GenerateAdjacencyAndPointReps

DirectXMesh

Generates the adjacency and/or point representatives for a mesh.

HRESULT GenerateAdjacencyAndPointReps(
   const uint16_t* indices, size_t nFaces,
   const XMFLOAT3* positions, size_t nVerts,
   float epsilon,
   uint32_t* pointRep, uint32_t* adjacency );

HRESULT GenerateAdjacencyAndPointReps(
   const uint32_t* indices, size_t nFaces,
   const XMFLOAT3* positions, size_t nVerts,
   float epsilon,
   uint32_t* pointRep, uint32_t* adjacency );

Parameters

epsilon: Threshold used when comparing positions for shared/duplicate positions for geometric adjacency. This value can be 0 for bit-wise identical vertex positions, which results in topological adjacency.

If pointRep is nullptr, it is still generated as part of the computation but is not returned to the caller.

If both pointRep and adjacency are nullptr, these functions return an error code.

Remarks

These functions assume the triangular mesh description is valid. See Validate

Example

This computes a topological adjacency:

auto mesh = std::make_unique<WaveFrontReader<uint16_t>>();

if ( FAILED( mesh->Load( L"test.obj" ) ) )
   // Error

size_t nFaces = mesh->indices.size() / 3;
size_t nVerts = mesh->vertices.size();

auto pos = std::make_unique<XMFLOAT3[]>(nVerts);
for( size_t j = 0; j < nVerts; ++j )
   pos[ j ] = mesh->vertices[ j ].position;

auto adj = std::make_unique<uint32_t[]>(mesh->indices.size());
if ( FAILED ( GenerateAdjacencyAndPointReps(
   mesh->indices.data(), nFaces,
   pos.get(), nVerts, 0.f, nullptr, adj.get() ) ) )
   // Error

Changing the last statement to use a non-zero epsilon returns a geometric adjacency:

if ( FAILED ( GenerateAdjacencyAndPointReps(
   mesh->indices.data(), nFaces,
   pos.get(), nVerts, 1e-5f, nullptr, adj.get() ) ) )
   // Error