When I want to draw a capped shadow volume
I proceed as outlined by lengyel in his article
for a silhouette edge I do…
take all vertices from a triangle that faces towards the light
extrude all vertices from a triangle that faces away from the light to infinity with respect to the light direction
Until now I add those vertices into my List of vertices making up the silhouette …
but It is said that the shadow volume should be closed should I therefore insert the vertices in such a way that I get some polygon formed by the front cap, back cap and sideplanes closing the front and back cap
or is it totally sufficient to inseert the vertices to have a triangle that represents the front cap and the vertices to have a back cap.
instead. Since in (1) I get shadow quads starting at the origin and pointing to some V’
but according to my understanding I want a Shadow Quad V’
starting at the V and pointing to V’
Extruded silhouette polys should go from their original location V to their projected location V’. How you compute V’ depends on whether V and L are expressed in general homogeneous coordinates (V.w != 1). You need a more general expression if they are.
Otherwise it looks like you’re on the right track.