/*
	CSCI 250 Fall 2002 Sample Z-buffer program
	Author: Don Allison (with help from OpenGL refs/web sites)
	Date: 4 October 2002
*/

#include <GL/glut.h>

/* light colors and positions */

GLfloat ambient[] = {0.2, 0.2, 0.2, 1.0};
GLfloat red_diffuse[] = {1.0, 0.0, 0.0, 1.0};
GLfloat green_diffuse[] = {0.0, 1.0, 0.0, 1.0};
GLfloat blue_diffuse[] = {0.0, 0.0, 1.0, 1.0};
GLfloat position1[] = {10.0, 10.0, 10.0, 0.0};
GLfloat position2[] = {-10.0, -10.0, -10.0, 0.0};
GLfloat position3[] = {-10.0, 10.0, 10.0, 0.0};

/* object colors */

GLfloat cyan[] = {0.0, 0.8, 0.8, 1.0};
GLfloat magenta[] = {0.8, 0.0, 0.8, 1.0};
GLfloat yellow[] = {0.8, 0.8, 0.0, 1.0};



void init(void)
{
// set clear color

	glClearColor(0.0, 0.0, 0.0, 0.0);

// drawing setup

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	glEnable(GL_DEPTH_TEST);

// specify lights

	glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, red_diffuse);
	glLightfv(GL_LIGHT0, GL_POSITION, position1);

	glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
	glLightfv(GL_LIGHT1, GL_DIFFUSE, green_diffuse);
	glLightfv(GL_LIGHT1, GL_POSITION, position2);

	glLightfv(GL_LIGHT2, GL_AMBIENT, ambient);
	glLightfv(GL_LIGHT2, GL_DIFFUSE, blue_diffuse);
	glLightfv(GL_LIGHT2, GL_POSITION, position3);

	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_LIGHT1);
	glEnable(GL_LIGHT2);

}




void display(void)
{
// clear display and depth buffer

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


// draw two spheres

	glMatrixMode(GL_MODELVIEW);

	glMaterialfv(GL_FRONT, GL_AMBIENT, cyan);
	glMaterialfv(GL_FRONT, GL_DIFFUSE, cyan);
	glMaterialfv(GL_FRONT, GL_SPECULAR, cyan);
	glMaterialf(GL_FRONT, GL_SHININESS, 1000.0);

	glPushMatrix();
	glTranslatef(2.0, 5.0, 2.0);
	glutSolidSphere(1.0, 10, 10);
	glPopMatrix();

	glMaterialfv(GL_FRONT, GL_AMBIENT, yellow);
	glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow);
	glMaterialfv(GL_FRONT, GL_SPECULAR, yellow);
	glMaterialf(GL_FRONT, GL_SHININESS, 100000.0);

	glPushMatrix();
	glTranslatef(-2.0, 2.0, -2.0);
	glutSolidSphere(1.5, 10, 10);
	glPopMatrix();

// draw plane

	glMaterialfv(GL_FRONT, GL_AMBIENT, magenta);
	glMaterialfv(GL_FRONT, GL_DIFFUSE, magenta);
	glMaterialfv(GL_FRONT, GL_SPECULAR, magenta);
	glMaterialf(GL_FRONT, GL_SHININESS, 100.0);

	glBegin(GL_POLYGON);
		glVertex3f(-5.0, 0.0, -5.0);
		glVertex3f(-5.0, 0.0, 5.0);
		glVertex3f(5.0, 0.0, 5.0);
		glVertex3f(5.0, 0.0, -5.0);
	glEnd();

// flip buffers so one were drawing in is now displayed

	glutSwapBuffers();

}


void resize_window(int w, int h) 
{
// set up viewport and perspective projection

	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective (45.0, 5.0/4.0, 0.1, 200.0); 

// now set up the eye position

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
  	gluLookAt(-10.0, 10.0, 5.0,	// from
		0.0, 2.0, 0.0,			// at
		0.0, 1.0, 0.0);			// up


 }

int main(int argc, char ** argv)
{
// standard glut stuff

	glutInit(&argc, argv);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(500, 500);
	glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
	glutCreateWindow("zbuffer sample");

	init();

	glutReshapeFunc(resize_window);
	glutDisplayFunc(display);

	glutMainLoop();

	return 0;
}