A Sample using GLUT

This is a sample of a moving cube:

#include <iostream>
#include <GL/glut.h>
#include <cstdlib>

using namespace std;
static GLfloat spin=0.0;
void init(void){
 glClearColor(0.0,0.0,0.0,0.0);
 glShadeModel(GL_FLAT);
}
void display(void){
 glClear(GL_COLOR_BUFFER_BIT);
 glPushMatrix();
 glRotatef(spin,0.0,0.0,1.0);
 glColor3f(1.0,1.0,1.0);
 glRectf(-25.0,-25.0,25.0,25.0);
 glPopMatrix();
 glutSwapBuffers();
}
void spinDisplay(void){
 spin=spin+1.5;
 if(spin>360.0)
  spin=spin-360.0;
 glutPostRedisplay();
}
void reshape(int w, int h){
 glViewport(0,0,(GLsizei)w,(GLsizei)h);
 glMatrixMode(GL_PROJECTION);
 glLoadIdentity();
 glOrtho(-50.0,50.0,-50.0,50.0,-1.0,1.0);
 glMatrixMode(GL_MODELVIEW);
 glLoadIdentity();
}
void mouse(int button, int state, int x, int y){
 switch(button){
 case GLUT_LEFT_BUTTON:
  if (state==GLUT_DOWN)
   glutIdleFunc(spinDisplay);
  break;
 case GLUT_RIGHT_BUTTON:
  if (state==GLUT_DOWN)
   glutIdleFunc(NULL);
  break;
 default:
  break;
 }
}
int main(int argc, char** argv){
 glutInit(&argc,argv);
 glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
 glutInitWindowSize(250,250);
 glutInitWindowPosition(100,100);
 glutCreateWindow(argv[0]);
 init();
 glutDisplayFunc(display);
 glutReshapeFunc(reshape);
 glutMouseFunc(mouse);
 glutMainLoop();
 return 0;
}