CGAL users discussion list

[Giles Puckett <>]

Hello,

I have an application that builds 3D volumes by combining simple shapes 
(cubes, cylinders) using corefine_and_compute_union. There may be 
100-400 simple shapes.

I tried two ways of doing the unions:

1. Build up the result by unioning in one cube at a time, or

2. Union the simple shapes in pairs, then union their results (in a 
binary tree fashion) until you get one object left.

I noticed that method 2 is a lot slower than method 1 - I assumed it was 
because there are many more faces to be split when corefining. Is this a 
reasonable assumption? I am interested in method 2 again as it lends 
itself to doing unions in parallel, potentially reducing operations from 
O(N) to O(log2 N) if there are enough cores/threads.

What determines the performance if corefine_and_compute_union? Is it the 
complexity of the meshes, the complexity of the intersection path, or 
something else?

And is PMP able to be multithreaded?

Giles.