Heds

A Half-Edge data structure for Unity. You can learn about Half Edge data structures here.

This library allows you to build up meshes vertex by vertex, face by face. It's not a replacement for 3D modelling tools - rather it gives you the ability to create and manipulate shapes using a fairly simple object model.

Compatibility

This library is compatible with Unity 2020.3.21f1. It doesn't hit much of the Unity API surface area, so I expect to to be reasonably future proof.

Examples

If you want to generate a sphere, you could do something like this:

var unityMesh = Icosahedron.Create()
  .Subdivide()
  .Subdivide()
  .GeometricDual()
  .Triangulate()
  .ProjectToSphere(sphereRadius)
  .ToUnityMesh();

That's all there is to it. There are loads more operations defined on the Mesh class if you want them, and you can easily define your own.

Suppose you want something like the above, but you need two meshes:

• A logical mesh, where faces are hexagons and pentagons, and you can use the object model to easily navigate the mesh
• A physical mesh, which is like the logical mesh but the faces have been broken down into triangles so unity can render it

You could do that like this:

var logicalMesh = Icosahedron.Create()
  .Subdivide()
  .Subdivide()
  .GeometricDual()
  .ProjecToSphere(sphereRadius);

var unityMesh = logicalMesh
  .Clone()
  .Triangulate()
  .ToUnityMesh();

Or if you want to generate a sphere based on a cube instead of an icosahedron:

var unityMesh = QuadCube.Create()
  .Triangulate()
  .Subdivide()
  .Subdivide()
  .ProjectToSphere(sphere)
  .ToUnityMesh();

Custom shapes

If you want to generate your own shape instead of starting from a common shape, you can do that too:

new Mesh()
    .AddVertex(0f, 0f, 0f, out var v0)
    .AddVertex(1f, 0f, 0f, out var v1)
    .AddVertex(1f, 1f, 0f, out var v2)
    .AddVertex(0f, 1f, 0f, out var v3)
    .AddFace(new[] { v0, v1, v2 }, out var f0)
    .AddFace(new[] { v0, v2, v3 }, out var f1);

This is what the built-in primitives are doing under the hood.

• See Icosahedron.cs
• See QuadCube.cs

Navigating meshes

Once you've built a mesh, you can navigate and modify the mesh easily. Some examples:

myMesh.Faces[0].GetAdjacentFaces();

myMesh.Vertices[0].IncomingHalfEdges;

myMesh.HalfEdges[0].Twin.Face;