OpenSubdiv/opensubdiv/far/patchTables.cpp

//
//   Copyright 2013 Pixar
//
//   Licensed under the Apache License, Version 2.0 (the "Apache License")
//   with the following modification; you may not use this file except in
//   compliance with the Apache License and the following modification to it:
//   Section 6. Trademarks. is deleted and replaced with:
//
//   6. Trademarks. This License does not grant permission to use the trade
//      names, trademarks, service marks, or product names of the Licensor
//      and its affiliates, except as required to comply with Section 4(c) of
//      the License and to reproduce the content of the NOTICE file.
//
//   You may obtain a copy of the Apache License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the Apache License with the above modification is
//   distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
//   KIND, either express or implied. See the Apache License for the specific
//   language governing permissions and limitations under the Apache License.
//

#include "../far/patchTables.h"
#include "../far/stencilTables.h"

#include <cstring>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

namespace Far {

static void
getBeziereWeights(float t, float point[4], float deriv[3]) {

    // The weights for the four uniform cubic Bezier basis functions are:
    // (1 - t)^3
    // 3 * t * (1-t)
    // 3 * t^2 * (1-t)
    // t^3
    float t2 = t*t,
          w0 = 1.0f - t,
          w2 = w0 * w0;

    assert(point);
    point[0] = w0*w2;
    point[1] = 3.0f * t * w2;
    point[2] = 3.0f * t2 * w0;
    point[3] = t * t2;

    // The weights for the three uniform quadratic basis functions are:
    // (1-t)^2
    // 2 * t * (1-t)
    // t^2
    if (deriv) {
        deriv[0] = w2;
        deriv[1] = 2.0f * t * w0;
        deriv[2] = t2;
    }
}

static void
getBSplineWeights(float t, float point[4], float deriv[3]) {

    // The weights for the four uniform cubic B-Spline basis functions are:
    // (1/6)(1 - t)^3
    // (1/6)(3t^3 - 6t^2 + 4)
    // (1/6)(-3t^3 + 3t^2 + 3t + 1)
    // (1/6)t^3
    float t2 = t*t,
          t3 = 3.0f*t2*t,
          w0 = 1.0f-t;

    assert(point);
    point[0] = (w0*w0*w0) / 6.0f;
    point[1] = (t3 - 6.0f*t2 + 4.0f) / 6.0f;
    point[2] = (3.0f*t2 - t3 + 3.0f*t + 1.0f) / 6.0f;
    point[3] = t3 / 18.0f;


    // The weights for the three uniform quadratic basis functions are:
    // (1/2)(1-t)^2
    // (1/2)(1 + 2t - 2t^2)
    // (1/2)t^2
    if (deriv) {
        deriv[0] = 0.5f * w0 * w0;
        deriv[1] = 0.5f + t - t2;
        deriv[2] = 0.5f * t2;
    }
}

void
PatchTables::getBasisWeightsAtUV(TensorBasis basis, PatchParam::BitField bits,
    float s, float t, float point[16], float deriv1[16], float deriv2[16]) {

    int const rots[4][16] =
        { { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
          { 12, 8, 4, 0, 13, 9, 5, 1, 14, 10, 6, 2, 15, 11, 7, 3 },
          { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 },
          { 3, 7, 11, 15, 2, 6, 10, 14, 1, 5, 9, 13, 0, 4, 8, 12 } };

    assert(bits.GetRotation()<4);
    int const * rot = rots[bits.GetRotation()];

    float sWeights[4], tWeights[4], d1Weights[3], d2Weights[3];

    if (basis==BASIS_BSPLINE) {
        getBSplineWeights(s, point ? sWeights : 0, deriv1 ? d1Weights : 0);
        getBSplineWeights(t, point ? tWeights : 0, deriv2 ? d2Weights : 0);
    } else if (basis==BASIS_BEZIER) {
        getBeziereWeights(s, point ? sWeights : 0, deriv1 ? d1Weights : 0);
        getBeziereWeights(t, point ? tWeights : 0, deriv2 ? d2Weights : 0);
    } else {
        assert(0);
    }

    if (point) {
        // Compute the tensor product weight corresponding to each control
        // vertex
        memset(point,  0, 16*sizeof(float));
        for (int i = 0; i < 4; ++i) {
            for (int j = 0; j < 4; ++j) {
                point[rot[4*i+j]] += sWeights[j] * tWeights[i];
            }
        }
    }

    if (deriv1 and deriv2) {
        // Compute the tangent stencil. This is done by taking the tensor
        // product between the quadratic weights computed for s and the cubic
        // weights computed for t. The stencil is constructed using
        // differences between consecutive vertices in each row (i.e.
        // in the s direction).
        memset(deriv1, 0, 16*sizeof(float));
        for (int i = 0; i < 4; ++i) {
            float prevWeight = 0.0f;
            for (int j = 0; j < 3; ++j) {
                float weight = d1Weights[j]*tWeights[i];
                deriv1[rot[4*i+j]] += prevWeight - weight;
                prevWeight = weight;
            }
            deriv1[rot[4*i+3]]+=prevWeight;
        }

        memset(deriv2, 0, 16*sizeof(float));
        for (int j = 0; j < 4; ++j) {
            float prevWeight = 0.0f;
            for (int i = 0; i < 3; ++i) {
                float weight = sWeights[j]*d2Weights[i];
                deriv2[rot[4*i+j]]+=prevWeight - weight;
                prevWeight = weight;
            }
            deriv2[rot[12+j]] += prevWeight;
        }

        // Scale derivatives up based on level of subdivision
        float scale = float(1 << bits.GetDepth());
        for (int k=0; k<16; ++k) {
            deriv1[k] *= scale;
            deriv2[k] *= scale;
        }
    }
}

//
// Constructor
//
PatchTables::PatchTables(PatchArrayVector const & patchArrays,
                         PTable const & patches,
                         VertexValenceTable const * vertexValences,
                         QuadOffsetTable const * quadOffsets,
                         StencilTables const * endcapStencilTables,
                         PatchParamTable const * patchParams,
                         FVarPatchTables const * fvarPatchTables,
                         int maxValence) :
    _maxValence(maxValence),
    _numPtexFaces(0),
    _patchArrays(patchArrays),
    _patches(patches),
    _endcapStencilTables(endcapStencilTables),
    _fvarPatchTables(fvarPatchTables) {

    // copy other tables if exist
    if (vertexValences)
        _vertexValenceTable = *vertexValences;
    if (quadOffsets)
        _quadOffsetTable = *quadOffsets;
    if (patchParams)
        _paramTable = *patchParams;
}

PatchTables::~PatchTables() {
    delete _endcapStencilTables;
    delete _fvarPatchTables;
}

bool
PatchTables::IsFeatureAdaptive() const {

    // the vertex valence table is only used by Gregory patches, so the PatchTables
    // contain feature adaptive patches if this is not empty.
    if (not _vertexValenceTable.empty())
        return true;

    // otherwise, we have to check each patch array
    PatchArrayVector const & parrays = GetPatchArrayVector();
    for (int i=0; i<(int)parrays.size(); ++i) {
        if (parrays[i].GetDescriptor().GetType() >= REGULAR and
            parrays[i].GetDescriptor().GetType() <= GREGORY_BASIS)
            return true;
    }
    return false;
}
int
PatchTables::GetNumPatchesTotal() const {
    // there is one PatchParam record for each patch in the mesh
    return (int)GetPatchParamTable().size();
}

//
// Uniform accessors
//
PatchTables::PatchArray const *
PatchTables::GetUniformPatchArray(int level) const {

    if (IsFeatureAdaptive())
        return NULL;

    PatchArrayVector const & parrays = GetPatchArrayVector();

    if (parrays.empty())
        return NULL;

    if (level < 1) {
        return &(*parrays.rbegin());
    } else if ((level-1) < (int)parrays.size() ) {
        return &parrays[level-1];
    }

    return NULL;
}
Index const *
PatchTables::GetUniformFaceVertices(int level) const {

    PatchArray const * parray = GetUniformPatchArray(level);

    if (parray) {
        return &GetPatchTable()[ parray->GetVertIndex() ];
    }
    return NULL;
}
int
PatchTables::GetNumUniformFaces(int level) const {

    PatchArray const * parray = GetUniformPatchArray(level);

    if (parray) {
        return parray->GetNumPatches();
    }
    return -1;
}

//
// Returns a pointer to the array of patches matching the descriptor
//
PatchTables::PatchArray *
PatchTables::findPatchArray( PatchTables::Descriptor desc ) {

    for (int i=0; i<(int)_patchArrays.size(); ++i) {
        if (_patchArrays[i].GetDescriptor()==desc)
            return &_patchArrays[i];
    }
    return 0;
}


//
// Lists of patch Descriptors for each subdivision scheme
//
PatchTables::DescriptorVector const &
PatchTables::getAdaptiveCatmarkDescriptors() {

    static DescriptorVector _descriptors;

    if (_descriptors.empty()) {

        _descriptors.reserve(71);

        // non-transition patches : 6
        for (int i=REGULAR; i<=GREGORY_BASIS; ++i) {
            _descriptors.push_back( Descriptor(i, NON_TRANSITION, 0) );
        }

        // transition patches (1 + 4 * 3) * 5 = 65
        for (int i=PATTERN0; i<=PATTERN4; ++i) {

            _descriptors.push_back( Descriptor(REGULAR, i, 0) );

            // 4 rotations for single-crease, boundary and corner patches
            for (int j=0; j<4; ++j) {
                _descriptors.push_back( Descriptor(SINGLE_CREASE, i, j) );
            }

            for (int j=0; j<4; ++j) {
                _descriptors.push_back( Descriptor(BOUNDARY, i, j) );
            }

            for (int j=0; j<4; ++j) {
                _descriptors.push_back( Descriptor(CORNER, i, j) );
            }
        }
    }
    return _descriptors;
}

PatchTables::DescriptorVector const &
PatchTables::getAdaptiveLoopDescriptors() {

    static DescriptorVector _descriptors;

    if (_descriptors.empty()) {
        _descriptors.reserve(1);
        _descriptors.push_back( Descriptor(LOOP, NON_TRANSITION, 0) );
    }
    return _descriptors;
}

PatchTables::DescriptorVector const &
PatchTables::GetAdaptiveDescriptors(Sdc::Type type) {

    static DescriptorVector _empty;

    switch (type) {
        case Sdc::TYPE_CATMARK : return getAdaptiveCatmarkDescriptors();
        case Sdc::TYPE_LOOP    : return getAdaptiveLoopDescriptors();
        default:
          assert(0);
    }
    return _empty;
}

} // end namespace Far

} // end namespace OPENSUBDIV_VERSION
} // end namespace OpenSubdiv