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FConvexDecomposition3

API > API/Runtime > API/Runtime/GeometryCore > API/Runtime/GeometryCore/CompGeom

References

   
Module GeometryCore
Header /Engine/Source/Runtime/GeometryCore/Public/CompGeom/ConvexDecomposition3.h
Include #include "CompGeom/ConvexDecomposition3.h"

Syntax

class FConvexDecomposition3

Variables

  Type Name Description
Public variable double BiasToRemoveTooThinParts A bias term to favor merging away 'too thin' parts before merging other parts, expressed as a volume in units s.t.
Public variable double ConnectedComponentTolerance Threshold for considering two components to be touching.
Public variable double ConvexEdgeAngleMoreSamplesThreshold Angle at edge above which we take 5 sample planes instead of 3, to better cover the wider range (expressed in degrees)
Public variable double ConvexEdgeAngleThreshold Angle at edge above which we don't sample it as a convex edge (expressed in degrees)
Public variable double CutLargestAxisErrorScale Scale factor for error on the largest axis; slightly favoring cutting on the largest axis helps get more consistent result when no initial cut will reduce error (e.g. a torus)
Public variable TIndirectArray< FConvexPart > Decomposition All convex hulls parts in the convex decomposition Note this must be an indirect array, not a TArray, because FConvexPart holds an FDynamicMesh3 mesh, which is not trivially movable
Public variable TMultiMap< int32, int32 > DecompositionToProximity Mapping from Decomposition indices to Proximity indices.
Public variable int32 MaxConvexEdgePlanes Maximum number of convex edges to sample for possible cutting planes when calling SplitWorst() to generate an initial convex decomposition Larger values will cost more to run but can let the algorithm find a cleaner decomposition
Public variable double OnPlaneTolerance Maximum 'on plane' distance for points during planar cuts.
Public variable TArray< FProximity > Proximities All potential merge edges between Decomposition FConvexParts.
Public variable double ProximityTolerance Threshold for considering two convex parts close enough to consider merging.
Public variable FTransformSRT3d ResultTransform Transform taking the result hull vertices back to the original space of the inputs; automatically applied by GetVertices()

Constructors

  Type Name Description
Public function    
Public function  

FConvexDecomposition3 ( const FDynamicMesh3& SourceMesh,
bool bMergeEdges
)

  

Functions

  Type Name Description
Public function void

Compact ()

 Compact the decomposition representation to the minimal needed for output: Just the hull vertices and triangles, no internal geometry This will prevent some further processing on the representation; to ensure it is called only when the geometry is no longer needed, instead of calling this directly, call MergeBest with bAllowCompact=true
Public function void

Compute ( int32 NumOutputHulls,
int32 NumAdditionalSplits,
double ErrorTolerance,
double MinThicknessTolerance,
int32 MaxOutputHulls
)

 Compute a decomposition with the desired number of hulls Note: A future version of this function may replace NumOutputHulls with MaxOutputHulls, but this version keeps both parameters for compatibility / consistent behavior.
Public function Const double

ConvertDistanceToleranceToLocalSpace ( double DistTolerance
)

 Simple helper to convert an error tolerance expressed in world space to local space
Public function Const double Simple helper to convert an error tolerance expressed in world space to a local-space volume tolerance
Public function void

DeleteProximity ( int32 ProxIdx,
bool bDeleteMapReferences
)

 Helper function to delete a proximity relationship, and fix index references to account for the new array ordering
Public function Const FDynamicMesh3

GetHullMesh ( int32 HullIdx
)

  
Public function Const const FDynamicMesh3 &

GetInternalMesh ( int32 HullIdx
)

 Get the non-hull geometry underlying a part of the convex decomposition.
Public function Const TArray< FIndex3i > const &

GetTriangles ( int32 HullIdx
)

  
Public function Const TArray< TVector< RealType > >

GetVertices ( int32 HullIdx,
bool bTransformedToOutput
)

  
Public function void

InitializeFromHulls ( int32 NumHulls,
TFunctionRef< double(int32)> HullVolumes,
TFunctionRef< int32(int32)> HullNumVertices,
TFunctionRef< FVector3d(int32, int32)> HullVertices,
TArrayView< const TPair< int32, int32 >> Proximity
)

 Initialize from convex hulls allows the caller to only use the hull merging phase of the algorithm
Public function void

InitializeFromIndexMesh ( TArrayView< const FVector3f > Vertices,
TArrayView< const FIntVector > Faces,
bool bMergeEdges,
int32 FaceVertexOffset
)

 Initialize convex decomposition with a triangle index mesh
Public function void

InitializeFromMesh ( const FDynamicMesh3& SourceMesh,
bool bMergeEdges
)

  
Public function int32

MergeBest ( int32 TargetNumParts,
double ErrorTolerance,
double MinThicknessTolerance,
bool bAllowCompact,
bool bRequireHullTriangles,
int MaxOutputHulls,
const FSphereCovering* OptionalNegativeSpace,
const FTransform* OptionalTransformIntoNegativeSpace
)

 Merge the pairs of convex hulls in the decomposition that will least increase the error.
Public function Const int32 Results
Public function int32

SplitWorst ( bool bCanSkipUnreliableGeoVolumes,
double ErrorTolerance
)

 Split the worst convex part, and return the increase in the total number of convex parts after splitting (can be more than 1 if result has multiple separate connected components) Note: could return 0 if no splits were possible
Public function void

UpdateProximitiesAfterSplit ( int32 SplitIdx,
int32 NewIdxStart,
FPlane3d CutPlane,
int32 SecondSideIdxStart,
double OrigHullVolume
)

 Helper function to update all proximity data after splitting an FConvexPart apart

Classes

  Type Name Description
Public struct FConvexPart Representation of a convex hull in the decomposition + associated information to help further split or merge.  
Public struct FProximity Edge in a graph of merge candidates, indicating which Decomposition parts could be merged together Note a proximity link does not guarantee that the geometry (or convex hulls) are touching  

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