Enum TopologyError 

pub enum TopologyError {
    BadTriangle(u32),
    BadAdjacentTrianglesOrientation {
        triangle1: u32,
        triangle2: u32,
        edge: (u32, u32),
    },
}

Errors that occur when computing or validating triangle mesh topology.

Triangle mesh topology describes the connectivity and adjacency relationships between vertices, edges, and triangles. When constructing a mesh with TriMeshFlags::HALF_EDGE_TOPOLOGY, Parry validates these relationships and returns this error if inconsistencies are found.

When This Occurs

Topology errors typically occur when:

• The mesh is non-manifold (edges with more than 2 adjacent faces)
• Adjacent triangles have inconsistent winding order
• Triangles have degenerate geometry (duplicate vertices)

Variants

BadTriangle(u32)

A triangle has two or three identical vertices (degenerate triangle).

This error indicates that a triangle in the mesh references the same vertex multiple times, creating a degenerate triangle (zero area). For example, a triangle with indices [5, 5, 7] or [1, 2, 1].

Degenerate triangles cannot be part of a valid mesh topology because they don’t have proper edges or face normals.

Alternatively, use TriMeshFlags::DELETE_DEGENERATE_TRIANGLES to automatically remove degenerate triangles:

let flags = TriMeshFlags::HALF_EDGE_TOPOLOGY
    | TriMeshFlags::DELETE_BAD_TOPOLOGY_TRIANGLES;

let mesh = TriMesh::with_flags(vertices, indices, flags)
    .expect("Bad triangles removed");

BadAdjacentTrianglesOrientation

Two adjacent triangles have opposite orientations (inconsistent winding).

For a manifold mesh with consistent normals, adjacent triangles must have compatible orientations. If two triangles share an edge, they must traverse that edge in opposite directions.

This error reports:

• triangle1, triangle2: The indices of the two conflicting triangles
• edge: The shared edge as a pair of vertex indices (v1, v2)

Example of the Problem

CORRECT (opposite winding on shared edge):
  Triangle 1: [a, b, c]  ->  edge (a,b)
  Triangle 2: [b, a, d]  ->  edge (b,a)  ✓ opposite direction

INCORRECT (same winding on shared edge):
  Triangle 1: [a, b, c]  ->  edge (a,b)
  Triangle 2: [a, b, d]  ->  edge (a,b)  ✗ same direction!

Common Causes

• Mixing clockwise and counter-clockwise triangle definitions
• Incorrectly constructed mesh from modeling software
• Manual mesh construction with inconsistent winding
• Merging separate meshes with different conventions

Fields

triangle1: u32

The first triangle, with an orientation opposite to the second triangle.

triangle2: u32

The second triangle, with an orientation opposite to the first triangle.

edge: (u32, u32)

The edge shared between the two triangles.

Trait Implementations

impl Clone for TopologyError

fn clone(&self) -> TopologyError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for TopologyError

impl Debug for TopologyError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for TopologyError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for TopologyError

impl Error for TopologyError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for TopologyError

fn eq(&self, other: &TopologyError) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for TopologyError