OpenSubdiv/opensubdiv/far/subdivisionTables.h

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#ifndef FAR_SUBDIVISION_TABLES_H
#define FAR_SUBDIVISION_TABLES_H

#include <cassert>
#include <utility>
#include <vector>

#include "../version.h"
#include "../far/table.h"

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

template <class U> class FarMesh;
template <class U> class FarDispatcher;

// Catmull-Clark tables store the indexing tables required in order to compute
// the refined positions of a mesh without the help of a hierarchical data
// structure. The advantage of this representation is its ability to be executed
// in a massively parallel environment without data dependencies.
//
// The vertex indexing tables require the vertex buffer to be sorted based on the
// nature of the parent of a given vertex : either a face, an edge, or a vertex.
//
// [...Child of a Face...]|[... Child of an Edge ...]|[... Child of a Vertex ...]
//
// Each segment of the buffer is associated the following tables (<T> is the type):
// _<T>_IT : indices of all the adjacent vertices required by the compute kernels
// _<T>_W : fractional weight of the vertex (based on sharpness & topology)
// _<T>_ITa : codex for the two previous tables

// For more details see : "Feature Adaptive GPU Rendering of Catmull-Clark
// Subdivision Surfaces"  p.3 - par. 3.2
template <class U> class FarSubdivisionTables {
public:

    // Destructor
    virtual ~FarSubdivisionTables<U>() {}

    // Return the highest level of subdivision possible with these tables
    int GetMaxLevel() const { return (int)(_vertsOffsets.size()); }

    // Memory required to store the indexing tables
    virtual int GetMemoryUsed() const;

    // Compute the positions of refined vertices using the specified kernels
    virtual void Apply( int level, void * clientdata=0 ) const=0;

    // Pointer back to the mesh owning the table
    FarMesh<U> * GetMesh() { return _mesh; }

    // The index of the first vertex that belongs to the level of subdivision
    // represented by this set of FarCatmarkSubdivisionTables
    int GetFirstVertexOffset( int level ) const;

    // Number of vertices children of a face at a given level (always 0 for Loop)
    int GetNumFaceVertices( int level ) const;

    // Number of vertices children of an edge at a given level
    int GetNumEdgeVertices( int level ) const;

    // Number of vertices children of a vertex at a given level
    int GetNumVertexVertices( int level ) const;

    // Total number of vertices at a given level
    int GetNumVertices( int level ) const;

    // Indexing tables accessors

    // Returns the edge vertices indexing table
    FarTable<int> const &          Get_E_IT() const { return _E_IT; }

    // Returns the edge vertices weights table
    FarTable<float> const &        Get_E_W() const { return _E_W; }

    // Returns the vertex vertices codex table
    FarTable<int> const &          Get_V_ITa() const { return _V_ITa; }

    // Returns the vertex vertices indexing table
    FarTable<unsigned int> const & Get_V_IT() const { return _V_IT; }

    // Returns the vertex vertices weights table
    FarTable<float> const &        Get_V_W() const { return _V_W; }

    // Returns the number of indexing tables needed to represent this particular
    // subdivision scheme.
    virtual int GetNumTables() const { return 5; }

protected:
    template <class X, class Y> friend class FarMeshFactory;

    FarSubdivisionTables<U>( FarMesh<U> * mesh, int maxlevel );

    // Returns an integer based on the order in which the kernels are applied
    static int getMaskRanking( unsigned char mask0, unsigned char mask1 );

    struct VertexKernelBatch {
        int kernelF; // number of face vertices
        int kernelE; // number of edge vertices

        std::pair<int,int> kernelB;  // first / last vertex vertex batch (kernel B)
        std::pair<int,int> kernelA1; // first / last vertex vertex batch (kernel A pass 1)
        std::pair<int,int> kernelA2; // first / last vertex vertex batch (kernel A pass 2)

        VertexKernelBatch() : kernelF(0), kernelE(0) { }

        void InitVertexKernels(int a, int b) {
            kernelB.first = kernelA1.first = kernelA2.first = a;
            kernelB.second = kernelA1.second = kernelA2.second = b;
        }

        void AddVertex( int index, int rank ) {
            // expand the range of kernel batches based on vertex index and rank
            if (rank<7) {
                if (index < kernelB.first)
                    kernelB.first=index;
                if (index > kernelB.second)
                    kernelB.second=index;
            }
            if ((rank>2) and (rank<8)) {
                if (index < kernelA2.first)
                    kernelA2.first=index;
                if (index > kernelA2.second)
                    kernelA2.second=index;
            }
            if (rank>6) {
                if (index < kernelA1.first)
                    kernelA1.first=index;
                if (index > kernelA1.second)
                    kernelA1.second=index;
            }
        }
    };

    // Returns the range of vertex indices of each of the 3 batches of VertexPoint
    // compute Kernels (kernel application order is : B / A / A)
    std::vector<VertexKernelBatch> & getKernelBatches() const { return _batches; }

protected:
    // mesh that owns this subdivisionTable
    FarMesh<U> * _mesh;

    FarTable<int>          _E_IT;  // vertices from edge refinement
    FarTable<float>        _E_W;   // weigths

    FarTable<int>          _V_ITa; // vertices from vertex refinement
    FarTable<unsigned int> _V_IT;  // indices of adjacent vertices
    FarTable<float>        _V_W;   // weights

    std::vector<VertexKernelBatch> _batches; // batches of vertices for kernel execution

    std::vector<int> _vertsOffsets; // offset to the first vertex of each level
private:
};

template <class U>
FarSubdivisionTables<U>::FarSubdivisionTables( FarMesh<U> * mesh, int maxlevel ) :
    _mesh(mesh),
    _E_IT(maxlevel+1),
    _E_W(maxlevel+1),
    _V_ITa(maxlevel+1),
    _V_IT(maxlevel+1),
    _V_W(maxlevel+1),
    _batches(maxlevel),
    _vertsOffsets(maxlevel+1,0)
{
    assert( maxlevel > 0 );
}

// The ranking matrix defines the order of execution for the various combinations
// of Corner, Crease, Dart and Smooth topological configurations. This matrix is
// somewhat arbitrary as it is possible to perform some permutations in the
// ordering without adverse effects, but it does try to minimize kernel switching
// during the exececution of Apply(). This table is identical for both the Loop
// and Catmull-Clark schemes.
//
// The matrix is derived from this table :
// Rules     +----+----+----+----+----+----+----+----+----+----+
//   Pass 0  | Dt | Sm | Sm | Dt | Sm | Dt | Sm | Cr | Co | Cr |
//   Pass 1  |    |    |    | Co | Co | Cr | Cr | Co |    |    |
// Kernel    +----+----+----+----+----+----+----+----+----+----+
//   Pass 0  | B  | B  | B  | B  | B  | B  | B  | A  | A  | A  |
//   Pass 1  |    |    |    | A  | A  | A  | A  | A  |    |    |
//           +----+----+----+----+----+----+----+----+----+----+
// Rank      | 0  | 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  |
//           +----+----+----+----+----+----+----+----+----+----+
// with :
//     - A : compute kernel applying k_Crease / k_Corner rules
//     - B : compute kernel applying k_Smooth / k_Dart rules
template <class U> int
FarSubdivisionTables<U>::getMaskRanking( unsigned char mask0, unsigned char mask1 ) {
    static short masks[4][4] = { {    0,    1,    6,    4 },
                                 { 0xFF,    2,    5,    3 },
                                 { 0xFF, 0xFF,    9,    7 },
                                 { 0xFF, 0xFF, 0xFF,    8 } };
    return masks[mask0][mask1];
}

template <class U> int
FarSubdivisionTables<U>::GetFirstVertexOffset( int level ) const {
    assert(level>=0 and level<=(int)_vertsOffsets.size());
    return _vertsOffsets[level];
}

template <class U> int
FarSubdivisionTables<U>::GetNumFaceVertices( int level ) const {
    assert(level>=0 and level<=(int)_batches.size());
    return _batches[level-1].kernelF;
}

template <class U> int
FarSubdivisionTables<U>::GetNumEdgeVertices( int level ) const {
    assert(level>=0 and level<=(int)_batches.size());
    return _batches[level-1].kernelE;
}

template <class U> int
FarSubdivisionTables<U>::GetNumVertexVertices( int level ) const {
    assert(level>=0 and level<=(int)_batches.size());
    if (level==0)
        return _mesh->GetNumCoarseVertices();
    else
        return std::max( _batches[level-1].kernelB.second,
                   std::max(_batches[level-1].kernelA1.second,
                       _batches[level-1].kernelA2.second));
}

template <class U> int
FarSubdivisionTables<U>::GetNumVertices( int level ) const {
    assert(level>=0 and level<=(int)_batches.size());
    if (level==0)
        return GetNumVertexVertices(0);
    else
        return GetNumFaceVertices(level)+
               GetNumEdgeVertices(level)+
               GetNumVertexVertices(level);
}

template <class U> int
FarSubdivisionTables<U>::GetMemoryUsed() const {
    return _E_IT.GetMemoryUsed()+
           _E_W.GetMemoryUsed()+
           _V_ITa.GetMemoryUsed()+
           _V_IT.GetMemoryUsed()+
           _V_W.GetMemoryUsed();
}

} // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

} // end namespace OpenSubdiv

#endif /* FAR_SUBDIVISION_TABLES_H */