text: /*
    ==============================================================================
  
     This file is part of the JUCE library.
     Copyright (c) 2020 - Raw Material Software Limited
  
     JUCE is an open source library subject to commercial or open-source
     licensing.
  
     By using JUCE, you agree to the terms of both the JUCE 6 End-User License
     Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
  
     End User License Agreement: www.juce.com/juce-6-licence
     Privacy Policy: www.juce.com/juce-privacy-policy
  
     Or: You may also use this code under the terms of the GPL v3 (see
     www.gnu.org/licenses).
  
     JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
     EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
     DISCLAIMED.
  
    ==============================================================================
  */
  
  namespace juce
  {
  
  /** Creates a graphics context object that will render into the given OpenGL target. */
  std::unique_ptr<LowLevelGraphicsContext> createOpenGLGraphicsContext (OpenGLContext&, int width, int height);
  
  /** Creates a graphics context object that will render into the given OpenGL framebuffer. */
  std::unique_ptr<LowLevelGraphicsContext> createOpenGLGraphicsContext (OpenGLContext&, OpenGLFrameBuffer&);
  
  /** Creates a graphics context object that will render into the given OpenGL framebuffer,
      with the given size.
  */
  std::unique_ptr<LowLevelGraphicsContext> createOpenGLGraphicsContext (OpenGLContext&,
                                                                        unsigned int frameBufferID,
                                                                        int width, int height);
  
  
  //==============================================================================
  /**
      Used to create custom shaders for use with an openGL 2D rendering context.
  
      Given a GL-based rendering context, you can write a fragment shader that applies some
      kind of per-pixel effect.
  
      @tags{OpenGL}
  */
  struct JUCE_API  OpenGLGraphicsContextCustomShader
  {
      /** Creates a custom shader.
  
          The shader code will not be compiled until actually needed, so it's OK to call this
          constructor when no GL context is active.
  
          The code should be a normal fragment shader. As well as the usual GLSL variables, there is
          also an automatically declared varying vec2 called "pixelPos", which indicates the pixel
          position within the graphics context of the pixel being drawn. There is also a varying value
          "pixelAlpha", which indicates the alpha by which the pixel should be multiplied, so that the
          edges of any clip-region masks are anti-aliased correctly.
      */
      OpenGLGraphicsContextCustomShader (const String& fragmentShaderCode);
  
      /** Destructor. */
      ~OpenGLGraphicsContextCustomShader();
  
      /** Returns the program, if it has been linked and is active.
          This can be called when you're about to use fillRect, to set up any uniforms/textures that
          the program may require.
      */
      OpenGLShaderProgram* getProgram (LowLevelGraphicsContext&) const;
  
      /** Applies the shader to a rectangle within the graphics context. */
      void fillRect (LowLevelGraphicsContext&, Rectangle<int> area) const;
  
      /** Attempts to compile the program if necessary, and returns an error message if it fails. */
      Result checkCompilation (LowLevelGraphicsContext&);
  
      /** Returns the code that was used to create this object. */
      const String& getFragmentShaderCode() const noexcept           { return code; }
  
      /** Optional lambda that will be called when the shader is activated, to allow
          user code to do setup tasks.
      */
      std::function<void (OpenGLShaderProgram&)> onShaderActivated;
  
  private:
      String code, hashName;
  
      JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (OpenGLGraphicsContextCustomShader)
  };
  
  } // namespace juce
  