// for use with glVeiwport
const int GL_VP_X = 0;
const int GL_VP_Y = 1;
const int GL_VP_W = 2;
const int GL_VP_H = 3;

Line3f GetPickLine( void ) {
	const int* vp = game->renderer.viewport;

	// map UI mouse pos to [-1,1]
	Vec3f pos( game->input.GetUIMousePos() );
	pos.x = 2 * pos.x / vp[GL_VP_W] - 1; // todo * aspectRatio
	pos.y = 1 - 2 * pos.y / vp[GL_VP_H]; // invert y axis

	// get the inverted modelViewProjection matrix
	Mat4f mv( game->renderer.modelMatrix );
	Mat4f mvpi = Mat4f( game->renderer.projectionMatrix ) * mv;
	mvpi.InvertRotationOrtho();
	mvpi.InvertTranspositionOrtho();

	// multiply mouse pos and modelViewProjection matrix to get a point on that ray
	pos = mvpi * pos;

	Vec3f cam( -mv.Column3f(3) ); // camera position is last column of modelView matrix
	return Line3f( cam, pos );
}

Line3f GetPickLine( void ) {
    const int* vp = game->renderer.viewport;

    // map UI mouse pos to [-1,1]
    Vec3f pos( game->input.GetUIMousePos() );
    pos.x = 2 * pos.x / vp[GL_VP_W] - 1; // todo * aspectRatio
    pos.y = 1 - 2 * pos.y / vp[GL_VP_H]; // invert y axis

    // get the inverted modelViewProjection matrix
    Mat4f mv( game->renderer.modelMatrix );
    Mat4f mvpi = Mat4f( game->renderer.projectionMatrix ) * mv;
    mvpi.InvertRotationOrtho();
    mvpi.InvertTranspositionOrtho();

    // multiply mouse pos and modelViewProjection matrix to get a point on that ray
    pos = mvpi * pos;

    Vec3f cam( -mv.Column3f(3) ); // camera position is last column of modelView matrix
    return Line3f( cam, pos );
}