/**********************************
    Computer Graphics Lab
    30/03/2010
    Zaed Murad
    unijust@unijust.com
***********************************/
#include <cmath>
#include <gl\glut.h>

    int pts***91;5***93;***91;3***93; = { {0,0,0},{4,0,0},{4,0,4},{0,0,4},{2,4,2}};
    double r = 3;
    double theta = 0.5;
    int a = 2;
    int b = 2;
    double cx = a + r * cos(theta);
    double cz = b +  r * sin(theta);
    double cy = 3.0;

    void triangle(int v1,int v2,int v3)
    {
        glBegin(GL_TRIANGLES);
            glVertex3iv(pts***91;v1***93;);
            glVertex3iv(pts***91;v2***93;);
            glVertex3iv(pts***91;v3***93;);
        glEnd();
    }

    void quad(int v1,int v2,int v3,int v4)
    {
        glBegin(GL_QUADS);
            glVertex3iv(pts***91;v1***93;);
            glVertex3iv(pts***91;v2***93;);
            glVertex3iv(pts***91;v3***93;);
            glVertex3iv(pts***91;v4***93;);
        glEnd();
    }

    void drawCube()
    {
        glColor3f(1,1,1);
        quad(0,1,2,3);
    }

    void drawTriangle()
    {
        glColor3f(0,0,1);
        triangle(0,1,4);

        glColor3f(0,1,1);
        triangle(3,2,4);

        glColor3f(1,0,1);
        triangle(2,1,4);

        glColor3f(0,1,0);
        triangle(0,3,4);
    }


    void init()
    {
        glLoadIdentity();
        gluLookAt(cx,cy,cz,2,0,2,0,1,0); // y is the up vector
        glMatrixMode(GL_PROJECTION);
        glOrtho(-7,7,-7,7,-7,7);
    }

    void drawAxis()
    {
        glBegin(GL_LINES);
            
            /******** X ********/
            glColor3f(0,1,0);
            glVertex3f(0,0,0);
            glVertex3f(5,0,0);

            /******** Y ********/
            glColor3f(1,0,0);
            glVertex3f(0,0,0);
            glVertex3f(0,5,0);

            /******** Z ********/
            glColor3f(0,0,1);
            glVertex3f(0,0,0);
            glVertex3f(0,0,5);

        glEnd();
    }



    void display()
    {
        glClearColor(0.5,0.5,0.5,0);
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

        drawAxis();
        drawCube();
        drawTriangle();

        glFlush();
    }

    void key(unsigned char c,int x,int y)
    {
        switch(c)
        {
        case 'y':
        case 'Y':
            theta -=0.0174444;
            if(theta < 0)
                theta = 2 * (22/7.0);
            break;
        case 'x':
        case 'X':
            theta +=0.0174444;
            if(theta > 2*(22/7))
                theta = 0;
            break;
        }
        cx = a + r * cos(theta);
        cz = b + r * sin(theta);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(cx,cy,cz,2,0,2,0,1,0); // y is the up vector
        
        display();
    }

void main(int c,char** v)
{
    glutInit(&c,v);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(400,400);
    glutCreateWindow("3D Project");
    init();
    glEnable(GL_DEPTH_TEST);
    glutKeyboardFunc(key);
    glutDisplayFunc(display);
    glutMainLoop();
}