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

int width = 800;
int height = 600;

void init(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE);
    glutInitWindowSize(width, height);
    glutInitWindowPosition(100, 100);
    glViewport(0, 0, width, height);
    glutCreateWindow("Culling");
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
    glOrtho(-2.0, 2.0, -2.0, 2.0, -2.0, 2.0);
    gluLookAt(0.25, 0.5, 0.1, 0, 0, 0, 0, 1, 0);

    ////////////////////////////////////////////////////////////////////

    glEnable(GL_CULL_FACE);
    glCullFace(GL_FRONT);

    ////////////////////////////////////////////////////////////////////
}

void display(void)
{

    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);

    glBegin(GL_QUADS);

    glColor3f(1.0f, 0.0f, 0.0f);
    // FRONT
    glVertex3f(-0.5f, -0.5f, 0.5f);
    glVertex3f(0.5f, -0.5f, 0.5f);
    glVertex3f(0.5f, 0.5f, 0.5f);
    glVertex3f(-0.5f, 0.5f, 0.5f);
    // BACK
    glVertex3f(-0.5f, -0.5f, -0.5f);
    glVertex3f(-0.5f, 0.5f, -0.5f);
    glVertex3f(0.5f, 0.5f, -0.5f);
    glVertex3f(0.5f, -0.5f, -0.5f);

    glColor3f(0.0f, 1.0f, 0.0f);
    // LEFT
    glVertex3f(-0.5f, -0.5f, 0.5f);
    glVertex3f(-0.5f, 0.5f, 0.5f);
    glVertex3f(-0.5f, 0.5f, -0.5f);
    glVertex3f(-0.5f, -0.5f, -0.5f);
    // RIGHT
    glVertex3f(0.5f, -0.5f, -0.5f);
    glVertex3f(0.5f, 0.5f, -0.5f);
    glVertex3f(0.5f, 0.5f, 0.5f);
    glVertex3f(0.5f, -0.5f, 0.5f);

    glColor3f(0.0f, 0.0f, 1.0f);
    // BOTTOM
    glVertex3f(-0.5f, -0.5f, 0.5f);
    glVertex3f(-0.5f, -0.5f, -0.5f);
    glVertex3f(0.5f, -0.5f, -0.5f);
    glVertex3f(0.5f, -0.5f, 0.5f);
    glEnd();

    glFlush();
}

int main(int argc, char** argv)
{
    init(argc, argv);
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}