//
// Copyright 2016 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.
//
#ifndef PXR_IMAGING_HD_ST_TRIANGULATE_H
#define PXR_IMAGING_HD_ST_TRIANGULATE_H

#include "pxr/pxr.h"
#include "pxr/imaging/hd/version.h"
#include "pxr/imaging/hd/bufferSource.h"

#include "pxr/usd/sdf/path.h"

PXR_NAMESPACE_OPEN_SCOPE


class HdSt_MeshTopology;

/// \class HdSt_TriangleIndexBuilderComputation
///
/// Triangle indices computation CPU.
///

// Index triangulation generates a mapping from triangle ID to authored
// face index domain, called primitiveParams. The primitive params are stored
// alongside topology index buffers, so that the same aggregation locators can
// be used for such an additional buffer as well. This change transforms index
// buffer from int array to int[3] array or int[4] array at first. Thanks to
// the heterogenius non-interleaved buffer aggregation ability in hd,
// we'll get this kind of buffer layout:
//
// ----+--------+--------+------
// ... |i0 i1 i2|i3 i4 i5| ...   index buffer (for triangles)
// ----+--------+--------+------
// ... |   m0   |   m1   | ...   primitive param buffer (coarse face index)
// ----+--------+--------+------

class HdSt_TriangleIndexBuilderComputation : public HdComputedBufferSource {
public:
    HdSt_TriangleIndexBuilderComputation(HdSt_MeshTopology *topology,
                                         SdfPath const &id);
    virtual void GetBufferSpecs(HdBufferSpecVector *specs) const override;
    virtual bool Resolve() override;

    virtual bool HasChainedBuffer() const override;
    virtual HdBufferSourceSharedPtrVector GetChainedBuffers() const override;

protected:
    virtual bool _CheckValid() const override;

private:
    SdfPath const _id;
    HdSt_MeshTopology *_topology;
    HdBufferSourceSharedPtr _primitiveParam;
    HdBufferSourceSharedPtr _trianglesEdgeIndices;
};

//

/// \class HdSt_TriangulateFaceVaryingComputation
///
/// CPU face-varying triangulation.
///
class HdSt_TriangulateFaceVaryingComputation : public HdComputedBufferSource {
public:
    HdSt_TriangulateFaceVaryingComputation(HdSt_MeshTopology *topolgoy,
                                         HdBufferSourceSharedPtr const &source,
                                         SdfPath const &id);

    virtual void GetBufferSpecs(HdBufferSpecVector *specs) const override;
    virtual bool Resolve() override;

protected:
    virtual bool _CheckValid() const override;

private:
    SdfPath const _id;
    HdSt_MeshTopology *_topology;
    HdBufferSourceSharedPtr _source;
};


PXR_NAMESPACE_CLOSE_SCOPE

#endif  // HdSt_TRIANGULATE_H