OpenSubdiv/opensubdiv/far/patchMap.cpp

//
//   Copyright 2014 DreamWorks Animation LLC.
//
//   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/patchMap.h"

#include <algorithm>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

namespace Far {

// Constructor
PatchMap::PatchMap( PatchTable const & patchTable ) {
    initialize( patchTable );
}

// sets all the children to point to the patch of index patchIdx
void
PatchMap::QuadNode::SetChild(int patchIdx) {
    for (int i=0; i<4; ++i) {
        children[i].isSet=true;
        children[i].isLeaf=true;
        children[i].idx=patchIdx;
    }
}

// sets the child in "quadrant" to point to the node or patch of the given index
void
PatchMap::QuadNode::SetChild(unsigned char quadrant, int idx, bool isLeaf) {
    assert(quadrant<4);
    children[quadrant].isSet  = true;
    children[quadrant].isLeaf = isLeaf;
    children[quadrant].idx    = idx;
}

// adds a child to a parent node and pushes it back on the tree
PatchMap::QuadNode *
PatchMap::addChild( QuadTree & quadtree, QuadNode * parent, int quadrant ) {
    quadtree.push_back(QuadNode());
    int idx = (int)quadtree.size()-1;
    parent->SetChild(quadrant, idx, false);
    return &(quadtree[idx]);
}

void
PatchMap::initialize( PatchTable const & patchTable ) {

    _patchesAreTriangular =
        patchTable.GetVaryingPatchDescriptor().GetNumControlVertices() == 3;

    int nfaces = 0,
        narrays = (int)patchTable.GetNumPatchArrays(),
        npatches = (int)patchTable.GetNumPatchesTotal();

    if (! narrays || ! npatches)
        return;

    // populate subpatch handles vector
    _handles.resize(npatches);

    for (int parray=0, current=0; parray<narrays; ++parray) {

        ConstPatchParamArray params = patchTable.GetPatchParams(parray);

        int ringsize = patchTable.GetPatchArrayDescriptor(parray).GetNumControlVertices();

        for (Index j=0; j < patchTable.GetNumPatches(parray); ++j) {

            Handle & h = _handles[current];

            h.arrayIndex = parray;
            h.patchIndex = current;
            h.vertIndex  = j * ringsize;

            nfaces = std::max(nfaces, (int)params[j].GetFaceId());

            ++current;
        }
    }
    ++nfaces;
    // temporary vector to hold the quadtree while under construction
    std::vector<QuadNode> quadtree;

    // reserve memory for the octree nodes (size is a worse-case approximation)
    quadtree.reserve( nfaces + npatches );

    // each coarse face has a root node associated to it that we need to initialize
    quadtree.resize(nfaces);

    // populate the quadtree from the FarPatchArrays sub-patches
    for (Index parray=0, handleIndex=0; parray<narrays; ++parray) {

        ConstPatchParamArray params = patchTable.GetPatchParams(parray);

        for (int i=0; i < patchTable.GetNumPatches(parray); ++i, ++handleIndex) {

            PatchParam const & param = params[i];

            QuadNode * node = &quadtree[ param.GetFaceId() ];

            int rootDepth = param.NonQuadRoot();
            int depth = param.GetDepth();

            if (depth == rootDepth) {
                // special case : root level face with no sub-patches
                node->SetChild( handleIndex );
                continue;
            }

            //  We can use the PatchParam bits directly to determine the quadrants
            //  in which to place the patch -- just need to adjust the UV bits for
            //  the special case of a rotated triangular patch:
            //
            int u = param.GetU();
            int v = param.GetV();

            if (_patchesAreTriangular && param.IsTriangleRotated()) {
                u = (1 << depth) - u;
                v = (1 << depth) - v;
            }

            for (int j = rootDepth + 1; j<= depth; ++j) {
                int uBit = (u >> (depth - j)) & 1;
                int vBit = (v >> (depth - j)) & 1;

                int quadrant = (vBit << 1) | uBit;

                if (j == depth) {
                   // we have reached the depth of the sub-patch : add a leaf
                   assert( ! node->children[quadrant].isSet );
                   node->SetChild(quadrant, handleIndex, true);
                } else {
                    // travel down the child node of the corresponding quadrant
                    if (! node->children[quadrant].isSet) {
                        // create a new branch in the quadrant
                        node = addChild(quadtree, node, quadrant);
                    } else {
                        // travel down an existing branch
                        node = &(quadtree[ node->children[quadrant].idx ]);
                    }
                }
            }
        }
    }

    // copy the resulting quadtree to eliminate un-unused vector capacity
    _quadtree = quadtree;
}


} // end namespace Far

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