// gcc -o test gltest.cpp -framework OpenGL -framework GLUT (MAC)

// gcc -0 test gltest.cpp  -lGL -lGLU -lglut -lX11 (Linux)

// Need X server on windows.
// on Linux use: ssh -X user@server.edu
#ifdef __APPLE__
#include <GLUT/glut.h>
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#else
#include <GL/glut.h>
#include <GL/gl.h>
#endif

#define kWindowWidth 400
#define kWindowHeight 300

GLvoid InitGL(void);
GLvoid DrawGLScene(void);
GLvoid ReSizeGLScene(int Width, int Height);

int main(int argc, char** argv)
{
 	glutInit(&argc, argv);
 	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
 	glutInitWindowSize (kWindowWidth, kWindowHeight);
 	glutInitWindowPosition (100, 100);
 	glutCreateWindow (argv[0]);

 	InitGL();

 	glutDisplayFunc(DrawGLScene);
 	glutReshapeFunc(ReSizeGLScene);

 	glutMainLoop();

 	return 0;
}

GLvoid ReSizeGLScene(int width, int height)
{
 	if(height == 0)
 	{
 		height = 1;
 	}

 	glViewport(0, 0, width, height);

 	glMatrixMode(GL_PROJECTION);
 	glLoadIdentity();
 	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

 	glMatrixMode(GL_MODELVIEW);
 	glLoadIdentity();
}

GLvoid InitGL(void)
{
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 	glClearDepth(1.0f);
 	glEnable(GL_DEPTH_TEST);
}

GLvoid DrawGLScene(void)
{
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 	glLoadIdentity();

 	glTranslatef(-1.5f, 0.0f, -6.0f);
 	glColor3f(1.0, 0.0, 0.0);

 	glBegin(GL_TRIANGLES);
 		glVertex3f( 0.0f, 1.0f, 0.0f);
 		glVertex3f(-1.0f,-1.0f, 0.0f);
 		glVertex3f( 1.0f,-1.0f, 0.0f);
 	glEnd();

 	glTranslatef(1.0, 1.0, 1.0);
 	glColor3f(0.0, 1.0, 0.0);

 	glBegin(GL_QUADS);
 		glVertex3f(-1.0f, 1.0f, 0.0f);
 		glVertex3f( 1.0f, 1.0f, 0.0f);
 		glVertex3f( 1.0f,-1.0f, 0.0f);
 		glVertex3f(-1.0f,-1.0f, 0.0f);
 	glEnd();

	glTranslatef(1.0, 1.0, 1.0);
 	glColor3f(1.0, 1.0, 0.0);

	glBegin(GL_POLYGON);
 		glVertex3f( 0.0f, 0.0f, 0.0f);
 		glVertex3f( 1.0f, 0.0f, 0.0f);
 		glVertex3f( 2.0f,-1.0f, 0.0f);
 		glVertex3f( 1.0f, 2.0f, 0.0f);
		glVertex3f( 0.0f, 2.0f, 0.0f);
 		glVertex3f(-1.0f,-1.0f, 0.0f);
 	glEnd();

 	glutSwapBuffers();
}