   Shadow Mapping Algorithm/Implementation problem
  Hi, I want to add shadows to my engine, so I decided to use shadow mapping or projective texture mapping (I think these two are similar if not the same thing). So, what I understand is that1) I render the scene from the light's point of view into a shadow map2) I render the scene from eye's view,3) now I would like to project the shadow map over the scene and draw the shadows I don't know how to do step 3).  Is it posible to do something like that, or I didn't understand the whole process ? And if so, is it possible to draw the shadows without having to modify the vertex/pixel shaders that draw the scene, but write new shaders that do shadow map projection and shadow drawing ?   
  Anyone, any ideea ?   ;  In one of the versions of the SDK there is a shadowmap example, to save the trouble I uploaded it..http://matrix.senecac.on.ca/~jlsawchu/shadows/   