#include <GL/glut.h>#include <iostream>#include <cmath>using namespace std;const GLsizei width=640;const GLsizei height=480;//設置窗口的寬和高void myInit(){  glClearColor(0,0,0,0);}void show(){  GLsizei dw;  int n,i;  dw=2;  n=(width-1)/dw;  cout<<"n="<<n<<endl;  glClear(GL_COLOR_BUFFER_BIT);  GLsizei r,g,b;  for (i=0;i<n;i++)  {    //繪制應力云圖的關鍵就是下面的這五種不同的顏色對應關系    //根據自己需要可以設置不同的等級，四種也是可以的    if (i>=0&&i<=n/5)    {      r=255;      g=i*255/(n/5);      b=0;    }    else if (i>n/5&&i<=2*n/5)    {      r=255-(i-n/5)*255/(n/5);      g=255;      b=0;    }    else if(i>2*n/5&&i<=3*n/5)    {      r=0;      g=255;      b=(i-2*n/5)*255/(n/5);    }    else if(i>3*n/5&&i<=4*n/5)    {      r=0;      g=255-(i-3*n/5)*255/(n/5);      b=255;    }    else    {      r=(i-4*n/5)*255/(n/5);      g=0;      b=255;    }    glColor3f(r/255.0f,g/255.0f,b/255.0f);    glRectf(1.0*i*dw,0.0,1.0*(i+1)*dw,height);  }  glFlush();}void reshape(int w,int h){  glViewport(0,0,(GLsizei)w,(GLsizei)h);  glMatrixMode(GL_PROJECTION);  glLoadIdentity();  glOrtho(0,w,0,h,-100,100);//設置視野的范圍，(左,右,上,下,前,后)  glMatrixMode(GL_MODELVIEW);  glLoadIdentity();}int main(int argc,char *argv[]){  glutInit(&argc, argv);  glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);  glutInitWindowPosition(100,100);  glutInitWindowSize(width,height);  glutCreateWindow("應力云圖繪制");  myInit();  glutDisplayFunc(show);  glutReshapeFunc(reshape);  glutMainLoop();  return 0;}