/* Paul Solt
 * A simple setup for the CG2 Ray tracing scene positional values.
 * 3-20-07
 */
#include <stdlib.h>
#include <stdio.h>
#include <GL/glut.h>

GLint width = 500; /* 1.6 aspect ratio */
GLint height = 300;

/* Prototypes */
void init();
void display();
void draw();
void timer();
void keyboard( unsigned char key, int x, int y );	

void init() {
	glShadeModel( GL_FLAT );
	glClearColor( 0.0, 0.0, 0.0, 1.0 );
}

void display() {

	glClear( GL_COLOR_BUFFER_BIT );
	/* Don't need reshape with these function calls */
	width = glutGet( GLUT_WINDOW_WIDTH );
	height = glutGet( GLUT_WINDOW_HEIGHT );
	GLfloat aspectRatio;
	
	if( height > 0 ) { /* Make sure it's not minimized */
		aspectRatio = (double)width/height;
		/* Setup the projection and model view matricies */
		glViewport( 0, 0, width, height );
		glMatrixMode( GL_PROJECTION );
		glLoadIdentity();
		gluPerspective( 60, aspectRatio, 1.0, 40.0 );
		glMatrixMode( GL_MODELVIEW );
		glLoadIdentity();
		gluLookAt( 0.0, 1.0, -1.0, 0.0, 0.0, 10.0, 0.0, 1.0, 0.0 );
	
		draw();
		glutSwapBuffers();
	}	
}

/* Draw the objects */
void draw() {
	glBegin( GL_QUADS ); { /* Create the floor */
		glColor3f( 1.0, 0.0, 0.0 );
		glVertex3f( -5.1, 0.0, 10.0 );
		glVertex3f( 1.70, 0.0, 10.0 );
		glVertex3f( 1.45, 0.0, 0.0 );
		glVertex3f( -4.6, 0.0, 0.0 );
	} glEnd();
	
	glPushMatrix(); { /* draw the background sphere */
		glColor3f( 0.0, 0.8, 6.0 );
		glTranslated( -1.3, 0.46, 3.10 );
		glutSolidSphere( 1.00, 40, 40 );
	} glPopMatrix();
	glPushMatrix(); { /* draw the forground sphere */
		glColor3f( 0.0, 0.4, 1.0 );
		glTranslated( 0.05, 1.08, 0.45 );
		glutSolidSphere( 0.50, 40, 40 );
	} glPopMatrix();
}

/* Redraw the scene every 10 milliseconds */
void timer( int value ) {
	glutPostRedisplay();
	glutTimerFunc( 10, timer, 0 );
}

/* Exit when the escape key is pressed */
void keyboard( unsigned char key, int x, int y ) {
	switch( key ) {
		case 27: /* Escape key pressed */
			exit(1);
			break;
		default:
			break;
	}
}

int main( int argc, char *argv[] ) {
	glutInit( &argc, argv );
	glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
	glutInitWindowPosition( 200, 200 );
	glutInitWindowSize( width, height ); 
	glutCreateWindow( argv[0] );
	init();
	glutDisplayFunc( display );  /* call back functions */
	glutTimerFunc( 10, timer, 0 );
	glutKeyboardFunc( keyboard );
	glutMainLoop();
	return 0;
}