Back projecting shadow maps


Does anyone know an easy (and fast) way to eliminate back projecting shadows when using the shadow map algorithm? I need a detailed description in order to understand it (I’ve read about it, but don’t understand how to do it.)

My problem is a scene with a pointlight in the middle and an occluder which in addition to casting shadow the right way - also casts a shadow on the other side of the light!

I hope someone can help me!

  • Monica

You can use a clipplane, like this :

Assuming the light is L, and light direction is D .,

A = D.x;
B = D.y;
C = D.z;
D = -Dot(D,L);

Now just feed those values to the clipplane.