GL

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>

switch(state)
{
case 0:
    break;
case 1:
    glPushMatrix();
    glTranslatef(-1,0,0);
    rectangle(0,0,1,2);
    glPopMatrix();
    break;
case 2:
    glPushMatrix();
    glRotatef(rot,0,0);
    triangle();
    glPopMatrix();
    break;
case 3:
    glPushMatrix();
    glTranslatef(-0.5,-0.5,-2);
    glRotatef(-45,1,0,0);
    glRotatef(45,1,0,1);
    glTranslatef(0.5,0.5,0.5);
    glRotatef(rot*0.1,1,1,1);
    glTranslatef(-0.5,-0.5,-0.5);

    cube(1.0);
    glPopMatrix();
    break;

}
glFlush();
glutSwapBuffers();

void myKeyboardFunc(unsigned char key, int x, int y)
{
    switch(key)
    {
    case '0':
        state=0;
        break;
    case '1':
        state=1;
    case '2':
        state=2;
        flagRotate=true;
        rot=0;
        break;
    case '3':
        state=3;
        flagRotate=true;
        rot=0;
        break;
    case 's':
        flagRotate=false;
        break;
    case 27:
        exit(1);
    }
    glutPostRedisplay();
}
void animate()
{
    if (flagRotate == true)
    {
        rot=(rot+1);

    }
    glutPostRedisplay();
}
int main(int argc, char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

    glutInitWindowPosition(100,100);
    glutInitWindowSize(windowWidth,windowHeight);
    glutCreateWindow('Assignment 1');

    glShadeModel(GL_SMOOTH);
    glEnable(GL_DEPTH_TEST);

    glutDisplayFunc(display);
    glutKeyboardFunc(myKeyboardFunc);
    glutIdleFunc(animate);

    glutMainLoop();
    return 0;

}