Shadows different approach?

I’ve ran through NeHes tutorial about shadow casting & understood that It’s quite a long way. I’ve heard the idea that shadows can be projected to flat surfaces. I have an object & I know the light position, so I can create matrix that collapses this object on the poligon through object-light line. All I would have to do is set obj color to black & in some cases add a little transparency. That should be a lot faster & would be Ok for flat objects, but I don’t know where could I look for examples, tutors.

maybe this helps:


Shadow rendering and projection onto planes using glScale is usually frowned upon, is it not?