MeshIndexUtil.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/Set.h"
#include "DynamicMesh/DynamicMesh3.h"
#include "DynamicMesh/DynamicMeshOverlay.h"
#include "HAL/Platform.h"
#include "IndexTypes.h"
#include "Misc/AssertionMacros.h"
 
namespace UE
{
namespace Geometry
{
    GEOMETRYCORE_API void TriangleToVertexIDs(const FDynamicMesh3* Mesh, TConstArrayView<int> TriangleIDs, TArray<int>& VertexIDsOut);
 
 
    GEOMETRYCORE_API void VertexToTriangleOneRing(const FDynamicMesh3* Mesh, TConstArrayView<int> VertexIDs, TSet<int>& TriangleIDsOut);
 
 
    template<typename OverlayType, typename EnumeratorType, typename OutputSetType>
    void TrianglesToOverlayElements(const OverlayType* Overlay, EnumeratorType TriangleEnumeration, OutputSetType& ElementsOut);
 
 
 
    GEOMETRYCORE_API FIndex2i FindVertexEdgesInTriangle(const FDynamicMesh3& Mesh, int32 TriangleID, int32 VertexID);
 
 
    GEOMETRYCORE_API int32 FindSharedEdgeInTriangles(const FDynamicMesh3& Mesh, int32 Triangle0, int32 Triangle1);
 
 
    template<typename EnumeratorType, typename SetType>
    void CollectVertexPositions(const FDynamicMesh3& Mesh, EnumeratorType Enumeration, SetType& Output);
 
 
    template<typename TrisConnectedPredicate>
    FIndex3i FindNextAdjacentTriangleAroundVtx(const FDynamicMesh3* Mesh,
        int32 VertexID, int32 FromTriangleID, int32 PrevTriangleID,
        TrisConnectedPredicate TrisConnectedTest);
 
    GEOMETRYCORE_API bool SplitBoundaryVertexTrianglesIntoSubsets(
        const FDynamicMesh3* Mesh,
        int32 VertexID,
        int32 SplitEdgeID,
        TArray<int32>& TriangleSet0, TArray<int32>& TriangleSet1);
 
    GEOMETRYCORE_API bool SplitInteriorVertexTrianglesIntoSubsets(
        const FDynamicMesh3* Mesh,
        int32 VertexID,
        int32 SplitEdgeID0, int32 SplitEdgeID1,
        TArray<int32>& TriangleSet0, TArray<int32>& TriangleSet1);
 
}
}
 
 
 
// implementations of functions declared above
 
namespace UE
{
namespace Geometry
{
 
template<typename EnumeratorType, typename SetType>
void CollectVertexPositions(const FDynamicMesh3& Mesh, EnumeratorType Enumeration, SetType& Output)
{
    for (int32 vid : Enumeration)
    {
        if (Mesh.IsVertex(vid))
        {
            Output.Add(Mesh.GetVertex(vid));
        }
    }
}
 
 
template<typename TrisConnectedPredicate>
FIndex3i FindNextAdjacentTriangleAroundVtx(const FDynamicMesh3* Mesh, 
    int32 VertexID, int32 FromTriangleID, int32 PrevTriangleID,
    TrisConnectedPredicate TrisConnectedTest)
{
    check(Mesh);
 
    // find neigbour edges and tris for triangle
    FIndex3i TriEdges = Mesh->GetTriEdges(FromTriangleID);
    FIndex3i TriNbrTris;
    for (int32 j = 0; j < 3; ++j)
    {
        FIndex2i EdgeT = Mesh->GetEdgeT(TriEdges[j]);
        TriNbrTris[j] = (EdgeT.A == FromTriangleID) ? EdgeT.B : EdgeT.A;
    }
 
    // Search for the neighbour tri that is not PrevTriangleID, and is also connected to VertexID.
    // This is our next triangle around the ring
    for (int32 j = 0; j < 3; ++j)
    {
        if (TriNbrTris[j] != PrevTriangleID && Mesh->IsTriangle(TriNbrTris[j]))
        {
            FIndex3i TriVerts = Mesh->GetTriangle(TriNbrTris[j]);
            if (TriVerts.A == VertexID || TriVerts.B == VertexID || TriVerts.C == VertexID)
            {
                // test if predicate allows this connection
                if (TrisConnectedTest(FromTriangleID, TriNbrTris[j], TriEdges[j]) == false)
                {
                    break;
                }
                return FIndex3i(TriNbrTris[j], TriEdges[j], j);
            }
        }
    }
 
    return FIndex3i(IndexConstants::InvalidID, IndexConstants::InvalidID, IndexConstants::InvalidID);
}
 
 
 
template<typename OverlayType, typename EnumeratorType, typename OutputSetType>
void TrianglesToOverlayElements(const OverlayType* Overlay, EnumeratorType TriangleEnumeration, OutputSetType& ElementsOut)
{
    for (int32 TriangleID : TriangleEnumeration)
    {
        if ( Overlay->IsSetTriangle(TriangleID) )
        {
            FIndex3i TriElements = Overlay->GetTriangle(TriangleID);
            ElementsOut.Add(TriElements.A);
            ElementsOut.Add(TriElements.B);
            ElementsOut.Add(TriElements.C);
        }
    }
}
 
 
 
}
}