#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 Display(void){glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口glColor3f(1.0f, 0.0f, 0.0f); //设置当前的绘图颜色为红色glRectf(50.0f, 100.0f, 150.0f, 50.0f); //绘制一个矩形 glFlush(); //处理所有的OpenGL程序}*/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);elseepsl=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;}elsed += 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;}
