启动主GLUT事件处理循环 return 0; }

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