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  3. FMeshSimpleShapeApproximation

FMeshSimpleShapeApproximation

[FMeshSimpleShapeApproximation](API\Plugins\DynamicMesh\FMeshSimpleShapeApproximation) can calculate various "simple" shape approximations for a set of meshes, by fitting various primitives/hulls/etc to each mesh.

API > API/Plugins > API/Plugins/DynamicMesh

FMeshSimpleShapeApproximation can calculate various "simple" shape approximations for a set of meshes, by fitting various primitives/hulls/etc to each mesh. The assumption is that the input mesh(es) are already partitioned into pieces.

There are various Generate_X() functions which apply different strategies, generally to fit a containing simple shape or hull to the mesh. However in addition to these explicit strategies, input meshes that are very close to approximations of spheres/boxes/capsules (ie basically meshed versions of these primitives) can be identified and used directly, skipping the fitting process.

   
Name FMeshSimpleShapeApproximation
Type class
Header File /Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/ShapeApproximation/MeshSimpleShapeApproximation.h
Include Path #include "ShapeApproximation/MeshSimpleShapeApproximation.h"

Syntax

class FMeshSimpleShapeApproximation

Structs

Name Remarks
FSourceMeshCache  

Enums

Public

Name Remarks
EProjectedHullAxisMode Type/Mode for deciding 3D axis to use in Generate_ProjectedHulls()

Variables

Public

Name Type Remarks Include Path Unreal Specifiers
bConvexDecompositionProtectNegativeSpace bool Whether to use 'navigation-driven' convex decomposition using NegativeSpaceTolerance and NegativeSpaceMinRadius to define space that the decomposition hulls cannot occupy ShapeApproximation/MeshSimpleShapeApproximation.h  
bDecompositionPreSimplifyWithEdgeLength bool Whether to use apply an edge-length based simplification to the input before running convex decompositions. ShapeApproximation/MeshSimpleShapeApproximation.h  
bDetectBoxes bool Should boxes be auto-detected ShapeApproximation/MeshSimpleShapeApproximation.h  
bDetectCapsules bool Should capsules be auto-detected ShapeApproximation/MeshSimpleShapeApproximation.h  
bDetectConvexes bool Should convex be auto-detected ShapeApproximation/MeshSimpleShapeApproximation.h  
bDetectSpheres bool Configuration parameters Should spheres be auto-detected ShapeApproximation/MeshSimpleShapeApproximation.h  
bIgnoreInternalNegativeSpace bool Whether to ignore negative space that is not accessible by traversing from the convex hull (via paths w/ radius of at least Negative Space Tolerance) ShapeApproximation/MeshSimpleShapeApproximation.h  
bSimplifyHulls bool Should hulls be simplified as a post-process ShapeApproximation/MeshSimpleShapeApproximation.h  
bUseConvexDecompositionMaxPieces bool Whether to use the above Max Pieces to drive the convex decomposition. ShapeApproximation/MeshSimpleShapeApproximation.h  
bUseExactComputationForBox bool   ShapeApproximation/MeshSimpleShapeApproximation.h  
ConvexDecompositionErrorTolerance double Error tolerance to guide convex decomposition (in cm); we stop adding new parts if the volume error is below the threshold. ShapeApproximation/MeshSimpleShapeApproximation.h  
ConvexDecompositionMaxPieces int32 How many convex pieces to target per mesh when creating convex decompositions. ShapeApproximation/MeshSimpleShapeApproximation.h  
ConvexDecompositionMinPartThickness double Minimum part thickness for convex decomposition (in cm); hulls thinner than this will be merged into adjacent hulls, if possible. ShapeApproximation/MeshSimpleShapeApproximation.h  
ConvexDecompositionSearchFactor float How much additional decomposition decomposition + merging to do, as a fraction of max pieces. ShapeApproximation/MeshSimpleShapeApproximation.h  
DecompositionPreSimplifyEdgeLength double If enabled by the above bool flag, pre-simplify input geometry to this edge length before computing convex decompositions. ShapeApproximation/MeshSimpleShapeApproximation.h  
HullSimplifyTolerance double Simplification tolerance when simplifying 2D convex hulls, eg for swept/projected hulls ShapeApproximation/MeshSimpleShapeApproximation.h  
HullTargetFaceCount int32 Target number of triangles when simplifying 3D convex hulls ShapeApproximation/MeshSimpleShapeApproximation.h  
LevelSetGridResolution int32 Level Set Grid resolution along longest axis ShapeApproximation/MeshSimpleShapeApproximation.h  
MinDimension double Minimal dimension of fit shapes, eg thickness/radius/etc (currently only enforced in certain cases) ShapeApproximation/MeshSimpleShapeApproximation.h  
NegativeSpaceMinRadius double Minimum radius of negative space to protect; tunnels with radius smaller than this could be filled in ShapeApproximation/MeshSimpleShapeApproximation.h  
NegativeSpaceTolerance double Negative space closer to the input than this tolerance distance can be filled in ShapeApproximation/MeshSimpleShapeApproximation.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

void Generate_AlignedBoxes ( FSimpleShapeSet3d& ShapeSetOut
)

 Approximation generators Fit containing axis-aligned boxes to each input mesh and store in ShapeSetOut ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_Capsules ( FSimpleShapeSet3d& ShapeSetOut
)

 Fit containing approximate-minimum-volume capsules to each input mesh and store in ShapeSetOut ShapeApproximation/MeshSimpleShapeApproximation.h  
Calculate multiple 3D Convex Hulls for each input mesh and store in ShapeSetOut. ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_ConvexHulls ( FSimpleShapeSet3d& ShapeSetOut,
FProgressCancel* Progress
)

 Calculate 3D Convex Hulls for each input mesh and store in ShapeSetOut. ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_LevelSets ( FSimpleShapeSet3d& ShapeSetOut,
FProgressCancel* Progress
)

   ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_MinimalSpheres ( FSimpleShapeSet3d& ShapeSetOut
)

 Fit containing minimal-volume spheres to each input mesh and store in ShapeSetOut ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_MinVolume ( FSimpleShapeSet3d& ShapeSetOut
)

 Fit containing axis-aligned box, oriented box, capsule, and sphere to each input mesh, and store the one with smallest volume in ShapeSetOut ShapeApproximation/MeshSimpleShapeApproximation.h  

void Generate_OrientedBoxes ( FSimpleShapeSet3d& ShapeSetOut,
FProgressCancel* Progress
)

 Fit containing minimal-volume oriented boxes to each input mesh and store in ShapeSetOut ShapeApproximation/MeshSimpleShapeApproximation.h  
Calculate Projected Convex Hulls for each input mesh and store in ShapeSetOut. ShapeApproximation/MeshSimpleShapeApproximation.h  

void InitializeSourceMeshes ( const TArray< const FDynamicMesh3* >& InputMeshSet
)

 Setup/initialization Initialize internal mesh sets. ShapeApproximation/MeshSimpleShapeApproximation.h  

Protected

Name Remarks Include Path Unreal Specifiers

void DetectAndCacheSimpleShapeType ( const FDynamicMesh3* SourceMesh,
FSourceMeshCache& CacheOut
)

   ShapeApproximation/MeshSimpleShapeApproximation.h  

bool GetDetectedSimpleShape ( const FSourceMeshCache& Cache,
FSimpleShapeSet3d& ShapeSetOut,
FCriticalSection& ShapeSetLock
)

   ShapeApproximation/MeshSimpleShapeApproximation.h  

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