Hello,
so I am using a plane to cut / split meshes. The split method returns an array of meshes, but I want to determine which parts of the meshes are on which side of the plane. Generally speaking, when you cut an object, you get two pieces. Is there any structure within the returned array that gives me information about this specific problem.
Is there any order of the meshes inside the array at all?
Or are the meshes just “randomly” thrown together and then returned as an array?
No, there is not. You will need to evaluate each mesh piece to determine what to keep and what to toss away.
– Dale
If you use a Box as a cutter, or at least let the Box follow the cutter (exactly on top of the plane or underneath) and then test which parts are inside the Box. Keep or discard those.
I just did that trick yesterday. Below I show how the box follows the cutting plane. It’s sharp. I cuts even to the bones. 
// Rolf
Ok, thanks.
That’s a nice trick, I’ll see if I can make use of this.