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# gammaShader.cpp

    //-
    // ===========================================================================
    // Copyright 2012 Autodesk, Inc. All rights reserved.
    //
    // Use of this software is subject to the terms of the Autodesk license
    // agreement provided at the time of installation or download, or which
    // otherwise accompanies this software in either electronic or hard copy form.
    // ===========================================================================
    //+

    //
    // DESCRIPTION:  Gamma correction utility node
    //

    #include <math.h>

    #include <maya/MPxNode.h>
    #include <maya/MIOStream.h>
    #include <maya/MString.h>
    #include <maya/MTypeId.h>
    #include <maya/MPlug.h>
    #include <maya/MDataBlock.h>
    #include <maya/MDataHandle.h>
    #include <maya/MFnNumericAttribute.h>
    #include <maya/MFloatVector.h>
    #include <maya/MFnPlugin.h>
    #include <maya/MDrawRegistry.h>
    #include <maya/MPxShadingNodeOverride.h>
    #include <maya/MViewport2Renderer.h>
    #include <maya/MFragmentManager.h>

    //
    // Node declaration
    class Gamma:public MPxNode
    {
        public:
                        Gamma();
        virtual         ~Gamma();

        virtual MStatus compute( const MPlug&, MDataBlock& );
        virtual void    postConstructor();

        static void *  creator();
        static MStatus initialize();

        // Id tag for use with binary file format
        static MTypeId id;

        private:

        // Input attributes
        static MObject aColor;                  // Input color
        static MObject aGamma;                  // R, G, B correction

        // Output attributes
        static MObject aOutColor;
    };

    //
    // Override declaration
    class GammaOverride : public MHWRender::MPxShadingNodeOverride
    {
    public:
        static MHWRender::MPxShadingNodeOverride* creator(const MObject& obj);

        virtual ~GammaOverride();

        virtual MHWRender::DrawAPI supportedDrawAPIs() const;

        virtual MString fragmentName() const;

    private:
        GammaOverride(const MObject& obj);

        MString fFragmentName;
    };

    //
    // Node definition
    MTypeId Gamma::id( 0x81009 );

    // Attributes
    MObject Gamma::aColor;
    MObject Gamma::aGamma;
    MObject Gamma::aOutColor;

    #define MAKE_INPUT(attr)                                \
     CHECK_MSTATUS ( attr.setKeyable(true) );               \
     CHECK_MSTATUS ( attr.setStorable(true) );              \
     CHECK_MSTATUS ( attr.setReadable(true) );              \
     CHECK_MSTATUS ( attr.setWritable(true) );

    #define MAKE_OUTPUT(attr)                               \
      CHECK_MSTATUS ( attr.setKeyable(false) );             \
      CHECK_MSTATUS ( attr.setStorable(false) );            \
      CHECK_MSTATUS ( attr.setReadable(true) );             \
      CHECK_MSTATUS ( attr.setWritable(false) );

    //
    // DESCRIPTION:
    void Gamma::postConstructor( )
    {
        setMPSafe(true);
    }

    //
    // DESCRIPTION:
    Gamma::Gamma()
    {
    }

    //
    // DESCRIPTION:
    Gamma::~Gamma()
    {
    }

    //
    // DESCRIPTION:
    void *Gamma::creator()
    {
        return new Gamma();
    }

    //
    // DESCRIPTION:
    MStatus Gamma::initialize()
    {
        MFnNumericAttribute     nAttr;

        // Input attributes

        aColor = nAttr.createColor( "color", "c" );
        MAKE_INPUT(nAttr);

        aGamma = nAttr.createPoint( "gamma", "g" );
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS ( nAttr.setDefault(1.f, 1.f, 1.f) );

        // Output attributes

        aOutColor= nAttr.createColor( "outColor", "oc" );
        MAKE_OUTPUT(nAttr);

        //  Add attributes to the node database.
        CHECK_MSTATUS ( addAttribute(aColor) );
        CHECK_MSTATUS ( addAttribute(aGamma) );
        CHECK_MSTATUS ( addAttribute(aOutColor) );

        // All input affect the output color
        CHECK_MSTATUS ( attributeAffects( aColor, aOutColor ));
        CHECK_MSTATUS ( attributeAffects( aGamma, aOutColor ));

        return MS::kSuccess;
    }

    //
    // DESCRIPTION:
    MStatus Gamma::compute(const MPlug &plug, MDataBlock &block)
    {
        if ((plug != aOutColor) && (plug.parent() != aOutColor))
            return MS::kUnknownParameter;

        MFloatVector & icol = block.inputValue( aColor ).asFloatVector();
        MFloatVector & igam = block.inputValue( aGamma ).asFloatVector();

        MDataHandle och = block.outputValue( aOutColor );
        MFloatVector & ocol = och.asFloatVector();
        ocol[0]= powf(icol[0], 1.f/igam[0]);
        ocol[1]= powf(icol[1], 1.f/igam[1]);
        ocol[2]= powf(icol[2], 1.f/igam[2]);
        och.setClean();

        return MS::kSuccess;
    }

    //
    // Override definition
    MHWRender::MPxShadingNodeOverride* GammaOverride::creator(
        const MObject& obj)
    {
        return new GammaOverride(obj);
    }

    GammaOverride::GammaOverride(const MObject& obj)
    : MPxShadingNodeOverride(obj)
    , fFragmentName("")
    {
        // Define fragments needed for VP2 version of shader, this could also be
        // defined in a separate XML file
        //
        // Define the input and output parameter names to match the input and
        // output attribute names so that the values are automatically populated
        // on the shader.
        static const MString sFragmentName("gammaShaderPluginFragment");
        static const char* sFragmentBody =
            "<fragment uiName=\"gammaShaderPluginFragment\" name=\"gammaShaderPluginFragment\" type=\"plumbing\" class=\"ShadeFragment\" version=\"1.0\">"
            "   <description><![CDATA[Gamma utility fragment]]></description>"
            "   <properties>"
            "       <float3 name=\"color\" />"
            "       <float3 name=\"gamma\" />"
            "   </properties>"
            "   <values>"
            "       <float3 name=\"color\" value=\"0.5,0.5,0.5\" />"
            "       <float3 name=\"gamma\" value=\"1.0,1.0,1.0\" />"
            "   </values>"
            "   <outputs>"
            "       <float3 name=\"outColor\" />"
            "   </outputs>"
            "   <implementation>"
            "   <implementation render=\"OGSRenderer\" language=\"Cg\" lang_version=\"2.1\">"
            "       <function_name val=\"gammaShaderPluginFragment\" />"
            "       <source><![CDATA["
            "float3 gammaShaderPluginFragment(float3 icol, float3 igam) \n"
            "{ \n"
            "   float3 result; \n"
            "   result.r = pow(icol.r, 1.0f/igam.r); \n"
            "   result.g = pow(icol.g, 1.0f/igam.g); \n"
            "   result.b = pow(icol.b, 1.0f/igam.b); \n"
            "   return result; \n"
            "} \n]]>"
            "       </source>"
            "   </implementation>"
            "   <implementation render=\"OGSRenderer\" language=\"HLSL\" lang_version=\"11.0\">"
            "       <function_name val=\"gammaShaderPluginFragment\" />"
            "       <source><![CDATA["
            "float3 gammaShaderPluginFragment(float3 icol, float3 igam) \n"
            "{ \n"
            "   float3 result; \n"
            "   result.r = pow(icol.r, 1.0f/igam.r); \n"
            "   result.g = pow(icol.g, 1.0f/igam.g); \n"
            "   result.b = pow(icol.b, 1.0f/igam.b); \n"
            "   return result; \n"
            "} \n]]>"
            "       </source>"
            "   </implementation>"
            "   </implementation>"
            "</fragment>";

        // Register fragments with the manager if needed
        MHWRender::MRenderer* theRenderer = MHWRender::MRenderer::theRenderer();
        if (theRenderer)
        {
            MHWRender::MFragmentManager* fragmentMgr =
                theRenderer->getFragmentManager();
            if (fragmentMgr)
            {
                // Add fragments if needed
                bool fragAdded = fragmentMgr->hasFragment(sFragmentName);
                if (!fragAdded)
                {
                    fragAdded = (sFragmentName == fragmentMgr->addShadeFragmentFromBuffer(sFragmentBody, false));
                }

                // Use the fragment on successful add
                if (fragAdded)
                {
                    fFragmentName = sFragmentName;
                }
            }
        }
    }

    GammaOverride::~GammaOverride()
    {
    }

    MHWRender::DrawAPI GammaOverride::supportedDrawAPIs() const
    {
        return MHWRender::kOpenGL | MHWRender::kDirectX11;
    }

    MString GammaOverride::fragmentName() const
    {
        return fFragmentName;
    }

    //
    // Plugin setup
    static const MString sRegistrantId("gammaShaderPlugin");

    MStatus initializePlugin( MObject obj )
    {
       const MString UserClassify( "utility/color:drawdb/shader/operation/gammaNode" );

       MFnPlugin plugin( obj, PLUGIN_COMPANY, "4.5", "Any");
       CHECK_MSTATUS ( plugin.registerNode( "gammaNode", Gamma::id,
                             Gamma::creator, Gamma::initialize,
                             MPxNode::kDependNode, &UserClassify ) );

        CHECK_MSTATUS(
            MHWRender::MDrawRegistry::registerShadingNodeOverrideCreator(
                "drawdb/shader/operation/gammaNode",
                sRegistrantId,
                GammaOverride::creator));

       return MS::kSuccess;
    }

    MStatus uninitializePlugin( MObject obj )
    {
       MFnPlugin plugin( obj );
       CHECK_MSTATUS ( plugin.deregisterNode( Gamma::id ) );

        CHECK_MSTATUS(
            MHWRender::MDrawRegistry::deregisterShadingNodeOverrideCreator(
                "drawdb/shader/operation/gammaNode",
                sRegistrantId));

       return MS::kSuccess;
    }