2D outline algorithm for projected 3D mesh

Question

Given: A 3D mesh defined with a set of vertices and triangles building up the mesh with these points.

Problem: Find the 2d outline of the projected arbitrarily rotated m

Answer 1

Just to add: A very intuitive way to find edges in a projection is back face culling! Any edge between a culled and non-culled face should be an outline. If you want to hide interior edges, just use the z-buffer. Back face culling is simply the post projection vertex order and very cheap to compute.