Problem for you, /prog/

If you have convex polyhedron represented by a bunch of planes in hessian normal form, how do you calculate its outline along the the z-plane (in z-up), i.e. how its shadow would look on the ground if the sun were directly above it.

>>1

Project each face of the polyhedron onto the plane. The shadow will be the collective overlap of all of these planes. For plus plus efficiency, you could do it for only the faces that face the light source. For rendering the shadow, you could either render each plan projection, or you could merge them somehow.

Another method could be to take all verteces of the polyhedron, project each down onto the plain, and then find the convex hull of the projected points.

>>3
As a result of catastrophic natural disasters it was destroyed in the film http://en.wikipedia.org/wiki/2012_movie

Convex hulls are for building ships.
Projections are for math.
>>1 http://en.wikipedia.org/wiki/Projection_%28linear_algebra%29#Projections_on_normed_vector_spaces may apply, did you read it?