Are there any libraries for easier editing of geometry, like splitting edges, bisecting faces, etc?

Questions
,
1

I’m interested in learning about how to implement these kind of geometry operations that 3d modelers like Blender, have, like splitting edges, bisecting faces, etc. I want to study different implementations of these 3d geometry modifier utilities. I was wondering if ThreeJS has any libraries for editing geometry? I’m aware of GitHub - gkjohnson/three-bvh-csg: A flexible, memory compact, fast and dynamic CSG implementation on top of three-mesh-bvh but it seems to be about boolean operations on geometry. I’m interested in the under-the-hood implementation of operations like:

  • splitting an edge
  • bisecting a face
  • connecting 2 vertices with an edge.

This BMesh article by Blender is interesting: BMesh - Blender Developer Documentation

The reason why I’m interested in ThreeJS is because I feel like it’d be a little bit simpler than the implementations that 3d engines like Blender or Unity have.

1 Like
2

Hi, not sure if you checked this recent post, this could be useful if you’re looking for CAD modelling algorithms

3

Another that might be worth a look would be Manifold:

It’s not specifically for three.js, but the two can certainly be used together.

1 Like
4

Hey, just wanted to share that we also expose manifold library. Here you can find short announcement:

5

Half edges are pretty trivial to implement, does this require a library? Maybe for those operations.

Not sure if you’re looking for manifold meshes? Are you? Do you want to 3D print stuff or make arbitrary things that look nice, eg. a car?

2 Likes
6

I second the recommendation of half-edge data structure… It’s pretty simple but creates the necessary scaffolding for a while bunch of geometric operations.

There is an implementation in threejs also, I think added/created by Mugen.

7

Here’s a basic one:

type HalfEdge = {
  next:number,
  prev:number,
  twin:number,
  face:number,
  start:number
  end:number
}
8