142 lines
4.4 KiB
C++
142 lines
4.4 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
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#include "Operations/MeshIsoCurves.h"
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#include "Async/ParallelFor.h"
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#include "DynamicMesh/DynamicMesh3.h"
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#include "Operations/LocalPlanarSimplify.h"
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using namespace UE::Geometry;
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void FMeshIsoCurves::Cut(FDynamicMesh3& Mesh, TFunctionRef<float(int32)> VertexFn, TFunctionRef<float(int32 VIDMin, int32 VIDMax, float ValMin, float ValMax)> EdgeCutFn, float IsoValue)
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{
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int MaxVID = Mesh.MaxVertexID();
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TArray<float> VertexValues;
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VertexValues.SetNumUninitialized(MaxVID);
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constexpr bool bNoParallel = false;
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ParallelFor(MaxVID, [this, &VertexValues, &Mesh, &VertexFn, IsoValue](int32 VID)
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{
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if (Mesh.IsVertex(VID))
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{
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VertexValues[VID] = VertexFn(VID);
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}
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else
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{
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// set IsoValue on invalid vertices; any vertex that is later inserted and uses this ID will be on the curve, so should have this value
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VertexValues[VID] = IsoValue;
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}
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}, bNoParallel);
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TSet<int> OnCutEdges;
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SplitCrossingEdges(Mesh, VertexValues, OnCutEdges, EdgeCutFn, IsoValue);
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// collapse degenerate edges
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if (Settings.bCollapseDegenerateEdgesOnCut)
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{
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FLocalPlanarSimplify::CollapseDegenerateEdges(Mesh, OnCutEdges, false, Settings.DegenerateEdgeTol);
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}
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}
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void FMeshIsoCurves::SplitCrossingEdges(FDynamicMesh3& Mesh, const TArray<float>& VertexValues,
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TSet<int32>& OnCutEdges,
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TFunctionRef<float(int32 VIDMin, int32 VIDMax, float ValMin, float ValMax)> EdgeCutFn,
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float IsoValue)
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{
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OnCutEdges.Reset();
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// have to skip processing of new edges. If edge id
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// is > max at start, is new. Otherwise if in NewEdges list, also new.
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int MaxEID = Mesh.MaxEdgeID();
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TSet<int> NewEdgesBeforeMaxID;
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auto AddNewEdge = [&NewEdgesBeforeMaxID, MaxEID](int32 NewEID)
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{
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if (NewEID < MaxEID)
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{
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NewEdgesBeforeMaxID.Add(NewEID);
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}
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};
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double UseSnapVertTol = FMath::Max(0, Settings.SnapToExistingVertexTol);
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const double SnapExistingTolSq = UseSnapVertTol * UseSnapVertTol;
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// split existing edges where the value crosses isovalue
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for (int32 EID = 0; EID < MaxEID; ++EID)
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{
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if (!Mesh.IsEdge(EID) || NewEdgesBeforeMaxID.Contains(EID))
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{
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continue;
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}
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FIndex2i EdgeV = Mesh.GetEdgeV(EID);
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const float ValueA = VertexValues[EdgeV.A];
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const float ValueB = VertexValues[EdgeV.B];
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const float DistA = ValueA - IsoValue;
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const float DistB = ValueB - IsoValue;
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// If both Signs are 0, this edge is on-contour
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// If one sign is 0, that vertex is on-contour
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int AOnCurve = (FMathd::Abs(DistA) <= Settings.CurveIsoValueSnapTolerance) ? 1 : 0;
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int BOnCurve = (FMathd::Abs(DistB) <= Settings.CurveIsoValueSnapTolerance) ? 1 : 0;
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if (AOnCurve || BOnCurve)
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{
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continue;
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}
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// no crossing
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if (DistA * DistB >= 0)
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{
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continue;
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}
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double Param = EdgeCutFn(EdgeV.A, EdgeV.B, ValueA, ValueB);
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// Cut must be within edge
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if (Param <= 0 || Param >= 1)
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{
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continue;
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}
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// Skip the edge split if we're within tolerance of an existing vertex
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if (SnapExistingTolSq > 0)
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{
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FVector3d PosA = Mesh.GetVertex(EdgeV.A);
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FVector3d PosB = Mesh.GetVertex(EdgeV.B);
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FVector3d EdgeVec = PosB - PosA;
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double MinSepSq = (EdgeVec * (Param > .5 ? 1 - Param : Param)).SquaredLength();
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if (MinSepSq <= SnapExistingTolSq)
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{
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continue;
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}
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}
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FDynamicMesh3::FEdgeSplitInfo SplitInfo;
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EMeshResult SplitResult = Mesh.SplitEdge(EID, SplitInfo, Param);
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if (!ensureMsgf(SplitResult == EMeshResult::Ok, TEXT("FMeshIsoCurves::SplitCrossingEdges: failed to SplitEdge")))
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{
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continue; // edge split really shouldn't fail; skip the edge if it somehow does
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}
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AddNewEdge(SplitInfo.NewEdges.A);
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AddNewEdge(SplitInfo.NewEdges.B);
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// We need to check whether the other vertices are on curve to decide if the connected edges are on the curve or not
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int32 OtherVIDA = SplitInfo.OtherVertices.A;
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// Other vertex is on curve if it's newly created or within curve isovalue tolerance
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// (Note a newly-created vertex w/ ID < VertexValues.Num() will also have a VertexValue of IsoValue, since we use this as the default value)
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if (OtherVIDA >= VertexValues.Num() || FMath::Abs(VertexValues[OtherVIDA] - IsoValue) <= Settings.CurveIsoValueSnapTolerance)
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{
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OnCutEdges.Add(SplitInfo.NewEdges.B);
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}
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if (SplitInfo.NewEdges.C != FDynamicMesh3::InvalidID)
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{
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AddNewEdge(SplitInfo.NewEdges.C);
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int32 OtherVIDB = SplitInfo.OtherVertices.B;
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if (OtherVIDB >= VertexValues.Num() || FMath::Abs(VertexValues[OtherVIDB] - IsoValue) <= Settings.CurveIsoValueSnapTolerance)
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{
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OnCutEdges.Add(SplitInfo.NewEdges.C);
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}
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}
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}
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}
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