#include "GL/glut.h"


volatile unsigned long long int timer_ticks = 0;

/// Displays a square based pyramid from a base position, height and side length
/// \param x X coordinate of the center
/// \param y Y coordinate of the center
/// \param z Z coordinate of the center
/// \param c Side length of the square
/// \param h Height of the pyramid
void display_pyramid(float x, float y, float z, float c, float h)
{
    glBegin(GL_TRIANGLES);

    // First side
    glColor3f(1,0,0);

    // Summit
    glVertex3f(x,y+h,z);
    glVertex3f(x+c/2,y,z+c/2);
    glVertex3f(x-c/2,y,z+c/2);

    // Second side
    glColor3f(0,1,0);

    glVertex3f(x,y+h,z);
    glVertex3f(x+c/2,y,z+c/2);
    glVertex3f(x+c/2,y,z-c/2);

    // Third side
    glColor3f(0,0,1);

    glVertex3f(x,y+h,z);
    glVertex3f(x-c/2,y,z+c/2);
    glVertex3f(x-c/2,y,z-c/2);

    // Fourth side
    glColor3f(1,1,0);

    glVertex3f(x,y+h,z);
    glVertex3f(x-c/2,y,z-c/2);
    glVertex3f(x+c/2,y,z-c/2);

    glEnd();
    // Bottom
    glBegin(GL_QUADS);

    glColor3f(0,1,1);
    glVertex3f(x-c/2,y,z-c/2);
    glVertex3f(x-c/2,y,z+c/2);
    glVertex3f(x+c/2,y,z+c/2);
    glVertex3f(x+c/2,y,z-c/2);

    glEnd();
}

/// Draw a pyramid rotated around its axis
void display_rotating_pyramid(float x, float y, float z, float c, float h, float alpha)
{
    glPushMatrix();
    glTranslatef(x,0,z);
    glRotatef(alpha,0,1,0);
    glTranslatef(-x,0,-z);
    display_pyramid(x,y,z,c,h);
    glPopMatrix();
}

void display()
{
    float angleY = 1*timer_ticks;
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION);
    // Prepare view
    glLoadIdentity();
    gluPerspective(60,(double)glutGet(GLUT_WINDOW_WIDTH)/(double)glutGet(GLUT_WINDOW_HEIGHT),10,30000);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(10, 10, 10,
              0, 0, 1,
              0, 1, 0);


    display_rotating_pyramid(0,-2,0,2,4,angleY);
    display_rotating_pyramid(3,-2,0,1,5,angleY);
    display_rotating_pyramid(-2,-2,4,3,2,angleY);

    glutSwapBuffers();
}

void update_angle(int value)
{
    timer_ticks++;
    glutTimerFunc(50,update_angle,0);
}

int main(int argc, char** argv)
{
    glutInit(&argc,argv);
    // Generate window with GLUT
    glutInitDisplayMode(GLUT_RGB| GLUT_DEPTH | GLUT_DOUBLE);
    glutCreateWindow("Hello");

    // Init OpenGL
    glClearColor(0,0,0,1);
    glClearDepth(1.0);
//    glEnable(GL_LIGHTING);
//    glEnable(GL_LIGHT0);
    glEnable(GL_DEPTH_TEST);

    glViewport(0,0,glutGet(GLUT_WINDOW_WIDTH),glutGet(GLUT_WINDOW_HEIGHT));

    glutIdleFunc(display);
    glutTimerFunc(50,update_angle,0);

    // Enters main loop, managed by GLUT
    glutMainLoop();
	return 0;
}