You'll need to generate a texture that you can use to warp UVs Conveniently you can previs that in designer using the warp/vector warp nodes. Recreating the warp/vector warp maths in an unreal shader is quite simple - if you can open the node up you should be able to basically just copy the sums
Ahh in that case. I think it normally means the connecting area between the edges/verts. So a polygon is the sum of all the parts verts, edges and faces?