OpenSubdiv/opensubdiv/far/loopSubdivisionTables.h

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#ifndef FAR_LOOP_SUBDIVISION_TABLES_H
#define FAR_LOOP_SUBDIVISION_TABLES_H

#include "../version.h"

#include "../far/subdivisionTables.h"

#include <cassert>
#include <cmath>
#include <vector>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

/// \brief Loop subdivision scheme tables.
///
/// Loop 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.
///
template <class U> class FarLoopSubdivisionTables : public FarSubdivisionTables<U> {

public:

private:
    template <class X, class Y> friend class FarLoopSubdivisionTablesFactory;
    template <class X, class Y> friend class FarMultiMeshFactory;
    template <class CONTROLLER> friend class FarComputeController;

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

    // Compute-kernel applied to vertices resulting from the refinement of an edge.
    void computeEdgePoints(int offset, int level, int start, int end, void * clientdata) const;

    // Compute-kernel applied to vertices resulting from the refinement of a vertex
    // Kernel "A" Handles the k_Smooth and k_Dart rules
    void computeVertexPointsA(int offset, bool pass, int level, int start, int end, void * clientdata) const;

    // Compute-kernel applied to vertices resulting from the refinement of a vertex
    // Kernel "B" Handles the k_Crease and k_Corner rules
    void computeVertexPointsB(int offset,int level, int start, int end, void * clientdata) const;
};

template <class U>
FarLoopSubdivisionTables<U>::FarLoopSubdivisionTables( FarMesh<U> * mesh, int maxlevel ) :
    FarSubdivisionTables<U>(mesh, maxlevel)
{ }

//
// Edge-vertices compute Kernel - completely re-entrant
//

template <class U> void
FarLoopSubdivisionTables<U>::computeEdgePoints( int offset, int tableOffset, int start, int end, void * clientdata ) const {

    assert(this->_mesh);

    U * vsrc = &this->_mesh->GetVertices().at(0),
      * vdst = vsrc + offset + start;

    for (int i=start+tableOffset; i<end+tableOffset; ++i, ++vdst ) {

        vdst->Clear(clientdata);

        int eidx0 = this->_E_IT[4*i+0],
            eidx1 = this->_E_IT[4*i+1],
            eidx2 = this->_E_IT[4*i+2],
            eidx3 = this->_E_IT[4*i+3];

        float endPtWeight = this->_E_W[i*2+0];

        // Fully sharp edge : endPtWeight = 0.5f
        vdst->AddWithWeight( vsrc[eidx0], endPtWeight, clientdata );
        vdst->AddWithWeight( vsrc[eidx1], endPtWeight, clientdata );

        if (eidx2!=-1) {
            // Apply fractional sharpness
            float oppPtWeight = this->_E_W[i*2+1];

            vdst->AddWithWeight( vsrc[eidx2], oppPtWeight, clientdata );
            vdst->AddWithWeight( vsrc[eidx3], oppPtWeight, clientdata );
        }

        vdst->AddVaryingWithWeight( vsrc[eidx0], 0.5f, clientdata );
        vdst->AddVaryingWithWeight( vsrc[eidx1], 0.5f, clientdata );
    }
}

//
// Vertex-vertices compute Kernels "A" and "B" - completely re-entrant
//

// multi-pass kernel handling k_Crease and k_Corner rules
template <class U> void
FarLoopSubdivisionTables<U>::computeVertexPointsA( int offset, bool pass, int tableOffset, int start, int end, void * clientdata ) const {

    assert(this->_mesh);

    U * vsrc = &this->_mesh->GetVertices().at(0),
      * vdst = vsrc + offset + start;

    for (int i=start+tableOffset; i<end+tableOffset; ++i, ++vdst ) {

        if (not pass)
            vdst->Clear(clientdata);

        int     n=this->_V_ITa[5*i+1], // number of vertices in the _VO_IT array (valence)
                p=this->_V_ITa[5*i+2], // index of the parent vertex
            eidx0=this->_V_ITa[5*i+3], // index of the first crease rule edge
            eidx1=this->_V_ITa[5*i+4]; // index of the second crease rule edge

        float weight = pass ? this->_V_W[i] : 1.0f - this->_V_W[i];

        // In the case of fractional weight, the weight must be inverted since
        // the value is shared with the k_Smooth kernel (statistically the
        // k_Smooth kernel runs much more often than this one)
        if (weight>0.0f and weight<1.0f and n>0)
            weight=1.0f-weight;

        // In the case of a k_Corner / k_Crease combination, the edge indices
        // won't be null,  so we use a -1 valence to detect that particular case
        if (eidx0==-1 or (pass==false and (n==-1)) ) {
            // k_Corner case
            vdst->AddWithWeight( vsrc[p], weight, clientdata );
        } else {
            // k_Crease case
            vdst->AddWithWeight( vsrc[p], weight * 0.75f, clientdata );
            vdst->AddWithWeight( vsrc[eidx0], weight * 0.125f, clientdata );
            vdst->AddWithWeight( vsrc[eidx1], weight * 0.125f, clientdata );
        }
        vdst->AddVaryingWithWeight( vsrc[p], 1.0f, clientdata );
    }
}

// multi-pass kernel handling k_Dart and k_Smooth rules
template <class U> void
FarLoopSubdivisionTables<U>::computeVertexPointsB( int offset, int tableOffset, int start, int end, void * clientdata ) const {

    assert(this->_mesh);

    U * vsrc = &this->_mesh->GetVertices().at(0),
      * vdst = vsrc + offset + start;

    for (int i=start+tableOffset; i<end+tableOffset; ++i, ++vdst ) {

        vdst->Clear(clientdata);

        int h = this->_V_ITa[5*i  ], // offset of the vertices in the _V0_IT array
            n = this->_V_ITa[5*i+1], // number of vertices in the _VO_IT array (valence)
            p = this->_V_ITa[5*i+2]; // index of the parent vertex

        float weight = this->_V_W[i],
                  wp = 1.0f/n,
                beta = 0.25f * cosf((float)M_PI * 2.0f * wp) + 0.375f;
        beta = beta*beta;
        beta = (0.625f-beta)*wp;

        vdst->AddWithWeight( vsrc[p], weight * (1.0f-(beta*n)), clientdata);

        for (int j=0; j<n; ++j)
            vdst->AddWithWeight( vsrc[this->_V_IT[h+j]], weight * beta );

        vdst->AddVaryingWithWeight( vsrc[p], 1.0f, clientdata );
    }
}

} // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

} // end namespace OpenSubdiv

#endif /* FAR_LOOP_SUBDIVISION_TABLES_H */