void TriangleMesh::buildAdjacency()
{
int nPruned = pruneInvalidFaces( m_edgeToFace );
int nFaces = numFaces();
// walk over all faces
// and build an adjacency map:
// edge -> adjacent face
// if nothing was pruned, then it's already valid
if( nPruned != 0 )
{
m_edgeToFace.clear();
for( int f = 0; f < nFaces; ++f )
{
Vector3i face = m_faces[ f ];
Vector2i e0 = face.xy;
Vector2i e1 = face.yz;
Vector2i e2 = face.zx();
m_edgeToFace[ e0 ] = f;
m_edgeToFace[ e1 ] = f;
m_edgeToFace[ e2 ] = f;
}
}
// build face to face adjacency
// for each face:
// find 3 edges
// flip edge: if the flipped edge has an adjacent face
// add it as a neighbor of this face
m_faceToFace.clear();
m_faceToFace.resize( nFaces );
for( int f = 0; f < nFaces; ++f )
{
Vector3i face = m_faces[ f ];
// get 3 edge twins
Vector2i e0t = face.yx();
Vector2i e1t = face.zy();
Vector2i e2t = face.xz();
if( m_edgeToFace.find( e0t ) != m_edgeToFace.end() )
{
m_faceToFace[ f ].push_back( m_edgeToFace[ e0t ] );
}
if( m_edgeToFace.find( e1t ) != m_edgeToFace.end() )
{
m_faceToFace[ f ].push_back( m_edgeToFace[ e1t ] );
}
if( m_edgeToFace.find( e2t ) != m_edgeToFace.end() )
{
m_faceToFace[ f ].push_back( m_edgeToFace[ e2t ] );
}
}
// build edge to next edge adjacency
// iterate over all faces
m_edgeToPrevEdge.clear();
m_edgeToNextEdge.clear();
for( int f = 0; f < nFaces; ++f )
{
Vector3i face = m_faces[ f ];
Vector2i e0 = face.xy;
Vector2i e1 = face.yz;
Vector2i e2 = face.zx();
m_edgeToPrevEdge[ e0 ] = e2;
m_edgeToPrevEdge[ e1 ] = e0;
m_edgeToPrevEdge[ e2 ] = e1;
m_edgeToNextEdge[ e0 ] = e1;
m_edgeToNextEdge[ e1 ] = e2;
m_edgeToNextEdge[ e2 ] = e0;
}
// build vertex to outgoing edge adjacency
int nVertices = numVertices();
m_vertexToOutgoingEdge.clear();
m_vertexToOutgoingEdge.resize( nVertices );
for( int f = 0; f < nFaces; ++f )
{
Vector3i face = m_faces[ f ];
m_vertexToOutgoingEdge[ face[0] ] = face[ 1 ];
m_vertexToOutgoingEdge[ face[1] ] = face[ 2 ];
m_vertexToOutgoingEdge[ face[2] ] = face[ 0 ];
}
// build vertex to vertex (one-ring neighborhoods)
// for each vertex v
// start with initial outgoing edge
// next edge = edge->next->next->twin
m_oneRingIsClosed.clear();
m_vertexToVertex.clear();
m_vertexToFace.clear();
m_oneRingIsClosed.resize( nVertices );
m_vertexToVertex.resize( nVertices );
m_vertexToFace.resize( nVertices );
for( int v = 0; v < nVertices; ++v )
{
Vector2i initialOutgoingEdge{ v, m_vertexToOutgoingEdge[ v ] };
m_vertexToVertex[ v ].push_back( initialOutgoingEdge.y );
m_vertexToFace[ v ].push_back( m_edgeToFace[ initialOutgoingEdge ] );
Vector2i nextIncomingEdge = m_edgeToNextEdge[ m_edgeToNextEdge[ initialOutgoingEdge ] ];
Vector2i nextOutgoingEdge = nextIncomingEdge.yx();
while( !( isBoundaryEdge( nextIncomingEdge ) ) &&
nextOutgoingEdge != initialOutgoingEdge )
{
m_vertexToVertex[ v ].push_back( nextIncomingEdge.x );
m_vertexToFace[ v ].push_back( m_edgeToFace[ nextOutgoingEdge ] );
nextIncomingEdge = m_edgeToNextEdge[ m_edgeToNextEdge[ nextOutgoingEdge ] ];
nextOutgoingEdge = nextIncomingEdge.yx();
}
// if we looped around, great, we're done
// otherwise, we hit a boundary, need to go the other way around!
if( isBoundaryEdge( nextIncomingEdge ) )
{
m_oneRingIsClosed[ v ] = false;
// don't forget to push on the last vertex
m_vertexToVertex[ v ].push_back( nextIncomingEdge.x );
// no face
// check that the initial outgoing edge is not a boundary
// (otherwise we're done)
if( isBoundaryEdge( initialOutgoingEdge ) )
{
continue;
}
// flip orientation: start from the initial outgoing edge
// and go clockwise, pushing to the front
Vector2i initialIncomingEdge = initialOutgoingEdge.yx();
nextOutgoingEdge = m_edgeToNextEdge[ initialIncomingEdge ];
nextIncomingEdge = nextOutgoingEdge.yx();
while( !( isBoundaryEdge( nextOutgoingEdge ) ) )
{
m_vertexToVertex[ v ].push_front( nextOutgoingEdge.y );
m_vertexToFace[ v ].push_front( m_edgeToFace[ nextOutgoingEdge ] );
nextOutgoingEdge = m_edgeToNextEdge[ nextIncomingEdge ];
nextIncomingEdge = nextOutgoingEdge.yx();
}
// don't forget the last vertex
m_vertexToVertex[ v ].push_front( nextOutgoingEdge.y );
m_vertexToFace[ v ].push_front( m_edgeToFace[ nextOutgoingEdge ] );
}
else
{
m_oneRingIsClosed[ v ] = true;
}
}
}
int TriangleMesh::pruneInvalidFaces( std::map< Vector2i, int >& edgeToFace )
{
// walk over all faces
// build for each edge (v0,v1)
// edgeToFace[ v0, v1 ] = face
// if it already exists, we have a problem
// and we will throw the face away
int nFaces = numFaces();
edgeToFace.clear();
//edgeToFace.reserve( 3 * nFaces );
std::vector< Vector3i > validFaces;
validFaces.reserve( nFaces );
//ProgressReporter pr( "Pruning invalid faces", nFaces );
int nPruned = 0;
for( int f = 0; f < nFaces; ++f )
{
Vector3i face = m_faces[ f ];
Vector2i e0 = face.xy;
Vector2i e1 = face.yz;
Vector2i e2 = face.zx();
if( edgeToFace.find( e0 ) == edgeToFace.end() &&
edgeToFace.find( e1 ) == edgeToFace.end() &&
edgeToFace.find( e2 ) == edgeToFace.end() )
{
edgeToFace[ e0 ] = f;
edgeToFace[ e1 ] = f;
edgeToFace[ e2 ] = f;
validFaces.push_back( face );
}
else
{
++nPruned;
fprintf( stderr, "Found invalid face: (%d, %d, %d)\n",
face.x, face.y, face.z );
if( edgeToFace.find( e0 ) != edgeToFace.end() )
{
Vector3i existingFace = m_faces[ edgeToFace[ e0 ] ];
fprintf( stderr, "Existing face: (%d, %d, %d)\n",
existingFace.x, existingFace.y, existingFace.z );
}
if( edgeToFace.find( e1 ) != edgeToFace.end() )
{
Vector3i existingFace = m_faces[ edgeToFace[ e1 ] ];
fprintf( stderr, "Existing face: (%d, %d, %d)\n",
existingFace.x, existingFace.y, existingFace.z );
}
if( edgeToFace.find( e2 ) != edgeToFace.end() )
{
Vector3i existingFace = m_faces[ edgeToFace[ e2 ] ];
fprintf( stderr, "Existing face: (%d, %d, %d)\n",
existingFace.x, existingFace.y, existingFace.z );
}
}
//pr.notifyAndPrintProgressString();
}
if( nPruned > 0 )
{
fprintf( stderr, "Pruned %d faces\n", nPruned );
m_faces = validFaces;
}
return nPruned;
}