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  3. TDynamicMeshOverlay

TDynamicMeshOverlay

[TDynamicMeshOverlay](API\Runtime\GeometryCore\DynamicMesh\TDynamicMeshOverlay) is an add-on to a [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) that allows for per-triangle storage of an "element" (eg like a per-triangle UV or normal).

API > API/Runtime > API/Runtime/GeometryCore > API/Runtime/GeometryCore/DynamicMesh

Inheritance Hierarchy

References

   
Module GeometryCore
Header /Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/DynamicMeshOverlay.h
Include #include "DynamicMesh/DynamicMeshOverlay.h"

Syntax

template<typename RealType, int ElementSize>  
class TDynamicMeshOverlay

Remarks

TDynamicMeshOverlay is an add-on to a FDynamicMesh3 that allows for per-triangle storage of an "element" (eg like a per-triangle UV or normal). However the elements can be shared between triangles at shared vertices because the elements are stored in a separate indexable list.

Each element has one vertex in the parent mesh as its parent, whereas each vertex may be the parent of multiple elements in cases where neighboring triangles are not sharing a single element for that vertex. This means that there may be "seam" boundary edges in the overlay topology that are not mesh boundary edges in the associated/parent mesh, but the overlay topology will not connect triangles that were not connected in the parent mesh or create any topologically degenerate triangles, since the parent vids of the elements of a triangle will have to match up to the vids of the triangle.

A "seam" edge is one where at least one of the elements of the triangles on either side of the edge is not shared between the two triangles.

The FDynamicMesh3 mesh topology operations (eg split/flip/collapse edge, poke face, etc) can be mirrored to the overlay via OnSplitEdge(), etc.

Note that although this is a template, many of the functions are defined in the .cpp file. As a result you need to explicitly instantiate and export the instance of the template that you wish to use in the block at the top of DynamicMeshOverlay.cpp

Variables

  Type Name Description
Protected variable TDynamicVector< RealType > Elements List of element values
Protected variable FRefCountVector ElementsRefCounts Reference counts of element indices. Iterate over this to find out which elements are valid.
Protected variable TDynamicVector< int > ElementTriangles List of triangle element-index triplets [Elem0 Elem1 Elem2]
Protected variable FDynamicMesh3 * ParentMesh The parent mesh this overlay belongs to
Protected variable TDynamicVector< int > ParentVertices List of parent vertex indices, one per element

Constructors

  Type Name Description
Public function   Create an empty overlay
Public function   Create an overlay for the given parent mesh

Functions

  Type Name Description
Public function int

AppendElement ( RealType ConstantValue
)

 Allocate a new element with the given constant value
Public function int

AppendElement ( const RealType* Value
)

 Allocate a new element with the given value
Public function Const bool

AreTrianglesConnected ( int TriangleID0,
int TriangleID1
)

  
Public function void Support for inserting element at specific ID.
Public function Const bool

CheckValidity ( bool bAllowNonManifoldVertices,
EValidityCheckFailMode FailMode
)

 Checks that the overlay mesh is well-formed, ie all internal data structures are consistent
Public function void Discard all elements.
Public function void

ClearElements ( const EnumerableIntType& Triangles
)

 Discard elements for given triangles.
Public function void

CompactCopy ( const FCompactMaps& CompactMaps,
const TDynamicMeshOverlay< RealType, ElementSize >& Copy
)

 Copy the Copy overlay to a compact rep, also updating parent references based on the CompactMaps
Public function void

CompactInPlace ( const FCompactMaps& CompactMaps
)

 Compact overlay and update links to parent based on CompactMaps
Public function void

Copy ( const TDynamicMeshOverlay< RealType, ElementSize >& Copy
)

 Set this overlay to contain the same arrays as the copy overlay
Public function Const int

CountVertexElements ( int VertexID,
bool bBruteForce
)

 Count the number of unique elements for a given parent-mesh vertex
Public function void

CreateFromPredicate ( TFunctionRef< bool(int ParentVertexIdx, int TriIDA, int TriIDB)> TrisCanShareVertexPredicate,
RealType InitElementValue
)

 Build overlay topology from a predicate function, e.g. to build topology for sharp normals
Public function Const int  
Public function Const element_iterator  
Public function void Call after a set of unsafe InsertVertex() calls to rebuild free list
Public function void

FreeUnusedElements ( const TSet< int >* ElementsToCheck
)

 Goes through elements and frees any whose reference counts indicate that they are not being used.
Public function Const void

GetElement ( int ElementID,
AsType& Data
)

 Get the element at a given index
Public function Const void

GetElement ( int ElementID,
RealType* Data
)

 Accessors/QueriesGet the element at a given index
Public function Const void

GetElementAtVertex ( int TriangleID,
int VertexID,
AsType& Data
)

 Get the Element value associated with a vertex of a triangle.
Public function Const int

GetElementIDAtVertex ( int TriangleID,
int VertexID
)

 Find the element ID at a vertex of a triangle.
Public function Const void

GetElementTriangles ( int ElementID,
TArray< int >& OutTriangles
)

 Find the triangles connected to an element
Public function FDynamicMesh3 *  
Public function Const const FDynamicMesh3 *  
Public function Const int

GetParentVertex ( int ElementID
)

 Get the parent vertex id for the element at a given index
Public function Const FIndex3i

GetTriangle ( int TriangleID
)

 Get the element index tuple for a triangle
Public function Const bool

GetTriangleIfValid ( int TriangleID,
FIndex3i& TriangleOut
)

 If the triangle is set to valid element indices, return the indices in TriangleOut and return true, otherwise return false
Public function Const void

GetTriBaryInterpolate ( int32 TriangleID,
const AsType* BaryCoords,
AsType* DataOut
)

 Compute interpolated parameter value inside triangle using barycentric coordinates
Public function Const void

GetVertexElements ( int VertexID,
TArray< int >& OutElements
)

 Find the elements associated with a given parent-mesh vertex
Public function Const bool  
Public function void

InitializeNewTriangle ( int TriangleID
)

 Set a triangle's element indices to InvalidID
Public function void

InitializeTriangles ( int MaxTriangleID
)

 Initialize the triangle list to the given size, and set all triangles to InvalidID
Public function EMeshResult

InsertElement ( int ElementID,
const RealType* Value,
bool bUnsafe
)

 Insert element at given index, assuming it is unused.
Protected function void

InternalSetTriangle ( int TriangleID,
const FIndex3i& TriElements,
bool bUpdateRefCounts,
bool bAllowElementFreeing
)

 Updates the triangles array and optionally the element reference counts
Public function Const bool

IsBowtieInOverlay ( int32 VertexID
)

 Determines whether the base-mesh vertex has "bowtie" topology in the Overlay.
Public function Const bool  
Public function Const bool

IsElement ( int vID
)

  
Public function Const bool

IsSameAs ( const TDynamicMeshOverlay< RealType, ElementSize >& Other,
bool bIgnoreDataLayout
)

 Returns true if this overlay is the same as Other.
Public function Const bool

IsSeamEdge ( int EdgeID,
bool* bIsNonIntersectingOut
)

 Returns true if the parent-mesh edge is a "Seam" in this overlay.
Public function Const bool

IsSeamEndEdge ( int EdgeID
)

 Returns true if the parent-mesh edge is a "Seam End" in this overlay, meaning the adjacent element triangles share one element, not two
Public function Const bool

IsSeamVertex ( int VertexID,
bool bBoundaryIsSeam
)

 Returns true if the parent-mesh vertex is connected to any seam edges
Public function Const bool

IsSetTriangle ( int TID
)

  
Public function Const int  
Public function bool

MergeElement ( int SourceElementID,
int TargetElementID
)

 Collapse SourceElementID into TargetElementID, resulting in connecting any containing triangles and reducing the total elements in the overlay.
Public function void Update the overlay to reflect an edge collapse in the parent mesh
Public function void Update the overlay to reflect an edge flip in the parent mesh
Public function void Update the overlay to reflect an edge merge in the parent mesh
Public function void Update the overlay to reflect a face poke in the parent mesh
Public function void

OnRemoveTriangle ( int TriangleID
)

 Remove a triangle from the overlay
Public function void

OnReverseTriOrientation ( int TriangleID
)

 Reverse the orientation of a triangle's elements
Public function void Update the overlay to reflect an edge split in the parent mesh
Public function void

OnSplitVertex ( const DynamicMeshInfo::FVertexSplitInfo& SplitInfo,
const TArrayView< const int >& TrianglesToUpdate
)

 Update the overlay to reflect a vertex split in the parent mesh
Public function void

Serialize ( FArchive& Ar,
const FCompactMaps* CompactMaps,
bool bUseCompression
)

 Serialize to and from an archive.
Public function void

SetElement ( int ElementID,
const AsType& Data
)

 Set the element at a given index
Public function void

SetElement ( int ElementID,
const RealType* Data
)

 Set the element at a given index
Protected function void

SetElementFromBary ( int SetElement,
int ElementA,
int ElementB,
int ElementC,
const FVector3d& BaryCoords
)

 Set the value at an Element to be a barycentric interpolation of three other Elements
Protected function void

SetElementFromLerp ( int SetElement,
int ElementA,
int ElementB,
double Alpha
)

 Set the value at an Element to be a linear interpolation of two other Elements
Public function void

SetParentVertex ( int ElementIndex,
int ParentVertexIndex
)

  
Public function EMeshResult

SetTriangle ( int TriangleID,
const FIndex3i& TriElements,
bool bAllowElementFreeing
)

 Set the triangle to the given Element index tuple, and increment element reference counts
Public function void Refine an existing overlay topology by splitting any bow ties
Public function void

SplitBowtiesAtVertex ( int32 Vid,
TArray< int32 >* NewElementIDs
)

 Split any bowties at given vertex.
Public function int

SplitElement ( int ElementID,
const TArrayView< const int >& TrianglesToUpdate
)

 Create a new copy of ElementID, and update connected triangles in the TrianglesToUpdate array to reference the copy of ElementID where they used to reference ElementID (Note: This just calls "SplitElementWithNewParent" with the existing element's parent id.)
Public function int

SplitElementWithNewParent ( int ElementID,
int SplitParentVertexID,
const TArrayView< const int >& TrianglesToUpdate
)

 Create a new copy of ElementID, and update connected triangles in the TrianglesToUpdate array to reference the copy of ElementID where they used to reference ElementID.
Public function void

SplitVerticesWithPredicate ( TFunctionRef< bool(int ElementIdx, int TriID)> ShouldSplitOutVertex,
TFunctionRef< void(int ElementIdx, int TriID, RealType*FillVect)> GetNewElementValue
)

 Refine an existing overlay topology.
Public function Const bool

TriangleHasElement ( int TriangleID,
int ElementID
)

  
Public function void

UnsetTriangle ( int TriangleID,
bool bAllowElementFreeing
)

 Set the triangle to have InvalidID element IDs, decrementing element reference counts if needed.

Typedefs

Name Description
element_iterator  

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