Rotating a Color Cube

3) Write an OpenGL Program to draw a color cube and spin it using OpenGL transformation matrices.

#include<stdlib.h>
#include<GL/glut.h>

GLfloat vertices[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0},{1.0,1.0,-1.0},{-1.0,1.0,-1.0},{-1.0,-1.0,1.0},{1.0,-1.0,1.0},{1.0,1.0,1.0},{-1.0,1.0,1.0}};
GLfloat colors[][3] = {{0.0,0.0,0.0},{1.0,0.0,0.0},{1.0,0.0,0.0},{1.0,1.0,0.0},
{0.0,0.0,1.0},{1.0,0.0,1.0},{1.0,1.0,1.0},{0.0,1.0,1.0}};
static GLfloat theta[]={0.0,0.0,0.0};
GLint axis =1;
void polygon(int a, int b,int c,int d)
{
//draw a polygon via list of vertices
glBegin(GL_POLYGON);
  glColor3fv(colors[a]);
  glVertex3fv(vertices[a]);
  glColor3fv(colors[b]);
  glVertex3fv(vertices[b]);
  glColor3fv(colors[c]);
  glVertex3fv(vertices[c]);
  glColor3fv(colors[d]);
  glVertex3fv(vertices[d]);
  glEnd();
}
void colorcube(void)
{ //map vertices to faces
polygon(0,3,2,1);
polygon(2,3,7,6);
polygon(0,4,7,3);
polygon(1,2,6,5);
polygon(4,5,6,7);
polygon(0,1,5,4);
}

void display(void)
{
// display callback , clear frame buffer an Z buffer ,rotate cube and draw , swap buffer.
   glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
   glLoadIdentity();
   glRotatef(theta[0],1.0,0.0,0.0);
   glRotatef(theta[1],0.0,1.0,0.0);
   glRotatef(theta[2],0.0,0.0,1.0);
  colorcube();
  glFlush();
glutSwapBuffers();
}
void spinCube()
{
  // idle callback,spin cube 2 degreees about selected axis
   theta[axis] +=1.0;
if(theta[axis]>360.0)
theta[axis]-= 360.0;
glutPostRedisplay();
}
void mouse(int btn,int state,int x,int y)
{
//mouse calback ,select an axis about which to rotate
if(btn== GLUT_LEFT_BUTTON && state ==GLUT_DOWN) axis =0;
if(btn== GLUT_MIDDLE_BUTTON && state ==GLUT_DOWN) axis =1;
if(btn== GLUT_RIGHT_BUTTON && state ==GLUT_DOWN) axis =2;
}
void myReshape(int w,int h)
{
    glViewport(0,0,w,h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-2.0,2.0,-2.0 , 2.0, -10.0,10.0);
    glMatrixMode(GL_MODELVIEW);
}
int main(int argc,char** argv)
{
glutInit(&argc,argv);
//need both double buffering and Zbuffer
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);
glutInitWindowSize(500,500);
glutCreateWindow("Rotating a color cube ");
glutReshapeFunc(myReshape);
glutDisplayFunc(display);
glutIdleFunc(spinCube);
glutMouseFunc(mouse);
glEnable(GL_DEPTH_TEST);  //Enable hidden surface removal
glutMainLoop();
return 0;
}