text: //
  // 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_RENDER_PASS_SHADER_H
  #define PXR_IMAGING_HD_ST_RENDER_PASS_SHADER_H
  
  #include "pxr/pxr.h"
  #include "pxr/imaging/hdSt/api.h"
  #include "pxr/imaging/hd/enums.h"
  #include "pxr/imaging/hd/binding.h"
  #include "pxr/imaging/hdSt/shaderCode.h"
  #include "pxr/imaging/hio/glslfx.h"
  
  #include "pxr/base/tf/declarePtrs.h"
  #include "pxr/base/tf/token.h"
  
  #include <memory>
  
  PXR_NAMESPACE_OPEN_SCOPE
  
  using HdStRenderPassShaderSharedPtr =
      std::shared_ptr<class HdStRenderPassShader>;
  class HdRenderIndex;
  using HdRenderPassAovBindingVector =
      std::vector<struct HdRenderPassAovBinding>;
  
  /// \class HdStRenderPassShader
  ///
  /// A shader that supports common renderPass functionality.
  ///
  class HdStRenderPassShader : public HdStShaderCode {
  public:
      HDST_API
      HdStRenderPassShader();
      HDST_API
      HdStRenderPassShader(TfToken const &glslfxFile);
      HDST_API
      ~HdStRenderPassShader() override;
  
      /// HdShader overrides
      HDST_API
      ID ComputeHash() const override;
      HDST_API
      std::string GetSource(TfToken const &shaderStageKey) const override;
      HDST_API
      void BindResources(int program,
                         HdSt_ResourceBinder const &binder) override;
      HDST_API
      void UnbindResources(int program,
                           HdSt_ResourceBinder const &binder) override;
      HDST_API
      void AddBindings(HdBindingRequestVector *customBindings) override;
      HDST_API
      HdSt_MaterialParamVector const& GetParams() const override;
  
      HDST_API
      NamedTextureHandleVector const & GetNamedTextureHandles() const override;
  
      /// Add a custom binding request for use when this shader executes.
      HDST_API
      void AddBufferBinding(HdBindingRequest const& req);
  
      /// Remove \p name from custom binding.
      HDST_API
      void RemoveBufferBinding(TfToken const &name);
  
      /// Clear all custom bindings associated with this shader.
      HDST_API
      void ClearBufferBindings();
  
      // Sets the textures and params such that the shader can access
      // the requested aovs with HdGet_AOVNAMEReadback().
      //
      // Needs to be called in task prepare or sync since it is
      // allocating texture handles.
      //
      HDST_API
      void UpdateAovInputTextures(
          HdRenderPassAovBindingVector const &aovInputBindings,
          HdRenderIndex * const renderIndex);
  
  private:
      TfToken _glslfxFile;
      std::unique_ptr<HioGlslfx> _glslfx;
      mutable size_t  _hash;
      mutable bool    _hashValid;
  
      TfHashMap<TfToken, HdBindingRequest, TfToken::HashFunctor> _customBuffers;
  
      NamedTextureHandleVector _namedTextureHandles;
  
      HdSt_MaterialParamVector _params;
  
      // No copying
      HdStRenderPassShader(const HdStRenderPassShader &)                     = delete;
      HdStRenderPassShader &operator =(const HdStRenderPassShader &)         = delete;
  
      HioGlslfx const * _GetGlslfx() const override;
  };
  
  
  PXR_NAMESPACE_CLOSE_SCOPE
  
  #endif // PXR_IMAGING_HD_ST_RENDER_PASS_SHADER_H
  