GT_OSD3.h

Go to the documentation of this file.

/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        GT_OSD3.h (GT Library, C++)
 *
 * COMMENTS:
 */

#ifndef __GT_OSD3__
#define __GT_OSD3__

#if defined(WIN32)
    // MSVC does not provide readable alternatives to operators by default
    // (i.e. && => 'and') so we have to include this header since OpenSubdiv
    // makes use of some of the alternatives such as 'not', 'and' and 'or'.
    #include <iso646.h>
#endif

#include "GT_API.h"
#include "GT_Types.h"
#include "GT_PrimPolygonMesh.h"
#include <SYS/SYS_Hash.h>
#include <UT/UT_UniquePtr.h>
#include <opensubdiv/far/ptexIndices.h>
#include <opensubdiv/far/primvarRefiner.h>
#include <opensubdiv/far/patchTableFactory.h>
#include <opensubdiv/far/patchMap.h>
#include <opensubdiv/far/stencilTable.h>
#include <opensubdiv/far/stencilTableFactory.h>
#include <opensubdiv/bfr/surface.h>

class UT_JSONWriter;

/// @file
/// This file contains code to support OpenSubdiv 3.x for the GT library
/// The code in here is primarily used in GT_UtilOpenSubdiv

/// Options for topology and refinement
class GT_API GT_OSDOptions
{
public:
    using SdcOptions = OpenSubdiv::Sdc::Options;
    using VtxBoundaryInterpolation = SdcOptions::VtxBoundaryInterpolation;
    using FVarLinearInterpolation = SdcOptions::FVarLinearInterpolation;
    using CreasingMethod = SdcOptions::CreasingMethod;
    using TriangleSubdivision = SdcOptions::TriangleSubdivision;

    GT_OSDOptions(GT_Scheme scheme = GT_CATMULL_CLARK,
                int level = 2,
                bool adaptive = false,
                fpreal crease_override = -1,
                bool remove_holes = true)
        : myOptions()
        , myScheme(scheme)
        , myCreaseOverride(crease_override)
        , myLevel(level)
        , myAdaptive(adaptive)
        , myRemoveHoles(remove_holes)
    {
        // Set default behaviour
        setVtxBoundaryInterpolation(SdcOptions::VTX_BOUNDARY_EDGE_AND_CORNER);
        setFVarLinearInterpolation(SdcOptions::FVAR_LINEAR_BOUNDARIES);
    }

    const SdcOptions    &options() const { return myOptions; }
    void                 setOptions(const SdcOptions &o) { myOptions = o; }

    SYS_HashType        hash() const;
    bool                isEqual(const GT_OSDOptions &opts) const;
    bool                operator==(const GT_OSDOptions &s) const
                            { return isEqual(s); }
    bool                operator!=(const GT_OSDOptions &s) const
                            { return !isEqual(s); }

    // Access this object as it were an OpenSubdiv::Sdc::Options
    SdcOptions          &operator->() { return myOptions; }
    const SdcOptions    &operator->() const { return myOptions; }
    SdcOptions          &operator*() { return myOptions; }
    const SdcOptions    &operator*() const { return myOptions; }

    GT_Scheme   scheme() const { return myScheme; }
    void        setScheme(GT_Scheme t) { myScheme = t; }

    int         level() const { return myLevel; }
    void        setLevel(int l) { myLevel = l; }

    bool        adaptive() const { return myAdaptive; }
    void        setAdaptive(bool b) { myAdaptive = b; }

    bool        removeHoles() const { return myRemoveHoles; }
    void        setRemoveHoles(bool v) { myRemoveHoles = v; }

    bool        enableCreaseOverride() const { return myCreaseOverride >= 0; }
    fpreal      creaseOverride() const  { return myCreaseOverride; }
    void        setCreaseOverride(fpreal value=-1) { myCreaseOverride = value; }

#define GETSET(TYPE, GET) \
    TYPE        GET() const { return myOptions.Get##TYPE(); } \
    void        set##TYPE(TYPE v) { myOptions.Set##TYPE(v); }

    /// @{
    /// Simple wrappers on the SdcOptions
    GETSET(VtxBoundaryInterpolation, vtxBoundaryInterpolation);
    GETSET(FVarLinearInterpolation, fvarLinearInterpolation);
    GETSET(CreasingMethod, creasingMethod);
    GETSET(TriangleSubdivision, triangleSubdivision);
    /// @}
#undef GETSET

    void        dump() const;
    void        dump(UT_JSONWriter &w) const;

private:
    SdcOptions  myOptions;
    GT_Scheme   myScheme;
    fpreal      myCreaseOverride;
    int         myLevel;
    bool        myAdaptive;
    bool        myRemoveHoles;
};

/// Options for setting up limit surface evaluation.
class GT_API GT_OSDPatchTableOptions
{
public:
    using FactoryOptions = OpenSubdiv::Far::PatchTableFactory::Options;

    GT_OSDPatchTableOptions()
        : myOptions()
    {
    }

    bool        isEqual(const GT_OSDPatchTableOptions &o) const;
    bool        operator==(const GT_OSDPatchTableOptions &o) const
                    { return isEqual(o); }
    bool        operator!=(const GT_OSDPatchTableOptions &o) const
                    { return !isEqual(o); }
    void        dump() const;
    void        dump(UT_JSONWriter &w) const;

    FactoryOptions              &operator*() { return myOptions; }
    const FactoryOptions        &operator*() const { return myOptions; }

    FactoryOptions::EndCapType  endCapType() const
                    { return (FactoryOptions::EndCapType)myOptions.endCapType; }
    bool        generateAllLevels() const
                    { return myOptions.generateAllLevels; }
    bool        triangulateQuads() const
                    { return myOptions.triangulateQuads; }
    bool        useSingleCreasePatch() const
                    { return myOptions.useSingleCreasePatch; }
    int         maxIsolationLevel() const
                    { return myOptions.maxIsolationLevel; }
    bool        shareEndCapPatchPoints() const
                    { return myOptions.shareEndCapPatchPoints; }
    bool        generateFVarTables() const
                    { return myOptions.generateFVarTables; }
    int         numFVarChannels() const
                    { return myOptions.numFVarChannels; }
    const int   *fvarChannelIndices() const
                    { return myOptions.fvarChannelIndices; }

    void        setEndCapType(FactoryOptions::EndCapType t)
                    { myOptions.endCapType = (FactoryOptions::EndCapType)t; }
    void        setGenerateAllLevels(bool v)
                    { myOptions.generateAllLevels = v; }
    void        setTriangulateQuads(bool v)
                    { myOptions.triangulateQuads = v; }
    void        setUseSingleCreasePatch(bool v)
                    { myOptions.useSingleCreasePatch = v; }
    void        setMaxIsolationLevel(int v)
                    { myOptions.maxIsolationLevel = v; }
    void        setShareEndCapPatchPoints(bool v)
                    { myOptions.shareEndCapPatchPoints = v; }
    void        setGenerateFVarTables(bool v)
                    { myOptions.generateFVarTables = v; }
    void        setNumFVarChannels(int n)
                    { myOptions.numFVarChannels = n; }
    void        setFVarChannelIndices(const int *indices)
                    { myOptions.fvarChannelIndices = indices; }
    void        setLegacyLinearPatches(bool b)
                    { myOptions.generateFVarLegacyLinearPatches = b; }
private:
    FactoryOptions      myOptions;
};

/// Topology definition for opensubdiv classes
class GT_API GT_OSDTopology
{
public:
    using TopologyRefiner = OpenSubdiv::Far::TopologyRefiner;
    using LevelInfo = OpenSubdiv::Far::TopologyLevel;

     GT_OSDTopology();
    ~GT_OSDTopology();

    /// @{
    /// Debug - dump the topology out
    void        dump() const;
    void        dump(UT_JSONWriter &w) const;
    /// @}

    bool        isEqual(const GT_OSDTopology &src) const;
    bool        operator==(const GT_OSDTopology &o) const { return isEqual(o); }

    static SYS_HashType hash(const GT_PrimPolygonMesh &mesh,
                                const GT_OSDOptions &options);
    static SYS_HashType areEqual(const GT_PrimPolygonMesh &a,
                                const GT_PrimPolygonMesh &b);

    /// Create the topology for the given polygonal hull and options.  Note
    /// that if the mesh is a GT_PrimSubdivisionMesh, crease weights will be
    /// picked up from the tags on the primitive.
    bool        create(const GT_PrimPolygonMesh &mesh,
                        const GT_OSDOptions &options);

    /// Number of levels in refinement (note this is the max level + 1)
    exint               levelCount() const
                            { return myRefiner->GetNumLevels(); }

    /// Access to the level information for a given refinement level
    /// This returns the number of vertices, face-varying vertices, faces, etc.
    /// for each level.  Level 0 is the "coarse" mesh.
    /// - GetNumVertices() - Number of shared points (i.e. Houdini points)
    /// - GetNumFaces() - Number of faces
    /// - GetNumEdges() - Number of edges
    /// - GetNumFaceVertices() - Number of face varying (i.e. Houdini vertices)
    const LevelInfo     &levelInfo(int level) const
                            { return myRefiner->GetLevel(level); }
    const LevelInfo     &lastLevel() const
                            { return levelInfo(myRefiner->GetNumLevels()-1); }


    /// @{
    /// Return specific information about the coarse mesh (i.e. level 0)
    GT_Size     coarseFaceCount() const
                    { return levelInfo(0).GetNumFaces(); }
    GT_Size     coarsePointCount() const
                    { return levelInfo(0).GetNumVertices(); }
    GT_Size     coarseVertexCount() const
                    { return levelInfo(0).GetNumFaceVertices(); }
    GT_Size     coarseVertexCount(GT_Size face_index) const;
    /// @}

    /// Access to the refiner
    const TopologyRefiner       *refiner() const { return myRefiner; }

    /// Test whether this has been built for adaptive refinement
    bool                adaptive() const { return myAdaptive; }

    /// Create a polygon mesh for a given level
    GT_PrimitiveHandle  createMesh(int level,
                                const GT_AttributeListHandle &point,
                                const GT_AttributeListHandle &vertex,
                                const GT_AttributeListHandle &uniform,
                                const GT_AttributeListHandle &detail,
                                const GT_FaceSetMapPtr &fsets=GT_FaceSetMapPtr()) const;

    /// Build and return ptex to faceid mapping
    UT_IntArray         ptexToFaceMap() const;

private:
    TopologyRefiner            *myRefiner;
    bool                        myAdaptive;
    bool                        myRemoveHoles;
};

// Interface to create and look through a stencil table
class GT_API GT_OSDStencilTable
{
public:
    using TopologyRefiner = OpenSubdiv::Far::TopologyRefiner;
    using StencilTable = OpenSubdiv::Far::StencilTable;
    using StencilTableFactory = OpenSubdiv::Far::StencilTableFactory;
    using Stencil = OpenSubdiv::Far::Stencil;

    GT_OSDStencilTable();

    bool create(
            const GT_OSDTopology &topology,
            bool adaptive = false,
            uint interpolate_mode = 0,
            int max_level = -1 /*-1 means use topology's max level*/);

    // Essential getters for GPU buffer creation
    int getNumStencils() const;
    int getNumControlVertices() const;

    // Raw data access for GPU upload
    const int *getSizes() const;
    const int *getOffsets() const;
    const int *getIndices() const;
    const float *getWeights() const;

    bool isInitialized() const { return myTable != nullptr; }
    const StencilTable *getTable() const { return myTable.get(); }

private:
    UT_UniquePtr<const StencilTable> myTable;
    int myMaxLevel = -1;
};

// Interface to create and look through a patch table
class GT_API GT_OSDPatchTable
{
public:
    using TopologyRefiner = OpenSubdiv::Far::TopologyRefiner;
    using PatchTable = OpenSubdiv::Far::PatchTable;
    using PatchTableFactory = OpenSubdiv::Far::PatchTableFactory;
    using PatchDescriptor = OpenSubdiv::Far::PatchDescriptor;
    using ConstIndexArray = OpenSubdiv::Far::ConstIndexArray;
    using PatchParam = OpenSubdiv::Far::PatchParam;
    using PatchType = OpenSubdiv::Far::PatchDescriptor::Type;
    using PtexIndices = OpenSubdiv::Far::PtexIndices;
    using Handle = PatchTable::PatchHandle;

    GT_OSDPatchTable();

    bool create(const GT_OSDTopology &top,
                bool createPtexMap=false,
                bool legacy_linear=true,
                ConstIndexArray selectedfaces=ConstIndexArray());

    bool        isEqual(const GT_OSDPatchTable &p) const;
    bool        operator==(const GT_OSDPatchTable &o) const
                        { return isEqual(o); }
    void        dump() const;
    void        dump(UT_JSONWriter &w )const;

    // Array level queries
    int arrayCount() const;
    int arrayPatchCount(int arr) const;
    int numLocalPoints() const;
    int numLocalPointsVarying() const;
    ConstIndexArray vertexArray(int arr) const;
    ConstIndexArray varyingVertexArray(int arr) const;
    PatchDescriptor arrayPatchDesc(int arr) const;
    template<typename T>
    void computeLocalPoints(const T *src, T *dest) const
    {
        if (myTable)
            myTable->ComputeLocalPointValues(src, dest);
    }
    template<typename T>
    void computeLocalFVPoints(const T *src, T *dest) const
    {
        if (myTable)
            myTable->ComputeLocalPointValuesFaceVarying(src, dest);
    }

    // Patch level queries
    PatchParam patchParam(int arr, int pat) const;
    ConstIndexArray patchVertices(const Handle &patch) const;
    ConstIndexArray patchFVValues(const Handle &patch) const;
    void evaluateBasis(const Handle &patch, float u, float v,
                       float *w, float *du, float *dv) const;
    void evaluateBasis(const Handle &patch, float u, float v,
                       float *w, float *du, float *dv,
                       float *duu, float *duv, float *dvv) const;
    void evaluateBasisFV(const Handle &patch, float u, float v,
                       float *w, float *du, float *dv) const;
    void evaluateBasisFV(const Handle &patch, float u, float v,
                       float *w, float *du, float *dv,
                       float *duu, float *duv, float *dvv) const;
    // For ptex queries
    int numPtexFaces() const;
    const int *getPtexMap() const { return myPtexMap.array(); };
    const UT_Array<int> &getPtexArray() const { return myPtexMap; };

    PatchTable *getTable() const { return myTable.get(); };
    bool initialized() const { return myTable != nullptr; };

private:
    UT_UniquePtr<PatchTable> myTable;
    GT_OSDPatchTableOptions  myOptions;
    UT_Array<int>            myPtexMap;
};

/// Storage arrays for vertex data for opensubdiv classes
class GT_API GT_OSDAttributes
{
public:
    /// Identifier for an attribute.  The first item is the index in the
    /// attribute list, the second is whether it's a vertex or a point
    /// attribute.
    using AttribId = std::pair<int, bool>;

    GT_OSDAttributes();
    ~GT_OSDAttributes();

    void        dump() const;
    void        dump(UT_JSONWriter &w )const;

    exint       getMemoryUsage() const;

    bool        create(const GT_OSDTopology &topology,
                       const GT_PrimPolygonMesh &mesh,
                       const GT_OSDPatchTable *table=nullptr);

    bool        update(const GT_OSDTopology &topology,
                       const GT_PrimPolygonMesh &mesh,
                       bool skip_equality_check = false);

    /// Extract a subdivided mesh for the given topology level
    GT_PrimitiveHandle  extractMesh(const GT_OSDTopology &topology,
                                bool harden,
                                int level = -1);

    /// Extract the shared/point attributes for a mesh at the given refinement
    /// level.  If @c harden is @c false, the attributes lists will point to
    /// the temporary buffers (which are over-sized).  Passing @c true to @c
    /// harden will copy out the temporary data into compact arrays.
    GT_AttributeListHandle      extractShared(const GT_OSDTopology &top,
                                        int level_index,
                                        bool harden) const;
    /// Extract the vertex/face-varying attributes for a mesh at the given
    /// refinement level.  See @c extractShared for help on @c harden
    GT_AttributeListHandle      extractVertex(const GT_OSDTopology &top,
                                        int level_index,
                                        bool harden) const;
    /// Extract the primitive/face attributes for a mesh at the given
    /// refinement level.
    GT_AttributeListHandle      extractUniform(const GT_OSDTopology &top,
                                        int level_index,
                                        bool harden) const;

    /// Extract a face map set for a mesh at the given refinement level
    GT_FaceSetMapPtr            extractFaceSets(const GT_OSDTopology &top,
                                        int level_index) const;

    /// Extract a mapping from fine faces at a given refinement level to
    /// its corresponding coarse face
    GT_DataArrayHandle          extractFaceMap(const GT_OSDTopology &top,
                                               int level_index) const;

    /// @{
    /// Find an attribute
    AttribId    findAttribute(const char *name) const;
    AttribId    findAttribute(const char *name, bool vertex_attrib) const;
    /// @}

    /// Return the size of a given attribute
    int         tupleSize(const AttribId &attrib) const;

    /// Extract attributes on the coarse mesh
    bool        coarseValues(const AttribId &attrib,
                        const GT_Size *vertices,
                        GT_Size nvtx,
                        UT_Vector2 *values,
                        int seg) const;

    class GT_API VertexStorage
    {
    public:
        VertexStorage()
            : myAttribs(nullptr)
            , myArrays(nullptr)
            , mySizes(nullptr)
            , myStorage(nullptr)
            , myPointers(nullptr)
            , mySize(0)
            , myReadOnly(true)
        {
        }
        ~VertexStorage()
        {
            clear();
        }

        exint   getMemoryUsage() const;

        int     findAttrib(const char *name) const
        {
            return myAttribs ? myAttribs->getIndex(name) : -1;
        }

        void    init(const GT_AttributeListHandle &list, GT_Size size);
        bool    update(const GT_AttributeListHandle &list,
                       bool skip_equality_check = false);

        void    clear()
        {
            mySize = 0;
            delete [] myArrays;
            delete [] myStorage;
            delete [] myPointers;
            delete [] mySizes;
            myArrays = nullptr;
            myStorage = nullptr;
            myPointers = nullptr;
            mySizes = nullptr;
        }

        /// Extract the attributes for a given level.  Note that the array
        /// returned makes reference to the arrays including the temporary
        /// vertices.  Passing @c harden==true will cause the arrays to be
        /// duplicated (more memory, but more compact)
        GT_AttributeListHandle  extractLevel(const GT_OSDTopology &topology,
                                        int level,
                                        bool harden,
                                        bool fvar) const;

        /// Raw access to the attributes
        const GT_AttributeListHandle    &attribList() const { return myAttribs;}

        /// Access a specific data array in the attributes
        const GT_DataArrayHandle        &attribArray(int attrib) const
                                            { return myAttribs->get(attrib); }

        exint           size() const { return mySize; }
        bool            readOnly() const { return myReadOnly; }
        GT_Size         attribSize(int attrib) const { return mySizes[attrib]; }
        bool            attribValid(int attrib) const
                            { return myPointers[attrib] != nullptr; }
        GT_Storage      attribStorage(int attrib) const
                            { return myStorage[attrib]; }
        GT_Type         attribType(int attrib) const
                            { return myType[attrib]; }
        int             motionSegments() const { return mySegments; }

        template <typename T>
        T       *attribData(int attrib, GT_Size index, int seg)
        {
            UT_ASSERT(myPointers[attrib + mySize * seg]);
            UT_ASSERT(!myReadOnly);
            // Here, we cast away the const, but we know that this is not
            // read-only
            auto data = (T *)myPointers[attrib + mySize * seg];
            return data + index*mySizes[attrib];
        }
        template <typename T>
        const T *attribData(int attrib, GT_Size index, int seg) const
        {
            UT_ASSERT(myPointers[attrib + mySize * seg]);
            auto data = (const T *)myPointers[attrib + mySize * seg];
            return data + index*mySizes[attrib];
        }
        void    dump() const;
        void    dump(UT_JSONWriter &w) const;
    private:
        GT_AttributeListHandle    myAttribs;
        GT_DataArrayHandle       *myArrays;
        GT_Size                  *mySizes;
        GT_Storage               *myStorage;
        GT_Type                  *myType;
        const void              **myPointers;
        GT_Size                   mySize;
        int                       mySegments;
        bool                      myReadOnly;
    };

    class GT_API Vertex
    {
    public:
        Vertex()
            : myStorage(nullptr)
            , myIndex(-1)
            , myMaxWeight(0)
        {
        }
        void    init(VertexStorage &storage, GT_Size index)
        {
            myStorage = &storage;
            myIndex = index;
            myMaxWeight = 0;
        }

        /// Methods required for OpenSubdiv
        const VertexStorage     *storage() const { return myStorage; }
        GT_Size                  index() const { return myIndex; }

        template <typename T>
        const T *attribData(int attrib, int seg) const
        {
            // Make sure to call the const method on myStorage
            return static_cast<const VertexStorage *>(myStorage)->attribData<T>(
                attrib, myIndex, seg);
        }

        // TODO: Templatize?
        void    extract(int attrib_idx, fpreal32 *data, int size,
                        int seg) const;

        void    Clear();
        void    AddWithWeight(const Vertex &src, float weight);
        void    dump() const;
        void    dump(UT_JSONWriter &w) const;
    private:
        VertexStorage   *myStorage;
        GT_Size          myIndex;
        float            myMaxWeight;
    };

    const VertexStorage         &coarseVertex() const
                                    { return myCoarseStorage; }
    const VertexStorage         &coarseFaceVarying() const
                                    { return myCoarseFVStorage; }

    const UT_Array<Vertex>      &vertexArray() const
                                    { return myVertices; }

    const UT_Array<Vertex>      &facevaryingArray() const
                                    { return myFVertices; }

#if 0
    /// Given a face on the coarse mesh, a u/v coordinate from an attribute,
    /// look up the corresponding patch and interpolant.  If the attribute is
    /// invalid, the uv's will be assumed to be the face interpolants using the
    /// scheme where (0,0) maps to the first vertex, (1,0) maps to nvtx-1, (0,
    /// 1) maps to vertex 2, (1,1) maps to nvtx-2 and the remaining vertices
    /// are fit linearly between (0, 1) and (1,1).
    bool        lookupPatch(const GT_OSDTopology &topology,
                    GT_Size coarse_id, fpreal coarse_u, fpreal coarse_v,
                    GT_Size &patch_id, fpreal &patch_u, fpreal &patch_v,
                    const AttribId &attrib) const;

    /// Inverse of @c lookupPatch.  Given a patch, lookup the coarse id and
    /// interpolants.
    bool        lookupFace(GT_Size patch_id, fpreal patch_u, fpreal patch_v,
                    GT_Size &coarse_id, fpreal &coarse_u, fpreal &coarse_v,
                    const AttribId &attrib) const;
#endif

    const VertexStorage &coarseStorage() const { return myCoarseStorage; }
    const VertexStorage &fineStorage() const { return myFineStorage; }
    const VertexStorage &coarseFVStorage() const { return myCoarseFVStorage; }
    const VertexStorage &fineFVStorage() const { return myFineFVStorage; }

    /// Return a pointer to the index-th entry in the given attribute array.
    /// If the index exceeds or equals the number of coarse vertices
    /// (myFineOffset), then the data is located in the fine attribute
    /// array. The first element of the fine attribute array has index
    /// equal to myFineOffset, so we do pointer arithmetic to shift the
    /// array by myFineOffset entries.
    template <typename T>
    const T *getData(int attrib, int index, int seg) const
    {
        if (index < myFineOffset)
        {
            return myCoarseStorage.attribData<T>(attrib, index, seg);
        }
        else
        {
            int offset = index - myFineOffset;
            return myFineStorage.attribData<T>(attrib, offset, seg);
        }
    }

    /// Same idea as with getData, but with face varying data
    template <typename T>
    const T *getDataFV(int attrib, int index, int seg) const
    {
        if (index < myFineFVOffset)
        {
            return myCoarseFVStorage.attribData<T>(attrib, index, seg);
        }
        else
        {
            int offset = index - myFineFVOffset;
            return myFineFVStorage.attribData<T>(attrib, offset, seg);
        }
    }

    int fineOffset() const { return myFineOffset; }
    int fineFVOffset() const { return myFineFVOffset; }

private:
    // Perform interpolation
    void                interpolateData(const GT_OSDTopology &topology);

    GT_AttributeListHandle      myUniform;
    GT_AttributeListHandle      myDetail;
    GT_FaceSetMapPtr            myFaceSets;
    VertexStorage               myCoarseStorage;
    VertexStorage               myFineStorage;
    VertexStorage               myCoarseFVStorage; // Face vertex coarse storage
    VertexStorage               myFineFVStorage; // Face vertex refined storage
    UT_Array<Vertex>            myVertices;
    UT_Array<Vertex>            myFVertices; // Face vertices
    exint                       myFineOffset;
    exint                       myFineFVOffset;
};

/// Minimal interface to Bfr (base-face representation)
class GT_API GT_OSDBfrSurfaces
{
public:
    using Surface = OpenSubdiv::Bfr::Surface<fpreal32>;

    GT_OSDBfrSurfaces(const GT_OSDTopology &topology);
    ~GT_OSDBfrSurfaces();

    /// Minimum. The actual usage may be far greater.
    exint   getMemoryUsage() const;

    /// @{
    /// Calculate patch points for all surfaces to pass to evaluate functions.
    /// Input attrdata must be of float type. Returns GT_DANumeric of same
    /// type. It's up to the caller to store and manage the returned data for
    /// reuse. May return nullptr if invalid (eg surfaces don't exist or the
    /// input attrdata is unsupported type)
    GT_DataArrayHandle  preparePatchPoints(
                            const GT_DataArrayHandle &attrdata) const
    {
        return doPreparePatchPoints<false>(attrdata);
    }

    GT_DataArrayHandle  preparePatchPointsFV(
                            const GT_DataArrayHandle &attrdata) const
    {
        return doPreparePatchPoints<true>(attrdata);
    }
    /// @}

    /// @{
    /// Evaluate attribute and its derivs at specified coordinate.
    /// T must be a float type (accepts 64-bit but beware that it'll be
    /// interpolated in 32-bit). The tuple count in result array must match the
    /// tuple count in patchpoints. du and dv may be nullptr if not needed.
    template <typename T>
    void                evaluate(T *result, T *du, T *dv,
                            int ptexid, float u, float v,
                            const GT_DataArrayHandle &patchpoints) const
    {
        doEvaluate<T, false>(result, du, dv, ptexid, u, v, patchpoints);
    }

    template <typename T>
    void                evaluateFV(T *result, T *du, T *dv,
                            int ptexid, float u, float v,
                            const GT_DataArrayHandle &patchpoints) const
    {
        doEvaluate<T, true>(result, du, dv, ptexid, u, v, patchpoints);
    }
    /// @}

    /// Get Ptex to base face mapping
    const int *getPtexMap() const { return myPtexToFaceMap.array(); };

private:
    // Get base mesh face id and quadrant given ptex id
    void decodePtex(int &faceid, int &subface, int ptexid) const;

    template <bool FVAR>
    exint totalPatchPointsCount() const;

    template <bool FVAR>
    GT_DataArrayHandle  doPreparePatchPoints(
        const GT_DataArrayHandle &attrdata) const;

    template <typename T, bool FVAR>
    void doEvaluate(T *result, T *du, T *dv,
        int ptexid, float u, float v,
        const GT_DataArrayHandle &patchpoints) const;

    UT_Array<Surface>    mySurfaces;
    UT_Array<GT_Offset>  myPatchOffsets;
    UT_Array<Surface>    myFVSurfaces;
    UT_Array<GT_Offset>  myFVPatchOffsets;
    UT_Array<int>        myPtexToFaceMap;
};

/// Minimal interface to Bfr (base-face representation) for individual face
class GT_API GT_OSDBfrSurface
{
public:
    /// GT_OSDBfrSurface builder
    class GT_API Factory
    {
    public:
        Factory(const GT_OSDTopology &topology);
        ~Factory();
        GT_OSDBfrSurface     build(int faceid);

    private:
        class InternalData;
        UT_UniquePtr<InternalData>   myInternalData;
    };
    static Factory &getFactory();

    /// @{
    /// Calculate patch points to pass to evaluate functions.
    /// Input attrdata must be of float type. Returns GT_DANumeric of same
    /// type. Using fpreal32 storage is highly recommended for performance
    /// reasons. It's up to the caller to store and manage the returned data
    /// for reuse. May return nullptr if unknown data type. 
    GT_DataArrayHandle  preparePatchPoints(
                            const GT_DataArrayHandle &attrdata) const
    {
        return doPreparePatchPoints<false>(attrdata);
    }

    GT_DataArrayHandle  preparePatchPointsFV(
                            const GT_DataArrayHandle &attrdata) const
    {
        return doPreparePatchPoints<true>(attrdata);
    }
    /// @}

    /// @{
    /// Evaluate attribute and its derivs at specified coordinate.
    /// subface index can be obtained by counting digits to subtract from
    /// ptexid until it maps to a different face (using ptex->face mapping from
    /// GT_OSDTopology). T must be a float type (accepts 64-bit but beware that
    /// it'll be interpolated in 32-bit). The tuple count in result array must
    /// match the tuple count in patchpoints. du and dv may be nullptr if not
    /// needed.
    template <typename T>
    void                evaluate(T *result, T *du, T *dv,
                            int subface, float u, float v,
                            const GT_DataArrayHandle &patchpoints) const
    {
        doEvaluate<T, false>(result, du, dv, subface, u, v, patchpoints);
    }

    template <typename T>
    void                evaluateFV(T *result, T *du, T *dv,
                            int subface, float u, float v,
                            const GT_DataArrayHandle &patchpoints) const
    {
        doEvaluate<T, true>(result, du, dv, subface, u, v, patchpoints);
    }
    /// @}

private:
    template <bool FVAR>
    GT_DataArrayHandle  doPreparePatchPoints(
        const GT_DataArrayHandle &attrdata) const;

    template <typename T, bool FVAR>
    void doEvaluate(T *result, T *du, T *dv,
        int subface, float u, float v,
        const GT_DataArrayHandle &patchpoints) const;

    using Surface = OpenSubdiv::Bfr::Surface<fpreal32>;
    Surface      mySurface;
    Surface      myFVSurface;
};

/// Interface to perform limit surface evaluation.
class GT_API GT_OSDLimitSurface
{
public:
    using TopologyRefiner = OpenSubdiv::Far::TopologyRefiner;
    using PtexIndices = OpenSubdiv::Far::PtexIndices;
    using PatchTable = OpenSubdiv::Far::PatchTable;
    using PatchMap = OpenSubdiv::Far::PatchMap;
    using PatchTableFactory = OpenSubdiv::Far::PatchTableFactory;
    using AttribId = GT_OSDAttributes::AttribId;
    using VertexStorage = GT_OSDAttributes::VertexStorage;
    using Vertex = GT_OSDAttributes::Vertex;

    GT_OSDLimitSurface(const GT_OSDTopology &topology,
                        const GT_OSDPatchTableOptions &options,
                        const GT_OSDPatchTable &patchTable,
                        const GT_PrimPolygonMesh &mesh);
    ~GT_OSDLimitSurface();

    void        dump() const;
    void        dump(UT_JSONWriter &w) const;

    /// Return the number of patches
    int         ptexFaceCount() const;

    /// Return the first ptex patch associated with the given coarse face
    int         ptexFromFace(GT_Size face_index) const;
    /// @{
    /// Return the number of ptex patches for the given coarse face
    int         numPtexPatches(const TopologyRefiner &refiner,
                        GT_Size face_index) const;
    int         numPtexPatches(const GT_OSDTopology &top,
                        GT_Size face_index) const
                    { return numPtexPatches(*top.refiner(), face_index); }
    /// @}

    /// Return the coarse face associated with the given ptex id
    GT_Size     faceFromPtex(int ptex_id, int &offset) const;

    /// @{
    /// Query the points/vertices for a face in the coarse mesh
    bool        coarsePoints(const GT_OSDTopology &topology,
                            GT_Size coarse_face_index,
                            GT_Size *vertices,
                            GT_Size buffer_size) const;
    bool        coarseVertices(const GT_OSDTopology &topology,
                            GT_Size coarse_face_index,
                            GT_Size *vertices,
                            GT_Size buffer_size) const;
    /// @}

    /// Evaluate the limit surface (and derivatives) at a given coordinates.
    /// The @c faces array should have @c npts entries.  The @c u and @c v
    /// arrays should have also have @c npts entries.  Each @c u and @c v
    /// coordinate will be offset by @c uv_stride entries.  So, if you have
    /// uv's that are interleaved (i.e. [u0 v0 u1 v1 u2 v2 ...]), you can
    /// offset the @c v pointer and set the stride to 2.
    ///
    /// Passing a @c nullptr for any of the results will disable evaluation of
    /// that property.
    ///
    /// The method returns the tuple size of the attribute evaluated.
    int                 limitSurface(GT_DataArrayHandle *result,
                                GT_DataArrayHandle *result_du,
                                GT_DataArrayHandle *result_dv,
                                const GT_OSDAttributes &alist,
                                const AttribId &attrib,
                                int npts,
                                const int32 *faces,
                                const fpreal32 *u,
                                const fpreal32 *v,
                                int uv_stride = 1,
                                int seg = 0) const;

    /// Evaluation of face-varying attributes on the limit surface
    int                 limitSurfaceFVar(const GT_OSDTopology &topology,
                                GT_DataArrayHandle *result,
                                GT_DataArrayHandle *result_du,
                                GT_DataArrayHandle *result_dv,
                                const GT_OSDAttributes &alist,
                                const AttribId &attrib,
                                int npts,
                                const int32 *faces,
                                const fpreal32 *u,
                                const fpreal32 *v,
                                int uv_stride = 1,
                                int seg = 0) const;

    /// Evaluate the limit surface (and derivatives) at the given coordinates.
    /// The @c faces array should have @c npts entries.  The @c u and @c v
    /// arrays should have also have @c npts entries.  Each @c u and @c v
    /// coordinate will be offset by @c uv_stride entries.  So, if you have
    /// uv's that are interleaved (i.e. [u0 v0 u1 v1 u2 v2 ...]), you can
    /// offset the @c v pointer and set the stride to 2.
    ///
    /// All pointers are required in this version.
    ///
    /// The method returns the tuple size of the attribute evaluated.
    int                 limitSurface(GT_DataArrayHandle *result,
                                GT_DataArrayHandle *result_du,
                                GT_DataArrayHandle *result_dv,
                                GT_DataArrayHandle *result_duu,
                                GT_DataArrayHandle *result_duv,
                                GT_DataArrayHandle *result_dvv,
                                const GT_OSDAttributes &alist,
                                const AttribId &attrib,
                                int npts,
                                const int32 *faces,
                                const fpreal32 *u,
                                const fpreal32 *v,
                                int uv_stride = 1,
                                int seg = 0) const;

    /// Evaluation of face-varying attributes on the limit surface
    int                 limitSurfaceFVar(const GT_OSDTopology &topology,
                                GT_DataArrayHandle *result,
                                GT_DataArrayHandle *result_du,
                                GT_DataArrayHandle *result_dv,
                                GT_DataArrayHandle *result_duu,
                                GT_DataArrayHandle *result_duv,
                                GT_DataArrayHandle *result_dvv,
                                const GT_OSDAttributes &alist,
                                const AttribId &attrib,
                                int npts,
                                const int32 *faces,
                                const fpreal32 *u,
                                const fpreal32 *v,
                                int uv_stride = 1,
                                int seg = 0) const;

private:
    // Maps coarse face -> ptex
    UT_UniquePtr<PtexIndices>   myPtexIndices;
    // Holds all patches and also a map for ptex -> face
    const GT_OSDPatchTable      &myPatches;
    // Maps (coarse face + (u,v)) -> sub patch
    UT_UniquePtr<PatchMap>      myPatchMap;
    //VertexStorage             myStorage;
    GT_CountArray               myFaceOffsets;
};

#endif