88 lines
2.4 KiB
C++
88 lines
2.4 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
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#pragma once
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#include "MathUtil.h"
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#include "VectorTypes.h"
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#include "GeometryTypes.h"
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#include "Polygon2.h"
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#include "DynamicMesh/DynamicMesh3.h"
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#define UE_API DYNAMICMESH_API
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namespace UE
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{
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namespace Geometry
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{
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/**
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* Calculate a Convex Hull for a Mesh by first Projecting all vertices to a plane, computing a
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* 2D convex polygon that contains them, and then sweeping that 2D hull to create an extruded 3D volume.
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*/
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class FMeshProjectionHull
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{
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public:
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/** Input Mesh */
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const FDynamicMesh3* Mesh;
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/** Input 3D Frame/Plane */
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FFrame3d ProjectionFrame;
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/** If true, 2D convex hull is simplified using MinEdgeLength and DeviationTolerance */
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bool bSimplifyPolygon = false;
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/** Minimum Edge Length of the simplified 2D Convex Hull */
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double MinEdgeLength = 0.01;
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/** Deviation Tolerance of the simplified 2D Convex Hull */
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double DeviationTolerance = 0.1;
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/** Minimum thickness of extrusion. If extrusion length is smaller than this amount, box is expanded symmetrically */
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double MinThickness = 0.0;
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/** Calculated convex hull polygon */
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FPolygon2d ConvexHull2D;
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/** Simplified convex hull polygon. Not initialized if bSimplifyPolygon == false */
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FPolygon2d SimplifiedHull2D;
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/** Output swept-polygon convex hull */
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FDynamicMesh3 ConvexHull3D;
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enum class EKeep3DHullSide : uint8
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{
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// Both sides of the projection hull will be flat
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None,
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// The front of the projection hull will follow the 3D convex hull, and the back will be flat
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Front,
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// The back of the projection hull will follow the 3D convex hull, and the front will be flat
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Back
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// Note: If both the front and back follow the 3D hull, that is just a regular convex hull; see MeshConvexHull.h
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};
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/** Whether to conform to the 3D convex hull surface on the front or back side of the sweep, or to use a flat surface on both sides of the swept hull */
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EKeep3DHullSide Keep3DHullSide = EKeep3DHullSide::None;
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public:
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FMeshProjectionHull(const FDynamicMesh3* MeshIn)
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{
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Mesh = MeshIn;
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}
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/**
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* Calculate output 2D Convex Polygon and Swept-Polygon 3D Mesh for vertices of input Mesh
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* @return true on success
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*/
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UE_API bool Compute();
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private:
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// Helper to compute the 3D hull when Keep3DHullSide is not None; called by Compute after the 2D projection hull is computed
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UE_API bool ComputeWith3DHullSide(FFrame3d CenterFrame, double ExtrudeLength);
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};
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} // end namespace UE::Geometry
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} // end namespace UE
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#undef UE_API
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