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_BPRIM_H
  #define PXR_IMAGING_HD_BPRIM_H
  
  #include "pxr/pxr.h"
  #include "pxr/imaging/hd/api.h"
  #include "pxr/imaging/hd/version.h"
  #include "pxr/imaging/hd/types.h"
  
  #include "pxr/usd/sdf/path.h"
  
  PXR_NAMESPACE_OPEN_SCOPE
  
  class HdSceneDelegate;
  class HdRenderParam;
  
  /// \class HdBprim
  ///
  /// Bprim (buffer prim) is a base class of managing a blob of data that is
  /// used to communicate between the scene delegate and render.
  ///
  /// Like other prim types (Rprim and Sprim), the Bprim communicates with the
  /// scene delegate got get buffer properties (e.g. the size of the buffer) as
  /// well as the contents of the buffer.
  ///
  /// Changes to the properties and contents are change tracked and updates
  /// are cached in the renderer.  The Render Delegate may choose to transform
  /// the data into a renderer specific form on download.
  ///
  /// BPrims are sync'ed first and thus, Bprims should not be
  /// Dependent on the state of any other prim.
  ///
  /// The most typical use of a Bprim would be a Texture.
  class HdBprim
  {
  public:
      HD_API
      HdBprim(SdfPath const & id);
      HD_API
      virtual ~HdBprim();
  
      /// Returns the identifier by which this buffer is known. This
      /// identifier is a common associative key used by the SceneDelegate,
      /// RenderIndex, and for binding to the buffer
      SdfPath const& GetId() const { return _id; }
  
      /// Synchronizes state from the delegate to this object.
      /// @param[in, out]  dirtyBits: On input specifies which state is
      ///                             is dirty and can be pulled from the scene
      ///                             delegate.
      ///                             On output specifies which bits are still
      ///                             dirty and were not cleaned by the sync. 
      ///                             
      virtual void Sync(HdSceneDelegate *sceneDelegate,
                        HdRenderParam   *renderParam,
                        HdDirtyBits     *dirtyBits) = 0;
  
      /// Finalizes object resources. This function might not delete resources,
      /// but it should deal with resource ownership so that the sprim is
      /// deletable.
      HD_API
      virtual void Finalize(HdRenderParam *renderParam);
  
      /// Returns the minimal set of dirty bits to place in the
      /// change tracker for use in the first sync of this prim.
      /// Typically this would be all dirty bits.
      virtual HdDirtyBits GetInitialDirtyBitsMask() const = 0;
  
  private:
      SdfPath _id;
  };
  
  
  PXR_NAMESPACE_CLOSE_SCOPE
  
  #endif  // PXR_IMAGING_HD_BPRIM_H
  