void player_update()
{	
	GLfloat v[3] = {	player.lx - player.x,
						player.ly - player.y,
						player.lz - player.z};
	
	GLfloat * c = player.matrix;
	GLfloat * v1 = player.velocity;
	GLfloat v2[2];
	
	/* multiply the view vector by the transformation matrix */
	v[0] = c[0] * v[0] + c[4] * v[1] + c[8] * v[2] + c[12];
	v[1] = c[1] * v[0] + c[5] * v[1] + c[9] * v[2] + c[13];
	v[2] = c[2] * v[0] + c[6] * v[1] + c[10] * v[2] + c[14];
		
	/* now do the same for the velocity vector except ignore any y transforms*/
	v2[0] = c[0] * v1[0] + c[8] * v1[2] + c[12];
	v2[1] = c[2] * v1[0] + c[10] * v1[2] + c[14];
	
	debug("v2=[%f, %f]", v2[0], v2[2]);
	
	player.x+=v2[0];
	player.z+=v2[1];
	player.lx+=v2[0];
	player.lz+=v2[1];
		
	sengine_lookat(player.x, 
				   player.y, 
				   player.z, 
				   player.x+v[0], 
				   player.y+v[1], 
				   player.z+v[2]);
}