vertex_normals

iskra.geometry.normals.vertex_normals(verts: Tensor, faces: Tensor, method: Literal['default', 'graph', 'area', 'angle'] = 'default') → Tensor[SOURCE]

Comptues per-vertex normals.

Normals are computed per face and then reduced to the vertices using a a weighted average. The weighting is determined via the argument method. The function works for triangle meshes in 3D and polylines in 2D.

Parameters:

• verts (Tensor[Float, [V, 2 | 3]]) – Mesh vertex positions.

• faces (Tensor[Int, [F, 2 | 3]]) – Mesh face indices.

• method (Literal["default", "graph", "area", "angle"]) –

  Normal averaging method. One of:

  • `default`: selects angle weighing for triangle meshes and area

    weighing for polyline meshes. Chosen by default.

  • `area`: weighs each face normal by that face’s hypervolume,

    approximating an integrated normal vector.

  • `angle`: angle-based normal vectors based on the heuristic from

    [TODO: cite]. By far the most visually pleasent, but only work on 3D meshes and a bit less theoretically justified than others.

  • `graph`: each face normal gets weight 1.0.

Raises:

• ValueError – Passing method=angle for a polyline mesh with raise an error.

• ValueError – method must be in ["default", "graph", "area", "angle"]`.

• NotImplementedError – Simplices must have either 2 or 3 corners.

Returns:

​ (Tensor[Float, [V, 2 | 3]]) – Vertex-based normals