text: // ----------------------------------------------------------------------------
  // -                        Open3D: www.open3d.org                            -
  // ----------------------------------------------------------------------------
  // The MIT License (MIT)
  //
  // Copyright (c) 2018 www.open3d.org
  //
  // 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
  
  #include <vector>
  #include <Eigen/Core>
  #include <Open3D/Visualization/Shader/ShaderWrapper.h>
  
  namespace open3d {
  namespace visualization {
  
  namespace glsl {
  
  class Simple2DShader : public ShaderWrapper {
  public:
      ~Simple2DShader() override { Release(); }
  
  protected:
      Simple2DShader(const std::string &name) : ShaderWrapper(name) { Compile(); }
  
  protected:
      bool Compile() final;
      void Release() final;
      bool BindGeometry(const geometry::Geometry &geometry,
                        const RenderOption &option,
                        const ViewControl &view) final;
      bool RenderGeometry(const geometry::Geometry &geometry,
                          const RenderOption &option,
                          const ViewControl &view) final;
      void UnbindGeometry() final;
  
  protected:
      virtual bool PrepareRendering(const geometry::Geometry &geometry,
                                    const RenderOption &option,
                                    const ViewControl &view) = 0;
      virtual bool PrepareBinding(const geometry::Geometry &geometry,
                                  const RenderOption &option,
                                  const ViewControl &view,
                                  std::vector<Eigen::Vector3f> &points,
                                  std::vector<Eigen::Vector3f> &colors) = 0;
  
  protected:
      GLuint vertex_position_;
      GLuint vertex_position_buffer_;
      GLuint vertex_color_;
      GLuint vertex_color_buffer_;
  };
  
  class Simple2DShaderForSelectionPolygon : public Simple2DShader {
  public:
      Simple2DShaderForSelectionPolygon()
          : Simple2DShader("Simple2DShaderForSelectionPolygon") {}
  
  protected:
      bool PrepareRendering(const geometry::Geometry &geometry,
                            const RenderOption &option,
                            const ViewControl &view) final;
      bool PrepareBinding(const geometry::Geometry &geometry,
                          const RenderOption &option,
                          const ViewControl &view,
                          std::vector<Eigen::Vector3f> &points,
                          std::vector<Eigen::Vector3f> &colors) final;
  };
  
  }  // namespace glsl
  
  }  // namespace visualization
  }  // namespace open3d
  