#define APP_NAME                "Simple Objects"

#include <stdio.h>
#include "glut.h"


/* window width and height */
int winW = 640;
int winH = 480;


void drawScene (void)
{
	
	// green terrain

	glColor3f (0.0, 0.4 , 0.0);	

    glBegin(GL_QUADS);
		
		glVertex3f(-20,0,20);

		glVertex3f(-20,0,-20);

		glVertex3f(20,0,-20);

		glVertex3f(20,0,20);
	glEnd;	

	

}


void drawAxis (void)
{
    glColor3f (0.5, 0.5, 0.5);
    glBegin (GL_LINES);
        glColor3f (0.5, 0.0, 0.0);
        glVertex3f (-20.0, 0.0, 0.0);
        glVertex3f (20.0, 0.0, 0.0);

        glColor3f (0.0, 0.5, 0.0);
        glVertex3f (0.0, 20.0, 0.0);
        glVertex3f (0.0, -20.0, 0.0);

        glColor3f (0.0, 0.0, 0.5);
        glVertex3f (0.0, 0.0, -20.0);
        glVertex3f (0.0, 0.0, 20.0);
    glEnd ();
}

/*
=============
glutDisplay
=============

The display function. 
*/
void glutDisplay (void)
{
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();

    /* move our eye position away */
    glTranslatef (0, -10, -25);	  
    
	/* apply rotation */
    glRotatef (0, 1.0, 0.0, 0.0); 
    glRotatef (0, 0.0, 1.0, 0.0);

    drawAxis ();
    drawScene();
	//drawSphere();

    glutSwapBuffers();
}

void glutResize (int w, int h)
{	
    winW = w;
    winH = h;

    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport (0, 0, winW, winH);

    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();

    gluPerspective (90, winW / winH, 1, 9999);

    glutPostRedisplay ();
}


void glInit (void)
{
    glEnable (GL_DEPTH_TEST);
	glClearDepth(1.0);
}

int main (void)
{
    glutInitDisplayMode (GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize (winW,winH);
    glutCreateWindow (APP_NAME);
    glutDisplayFunc (glutDisplay);
    glutReshapeFunc (glutResize);
    
    glInit ();
    glutMainLoop();

	return 1;
}