OpenSubdiv/opensubdiv/osd/glXFBEvaluator.h

//
//   Copyright 2015 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.
//

#pragma once
#ifndef OPENSUBDIV3_OSD_GL_XFB_EVALUATOR_H
#define OPENSUBDIV3_OSD_GL_XFB_EVALUATOR_H

#include "../version.h"

#include "../osd/opengl.h"
#include "../osd/vertexDescriptor.h"

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

namespace Far {
    class StencilTables;
}

namespace Osd {

/// \brief GL TextureBuffer stencil tables
///
/// This class is a GL Texture Buffer representation of Far::StencilTables.
///
/// GLSLTransformFeedback consumes this table to apply stencils
///
///
class GLStencilTablesTBO {
public:
    static GLStencilTablesTBO *Create(
        Far::StencilTables const *stencilTables, void *deviceContext = NULL) {
        (void)deviceContext;  // unused
        return new GLStencilTablesTBO(stencilTables);
    }

    explicit GLStencilTablesTBO(Far::StencilTables const *stencilTables);
    ~GLStencilTablesTBO();

    // interfaces needed for GLSLTransformFeedbackKernel
    GLuint GetSizesTexture() const { return _sizes; }
    GLuint GetOffsetsTexture() const { return _offsets; }
    GLuint GetIndicesTexture() const { return _indices; }
    GLuint GetWeightsTexture() const { return _weights; }
    int GetNumStencils() const { return _numStencils; }

private:
    GLuint _sizes;
    GLuint _offsets;
    GLuint _indices;
    GLuint _weights;
    int _numStencils;
};

// ---------------------------------------------------------------------------

class GLXFBEvaluator {
public:
    typedef bool Instantiatable;
    static GLXFBEvaluator * Create(VertexBufferDescriptor const &srcDesc,
                                   VertexBufferDescriptor const &dstDesc,
                                   void * deviceContext = NULL) {
        (void)deviceContext;  // not used
        GLXFBEvaluator *instance = new GLXFBEvaluator();
        if (instance->Compile(srcDesc, dstDesc)) return instance;
        delete instance;
        return NULL;
    }

    /// Constructor.
    GLXFBEvaluator();

    /// Destructor. note that the GL context must be made current.
    ~GLXFBEvaluator();

    /// \brief Generic static stencil function. This function has a same
    ///        signature as other device kernels have so that it can be called
    ///        transparently from OsdMesh template interface.
    ///
    /// @param srcBuffer      Input primvar buffer.
    ///                       must have BindVBO() method returning a
    ///                       const float pointer for read
    ///
    /// @param srcDesc        vertex buffer descriptor for the input buffer
    ///
    /// @param dstBuffer      Output primvar buffer
    ///                       must have BindVBO() method returning a
    ///                       float pointer for write
    ///
    /// @param dstDesc        vertex buffer descriptor for the output buffer
    ///
    /// @param stencilTable   stencil table to be applied. The table must have
    ///                       Texture Buffer Object interfaces.
    ///
    /// @param instance       cached compiled instance. Clients are supposed to
    ///                       pre-compile an instance of this class and provide
    ///                       to this function. If it's null the kernel still
    ///                       compute by instantiating on-demand kernel although
    ///                       it may cause a performance problem.
    ///
    /// @param deviceContext  not used in the GLSLTransformFeedback kernel
    ///
    template <typename VERTEX_BUFFER, typename STENCIL_TABLE>
    static bool EvalStencils(VERTEX_BUFFER *srcVertexBuffer,
                             VertexBufferDescriptor const &srcDesc,
                             VERTEX_BUFFER *dstVertexBuffer,
                             VertexBufferDescriptor const &dstDesc,
                             STENCIL_TABLE const *stencilTable,
                             GLXFBEvaluator const *instance,
                             void * deviceContext = NULL) {
        if (instance) {
            return instance->EvalStencils(srcVertexBuffer, srcDesc,
                                          dstVertexBuffer, dstDesc,
                                          stencilTable);
        } else {
            // Create an instance on demand (slow)
            (void)deviceContext;  // unused
            instance = Create(srcDesc, dstDesc);
            if (instance) {
                bool r = instance->EvalStencils(srcVertexBuffer, srcDesc,
                                                dstVertexBuffer, dstDesc,
                                                stencilTable);
                delete instance;
                return r;
            }
            return false;
        }
    }

    /// Dispatch the GLSL compute kernel on GPU asynchronously.
    /// returns false if the kernel hasn't been compiled yet.
    template <typename VERTEX_BUFFER, typename STENCIL_TABLE>
    bool EvalStencils(VERTEX_BUFFER *srcVertexBuffer,
                      VertexBufferDescriptor const &srcDesc,
                      VERTEX_BUFFER *dstVertexBuffer,
                      VertexBufferDescriptor const &dstDesc,
                      STENCIL_TABLE const *stencilTable) const {
        return EvalStencils(srcVertexBuffer->BindVBO(),
                            srcDesc,
                            dstVertexBuffer->BindVBO(),
                            dstDesc,
                            stencilTable->GetSizesTexture(),
                            stencilTable->GetOffsetsTexture(),
                            stencilTable->GetIndicesTexture(),
                            stencilTable->GetWeightsTexture(),
                            /* start = */ 0,
                            /* end   = */ stencilTable->GetNumStencils());
    }

    /// Dispatch the GLSL compute kernel on GPU asynchronously.
    /// returns false if the kernel hasn't been compiled yet.
    bool EvalStencils(GLuint srcBuffer,
                      VertexBufferDescriptor const &srcDesc,
                      GLuint dstBuffer,
                      VertexBufferDescriptor const &dstDesc,
                      GLuint sizesBuffer,
                      GLuint offsetsBuffer,
                      GLuint indicesBuffer,
                      GLuint weightsBuffer,
                      int start,
                      int end) const;

    /// Configure GLSL kernel. A valid GL context must be made current before
    /// calling this function. Returns false if it fails to compile the kernel.
    bool Compile(VertexBufferDescriptor const &srcDesc,
                 VertexBufferDescriptor const &dstDesc);

    /// Wait the dispatched kernel finishes.
    static void Synchronize(void *kernel);

private:
    GLuint _program;

    GLuint _srcBufferTexture;

    GLuint _uniformSrcBufferTexture;
    GLuint _uniformSizesTexture;
    GLuint _uniformOffsetsTexture;
    GLuint _uniformIndicesTexture;
    GLuint _uniformWeightsTexture;

    GLuint _uniformStart;     // range
    GLuint _uniformEnd;
    GLuint _uniformSrcOffset;    // src buffer offset (in elements)
};

}  // end namespace Osd

}  // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

}  // end namespace OpenSubdiv


#endif  // OPENSUBDIV3_OSD_GL_XFB_EVALUATOR_H