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_HDX_SIMPLE_LIGHT_TASK_H
  #define PXR_IMAGING_HDX_SIMPLE_LIGHT_TASK_H
  
  #include "pxr/pxr.h"
  #include "pxr/imaging/hdx/api.h"
  #include "pxr/imaging/hdx/version.h"
  
  #include "pxr/imaging/hd/task.h"
  
  #include "pxr/imaging/glf/simpleLight.h"
  #include "pxr/imaging/glf/simpleMaterial.h"
  
  #include "pxr/imaging/cameraUtil/framing.h"
  
  #include "pxr/base/gf/vec3f.h"
  #include "pxr/base/tf/declarePtrs.h"
  
  #include <memory>
  
  PXR_NAMESPACE_OPEN_SCOPE
  
  class HdRenderIndex;
  class HdSceneDelegate;
  class HdCamera;
  
  using HdRenderPassSharedPtr = std::shared_ptr<class HdRenderPass>;
  using HdStSimpleLightingShaderSharedPtr =
      std::shared_ptr<class HdStSimpleLightingShader>;
  using HdxShadowMatrixComputationSharedPtr =
      std::shared_ptr<class HdxShadowMatrixComputation>;
  
  TF_DECLARE_REF_PTRS(GlfSimpleShadowArray);
  
  
  class HdxSimpleLightTask : public HdTask
  {
  public:
      HDX_API
      HdxSimpleLightTask(HdSceneDelegate* delegate, SdfPath const& id);
  
      HDX_API
      ~HdxSimpleLightTask() override;
  
      /// Sync the render pass resources
      HDX_API
      void Sync(HdSceneDelegate* delegate,
                HdTaskContext* ctx,
                HdDirtyBits* dirtyBits) override;
  
      /// Prepare the tasks resources
      HDX_API
      void Prepare(HdTaskContext* ctx,
                   HdRenderIndex* renderIndex) override;
  
      /// Execute render pass task
      HDX_API
      void Execute(HdTaskContext* ctx) override;
  
  private:
      std::vector<GfMatrix4d> _ComputeShadowMatrices(
          const HdCamera * camera,
          HdxShadowMatrixComputationSharedPtr const &computation) const;
  
      SdfPath _cameraId;
      std::map<TfToken, SdfPathVector> _lightIds;
      SdfPathVector _lightIncludePaths;
      SdfPathVector _lightExcludePaths;
      size_t _numLights;
  
      // Should be weak ptrs
      HdStSimpleLightingShaderSharedPtr _lightingShader;
      bool _enableShadows;
      GfVec4f _viewport;
      CameraUtilFraming _framing;
      std::pair<bool, CameraUtilConformWindowPolicy> _overrideWindowPolicy;
  
      // XXX: compatibility hack for passing some unit tests until we have
      //      more formal material plumbing.
      GlfSimpleMaterial _material;
      GfVec4f _sceneAmbient;
  
      // For now these are only valid for the lifetime of a single pass of
      // the render graph.  Maybe long-term these could be change-tracked.
      GlfSimpleLightVector _glfSimpleLights;
  
      HdBufferArrayRangeSharedPtr _lightingBar;
      HdBufferArrayRangeSharedPtr _lightSourcesBar;
      HdBufferArrayRangeSharedPtr _shadowsBar;
      HdBufferArrayRangeSharedPtr _materialBar;
  
      size_t _AppendLightsOfType(HdRenderIndex &renderIndex,
                                 TfTokenVector const &lightTypes,
                                 SdfPathVector const &lightIncludePaths,
                                 SdfPathVector const &lightExcludePaths,
                                 std::map<TfToken, SdfPathVector> *lights);
  
      HdxSimpleLightTask() = delete;
      HdxSimpleLightTask(const HdxSimpleLightTask &) = delete;
      HdxSimpleLightTask &operator =(const HdxSimpleLightTask &) = delete;
  };
  
  struct HdxSimpleLightTaskParams {
      HdxSimpleLightTaskParams()
          : cameraPath()
          , lightIncludePaths(1, SdfPath::AbsoluteRootPath())
          , lightExcludePaths()
          , enableShadows(false)
          , viewport(0.0f)
          , overrideWindowPolicy{false, CameraUtilFit}
          , material()
          , sceneAmbient(0) 
          {}
  
      SdfPath cameraPath;
      SdfPathVector lightIncludePaths;
      SdfPathVector lightExcludePaths;
      bool enableShadows;
      GfVec4f viewport;
      CameraUtilFraming framing;
      std::pair<bool, CameraUtilConformWindowPolicy> overrideWindowPolicy;
      
      // XXX: compatibility hack for passing some unit tests until we have
      //      more formal material plumbing.
      GlfSimpleMaterial material;
      GfVec4f sceneAmbient;
  };
  
  // VtValue requirements
  HDX_API
  std::ostream& operator<<(std::ostream& out, const HdxSimpleLightTaskParams& pv);
  HDX_API
  bool operator==(
      const HdxSimpleLightTaskParams& lhs, 
      const HdxSimpleLightTaskParams& rhs);
  HDX_API
  bool operator!=(
      const HdxSimpleLightTaskParams& lhs, 
      const HdxSimpleLightTaskParams& rhs);
  
  struct HdxShadowParams {
      HdxShadowParams()
          : shadowMatrix()
          , bias(0.0)
          , blur(0.0)
          , resolution(0)
          , enabled(false)
          {}
  
      HdxShadowMatrixComputationSharedPtr shadowMatrix;
      double bias;
      double blur;
      int resolution;
      bool enabled;
  };
  
  // VtValue requirements
  HDX_API
  std::ostream& operator<<(std::ostream& out, const HdxShadowParams& pv);
  HDX_API
  bool operator==(const HdxShadowParams& lhs, const HdxShadowParams& rhs);
  HDX_API
  bool operator!=(const HdxShadowParams& lhs, const HdxShadowParams& rhs);
  
  
  PXR_NAMESPACE_CLOSE_SCOPE
  
  #endif //PXR_IMAGING_HDX_SIMPLE_LIGHT_TASK_H
  