//initialize openGL
void initOpenGL()
{
	glEnable( GL_TEXTURE_2D );

	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );

	glViewport( 0, 0, screen->w, screen->h );

	glClear( GL_COLOR_BUFFER_BIT );

	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();

	glOrtho(0.0f, screen->w, screen->h, 0.0f, -1.0f, 1.0f);

	glMatrixMode( GL_MODELVIEW );
	glLoadIdentity();


	return;
}