GeometryCollectionToDynamicMesh.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
 
#include "GeometryBase.h"
 
PREDECLARE_GEOMETRY(class FDynamicMesh3);
struct FManagedArrayCollection;
class FGeometryCollection;
 
namespace UE::Geometry
{
 
struct FGeometryCollectionToDynamicMeshes
{
    struct FMeshInfo
    {
        // Transform Index of the bone represented
        int32 TransformIndex = -1;
        // Mesh holding the geometry at (or under) a given bone, in a common coordinate space
        TUniquePtr<FDynamicMesh3> Mesh;
        // Stores the Transform that has *already* been applied to the Mesh vertices, which took it from local bone space to a common space
        FTransform Transform = FTransform::Identity;
    };
 
    TArray<FMeshInfo> Meshes;
 
 
    
    enum class EInvisibleFaceConversion : uint8
    {
        Skip,
        TagWithPolygroup
    };
 
    struct FToMeshOptions
    {
        FTransform Transform = FTransform::Identity;
 
        bool bWeldVertices = false;
        bool bSaveIsolatedVertices = false;
 
        bool bInternalFaceTagsAsPolygroups = true;
        EInvisibleFaceConversion InvisibleFaces = EInvisibleFaceConversion::Skip;
    };
 
    struct FToCollectionOptions
    {
        // Whether to set faces with no 'visible' tag as visible (if true) or invisible (if false)
        bool bDefaultFaceVisible = true;
        // Whether to set faces with no 'internal' tag as internal (if true) or external (if false)
        bool bDefaultFaceInternal = false;
        // Whether the appended geometry is allowed to be added as a root transform (if NewMeshParentIndex == -1)
        bool bAllowAppendAsRoot = false;
 
        // Parent index to use if adding a new mesh (with no existing transform) -- if invalid, will add to root
        int32 NewMeshParentIndex = -1;
    };
 
    // Convert all meshes in the given collection to dynamic meshes
    MESHCONVERSIONENGINETYPES_API bool Init(const FManagedArrayCollection& Collection, const FToMeshOptions& Options);
 
    // Convert the meshes in the collection at the given transforms to dynamic meshes
    MESHCONVERSIONENGINETYPES_API bool InitFromTransformSelection(const FManagedArrayCollection& Collection, TConstArrayView<int32> TransformIndices, const FToMeshOptions& Options);
 
    // Update a geometry collection with the current meshes array
    // Note this updates a Geometry Collection rather than the more general FManagedArrayCollection because some of the updating code is specific to geometry collection
    MESHCONVERSIONENGINETYPES_API bool UpdateGeometryCollection(FGeometryCollection& Collection, const FToCollectionOptions& Options) const;
 
    // Add a new mesh to the geometry collection
    // Note this updates a Geometry Collection rather than the more general FManagedArrayCollection because some of the updating code is specific to geometry collection
    // @return Index of added transform
    MESHCONVERSIONENGINETYPES_API static int32 AppendMeshToCollection(FGeometryCollection& Collection, const FDynamicMesh3& Mesh, const FTransform& MeshTransform, const FToCollectionOptions& Options);
 
 
 
    // Get the name used for the polygroup that we optionally set on the dynamic mesh, corresponding to the internal face tags of the geometry collection triangles
    static MESHCONVERSIONENGINETYPES_API FName InternalFacePolyGroupName();
    // Get the name used for the polygroup that we optionally set on the dynamic mesh, corresponding to the invisible face tags of the geometry collection triangles
    static MESHCONVERSIONENGINETYPES_API FName VisibleFacePolyGroupName();
 
private:
    
    // private helper method with shared implementation for all Init* methods
    // @param bTransformInComponentSpace If false, the Transforms array holds transforms that are relative to the corresponding bone parent. If true, the Transforms are all relative to a common coordinate space.
    bool InitHelper(const FManagedArrayCollection& Collection, bool bTransformInComponentSpace, TConstArrayView<FTransform3f> Transforms, bool bAllTransforms, TConstArrayView<int32> TransformIndices, const FToMeshOptions& Options);
    static TConstArrayView<FTransform3f> GetCollectionTransforms(const FManagedArrayCollection& Collection);
 
    // Update an existing geometry in a collection w/ a new mesh (w/ the same number of faces and vertices!)
    static bool UpdateCollection(const FTransform& FromCollection, const FDynamicMesh3& Mesh, int32 GeometryIdx, FGeometryCollection& Output, const FToCollectionOptions& Options);
};
 
} // namespace UE::Geometry::GeometryCollectionDynamicMeshConversion