text: 
  //
  // This source file is part of appleseed.
  // Visit https://appleseedhq.net/ for additional information and resources.
  //
  // This software is released under the MIT license.
  //
  // Copyright (c) 2010-2013 Francois Beaune, Jupiter Jazz Limited
  // Copyright (c) 2014-2018 Francois Beaune, The appleseedhq Organization
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  //
  
  #pragma once
  
  // appleseed.renderer headers.
  #include "renderer/kernel/lighting/ilightingengine.h"
  #include "renderer/kernel/lighting/sppm/sppmparameters.h"
  
  // appleseed.foundation headers.
  #include "foundation/platform/compiler.h"
  
  // Forward declarations.
  namespace foundation    { class Dictionary; }
  namespace renderer      { class BackwardLightSampler; }
  namespace renderer      { class ForwardLightSampler; }
  namespace renderer      { class SPPMPassCallback; }
  
  namespace renderer
  {
  
  //
  // Stochastic Progressive Photon Mapping (SPPM) lighting engine factory.
  //
  
  class SPPMLightingEngineFactory
    : public ILightingEngineFactory
  {
    public:
      // Return parameters metadata.
      static foundation::Dictionary get_params_metadata();
  
      // Constructor.
      SPPMLightingEngineFactory(
          const SPPMPassCallback&         pass_callback,
          const ForwardLightSampler&      forward_light_sampler,
          const BackwardLightSampler&     backward_light_sampler,
          const SPPMParameters&           params);
  
      // Delete this instance.
      void release() override;
  
      // Return a new SPPM lighting engine instance.
      ILightingEngine* create() override;
  
    private:
      const SPPMParameters            m_params;
      const SPPMPassCallback&         m_pass_callback;
      const ForwardLightSampler&      m_forward_light_sampler;
      const BackwardLightSampler&     m_backward_light_sampler;
  };
  
  }   // namespace renderer
  