varying mat4 v_tex_rot;

void main() {
	vec4 l_position = gl_Vertex;
	vec2 l_direction = normalize(vec2(l_position.z, l_position.w));
	v_tex_rot = mat4(l_direction.x, l_direction.y, 0.0, 0.0,
					-l_direction.y, l_direction.x, 0.0, 0.0,
					0.0, 0.0, 1.0, 0.0,
					0.0, 0.0, 0.0, 1.0);
	l_position.z = 0.0;
	l_position.w = 1.0;
	gl_FrontColor = gl_Color;
	gl_Position = gl_ModelViewProjectionMatrix * l_position;
}