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FMeshTriOrderedEdgeID identifies an oriented edge in a triangle mesh based on indices into the triangle vertices. IE if a triangle has vertices [A,B,C], then an oriented edge could be (A,B) or (B,A), or any of the other 4 permutations. So the ordered edge in the triangle can be represented as two vertex indices, and the full encoding is (TriangleID, J, K) where J and K are in range 0/1/2.
This type of edge identifier is applicable on any indexed mesh, even if the mesh does not store explicit edge IDs. In addition, this identifier is stable across mesh topological changes, ie if two connected triangles are unlinked (ie the shared edge becomes two edges, and the 2 vertices become 4), the FMeshTriOrderedEdgeID will still refer to the correct oriented edge, as it does not explicitly depend on the Vertex or Edge IDs, only the ordering within the triangle.
Note that cycling or permuting the vertices of a triangle will change/break these indices.
| Name | FMeshTriOrderedEdgeID |
| Type | struct |
| Header File | /Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/InfoTypes.h |
| Include Path | #include "DynamicMesh/InfoTypes.h" |
Syntax
struct FMeshTriOrderedEdgeID
Constructors
| Name | Remarks | Include Path | Unreal Specifiers |
|---|---|---|---|
| DynamicMesh/InfoTypes.h | |||
FMeshTriOrderedEdgeID
(
int32 TriangleIDIn, |
DynamicMesh/InfoTypes.h |
Variables
Public
| Name | Type | Remarks | Include Path | Unreal Specifiers |
|---|---|---|---|---|
| TriangleID | int32 | The index of the mesh Triangle | DynamicMesh/InfoTypes.h | |
| VertIndexA | unsigned | The 0/1/2 index of the first vertex in the triangles tuple of vertices | DynamicMesh/InfoTypes.h | |
| VertIndexB | unsigned | The 0/1/2 index of the second vertex in the triangles tuple of vertices | DynamicMesh/InfoTypes.h |