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105 lines
3.3 KiB
C++
105 lines
3.3 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
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#include "ConversionUtils/VolumeToDynamicMesh.h"
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#include "CompGeom/PolygonTriangulation.h"
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#include "DynamicMesh3.h"
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#include "GameFramework/Volume.h"
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#include "MeshBoundaryLoops.h"
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#include "MeshQueries.h"
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#include "MeshRegionBoundaryLoops.h"
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#include "Model.h"
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#include "Operations/MergeCoincidentMeshEdges.h"
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#include "Operations/MinimalHoleFiller.h"
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#include "Operations/PlanarFlipsOptimization.h"
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#include "ExplicitUseGeometryMathTypes.h" // using UE::Geometry::(math types)
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using namespace UE::Geometry;
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namespace UE {
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namespace Conversion {
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void VolumeToDynamicMesh(AVolume* Volume, FDynamicMesh3& Mesh,
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const FVolumeToMeshOptions& Options)
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{
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Mesh.DiscardAttributes();
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if (Options.bSetGroups)
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{
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Mesh.EnableTriangleGroups();
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}
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UModel* Model = Volume->Brush;
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UE::Geometry::FTransform3d XForm = (Options.bInWorldSpace) ?
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UE::Geometry::FTransform3d(Volume->GetTransform()) : UE::Geometry::FTransform3d::Identity();
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// Each "BspNode" is a planar polygon, triangulate each polygon and accumulate in a mesh.
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// Note that this does not make any attempt to weld vertices/edges
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for (const FBspNode& Node : Model->Nodes)
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{
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FVector3d Normal = (FVector3d)Node.Plane;
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FFrame3d Plane(Node.Plane.W * Normal, Normal);
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int32 NumVerts = (Node.NodeFlags & PF_TwoSided) ? Node.NumVertices / 2 : Node.NumVertices; // ??
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if (NumVerts > 0)
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{
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TArray<int32> VertIndices;
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TArray<FVector2d> VertPositions2d;
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VertIndices.SetNum(NumVerts);
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VertPositions2d.SetNum(NumVerts);
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for (int32 VertexIndex = 0; VertexIndex < NumVerts; ++VertexIndex)
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{
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const FVert& Vert = Model->Verts[Node.iVertPool + VertexIndex];
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FVector3d Point = (FVector3d)Model->Points[Vert.pVertex];
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Point = XForm.TransformPosition(Point);
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VertIndices[VertexIndex] = Mesh.AppendVertex(Point);
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VertPositions2d[VertexIndex] = Plane.ToPlaneUV(Point, 2);
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}
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TArray<FIndex3i> PolyTriangles;
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PolygonTriangulation::TriangulateSimplePolygon(VertPositions2d, PolyTriangles);
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int32 GroupID = FDynamicMesh3::InvalidID;
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if (Options.bSetGroups)
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{
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GroupID = Mesh.AllocateTriangleGroup();
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}
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for (FIndex3i Tri : PolyTriangles)
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{
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// flip orientation here...
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Mesh.AppendTriangle(VertIndices[Tri.A], VertIndices[Tri.C], VertIndices[Tri.B], GroupID);
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}
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}
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}
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if (Options.bMergeVertices)
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{
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// Merge the mesh edges to create a closed solid
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double MinLen, MaxLen, AvgLen;
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TMeshQueries<FDynamicMesh3>::EdgeLengthStats(Mesh, MinLen, MaxLen, AvgLen);
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FMergeCoincidentMeshEdges Merge(&Mesh);
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Merge.MergeVertexTolerance = FMathd::Max(Merge.MergeVertexTolerance, MinLen * 0.1);
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Merge.Apply();
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// If the mesh is not closed, the merge failed or the volume had cracks/holes.
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// Do trivial hole fills to ensure the output is solid (really want autorepair here)
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if (Mesh.IsClosed() == false && Options.bAutoRepairMesh)
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{
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FMeshBoundaryLoops BoundaryLoops(&Mesh, true);
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for (FEdgeLoop& Loop : BoundaryLoops.Loops)
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{
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FMinimalHoleFiller Filler(&Mesh, Loop);
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Filler.Fill();
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}
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}
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// try to flip towards better triangles in planar areas, should reduce/remove degenerate geo
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if (Options.bOptimizeMesh)
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{
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FPlanarFlipsOptimization(&Mesh, 5).Apply(); // Do five passes
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}
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}
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}
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}}//end namespace UE::Conversion
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