计算机图形学——绘制钻石图案

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要求：绘制钻石图案。将一圆周进行n等分，然后将所有的等分用直线连接，构成图案。

n=8

q =2*p/n

X=2*r*cos(q)

Y=r*sin(q)

#include <GL/glut.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#define pi 3.14159265
int n=8;
int R=200,CX=250,CY=250;
int *point;
void initGraph(void);
void drawCircle(int cx, int cy, int r);
void display(void);
void drawLine(int x1, int y1, int x2, int y2);
void main(int argc, char **argv){
     float w,wi;
     glutInit(&argc,argv);
     glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB) ;
     glutInitWindowSize(500,500);
     glutCreateWindow("n阶钻石图案");
     initGraph();
point=(int*)malloc(sizeof(int)*n*2);//申请存储空间
w=2*pi/n;
wi=w/2;
for(int i=0;i<2*n;i+=2){
point[i]=(int)(CX+R*cos(wi));
point[i+1]=(int)(CY+R*sin(wi));
wi+=w;
}
    glutDisplayFunc(display);
    glutMainLoop();
    if(point!=NULL)free(point);//释放存储空间
}
void initGraph (void){
    glClearColor(0.0,0.0,0.0,0.0);
    gluOrtho2D(0.0,500.0,0.0,500.0);//窗口坐标左下角(0,0), 右上角(500,500)
}
void display(void){
     glClear(GL_COLOR_BUFFER_BIT) ;
     glColor3f(5.0, 3.0, 4.0) ;
     for(int i=0;i<2*n-2;i+=2){
          for(int j=i+2;j<2*n;j+=2){
              drawLine(point[i],point[i+1],point[j],point[j+1]); 
          }
    }
}
 
void drawLine(int x1, int y1, int x2, int y2) {
    glBegin(GL_LINES);
    glVertex2d(x1, y1);
    glVertex2d(x2, y2);
    glEnd();
    glFlush() ;
}