#include <stdlib.h>

#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

// Question 1: In a GLUT program, how is control passed
// back to the programmer?  How is this set up during
// initialization?

int win_width = 512,
    win_height = 512;

void display( void )
{
	glClear( GL_COLOR_BUFFER_BIT );

	glutSwapBuffers();
}

void reshape( int w, int h )
{
	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	
	// Question 3: What do the calls to glOrtho()
	// and glViewport() accomplish?
	glOrtho( 0., 1., 0., 1., -1., 1. );
	glViewport( 0, 0, w, h );
	
	win_width = w;
	win_height = h;

	glutPostRedisplay();
}

void keyboard( unsigned char key, int x, int y ) {
	switch(key) {
		case 27: // Escape key
			exit(0);
			break;
	}
}

int main (int argc, char *argv[]) {
	
	glutInit( &argc, argv );
	// Question 2: What does the parameter to glutInitDisplayMode()
	// specify?
	glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
	glutInitWindowSize( win_width, win_height );
	
	glutCreateWindow( "Intro Graphics Assignment 1" );
	
	glutDisplayFunc( display );
	glutReshapeFunc( reshape );
	glutKeyboardFunc( keyboard );

	glutMainLoop();
}