Arranging shaders into a pipeline

This code example implements a shader pipeline with class definitions for ShaderA, ShaderB, and ShaderC. The definitions follow the guidelines explained at the end of this example to ensure that the TShadingSample instance is valid throughout the following pipeline stages:

• ShaderA::ComputeShade modifies the input color and calls ShaderB::ComputeShade.
• ShaderB::ComputeShade modifies the input color and normal and calls ShaderC::ComputeShade.
• ShaderC::ComputeShade computes the output color.

  class ShaderA : public TShader
  {
      private:
          TShader * fShaderB;
  
      public:
          const TShader* GetChild(){ return fShaderB; };
          virtual Boolean NeedColor() { return TRUE; };
          virtual Boolean NeedNormal() { return GetChild()>NeedNormal(); };
  
          ComputeShade( TShadingSample& sSample, const TSceneBundle )
          {
              TRGBColor saveColor = *( sSample.fBaseColor );
              *( sSample.fBaseColor ) *= 2.;                  //Scale up by 2
              fShaderB>ComputeShade(TShadingSample& sSample, const TSceneBundle );
              *sSample.fBaseColor = saveColor;                //Restore base color.
          }
  };
  
  class ShaderB : public TShader
  {   private:
          TShader * fShaderC;
  
      public:
          const TShader* GetChild(){ return fShaderC; };
          virtual Boolean NeedColor() { return TRUE; };
          virtual Boolean NeedNormal() { return TRUE; };
  
          ComputeShade( TShadingSample& sSample, const TSceneBundle )
          {
              saveColor = *(sSample.fBaseColor );
              saveNormal = sSample.fShadingNormal;
              *( sSample.fBaseColor ) *= 3.;                  //Scale up by 3
              sSample.fShadingNormal *= 1.;                   //Reverse Normal
              fShaderC>ComputeShade(TShadingSample& sSample, const TSceneBundle );
              *sSample.fBaseColor = saveColor;                //Restore base color.
              *sSample.fShadingNormal = saveNormal;
          }
  };
  class ShaderC : public TShader
  {
          public:
              virtual Boolean NeedColor() { return TRUE };
              virtual Boolean NeedNormal() { return TRUE };
  
              ComputeShade( TShadingSample& sSample, const TSceneBundle )
              {
                  TRGBColor tmpCol = *(sSample.fBaseColor ) + TRGBColor( 
                                      sSample.fShadingNormal.fX,
                                      sSample.fShadingNormal.fY,
                                      sSample.fShadingNormal.fZ );
                  *( sSample.fResultantColor ) = tmpCol * ComputeDiffuse
                                          *( sSample.fShadingNormal, TSceneBundle ) );
              }
  };