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# depthShader.cpp

    //-
    // ==========================================================================
    // Copyright 1995,2006,2008 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.
    // ==========================================================================
    //+

    #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/MArrayDataHandle.h>
    #include <maya/MFnNumericAttribute.h>
    #include <maya/MFnLightDataAttribute.h>
    #include <maya/MFloatVector.h>
    #include <maya/MFnPlugin.h>

    // Plugin Depth Shader Class //

    class depthShader : public MPxNode
    {
        public:
                          depthShader();
        virtual          ~depthShader();

        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 aColorNear;
        static MObject aColorFar;
        static MObject aNear;
        static MObject aFar;
        static MObject aPointCamera;

        // Output attributes
        static MObject aOutColor;
    };

    // static data
    MTypeId depthShader::id( 0x81002 );

    // Attributes
    MObject depthShader::aColorNear;
    MObject depthShader::aColorFar;
    MObject depthShader::aNear;
    MObject depthShader::aFar;
    MObject depthShader::aPointCamera;

    MObject depthShader::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));

    void depthShader::postConstructor( )
    {
        setMPSafe(true);
    }

    //
    // DESCRIPTION:
    depthShader::depthShader()
    {
    }

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

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

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

        // Create input attributes

        aColorNear = nAttr.createColor("color", "c");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0., 1., 0.));            // Green

        aColorFar = nAttr.createColor("colorFar", "cf");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0., 0., 1.));            // Blue

        aNear = nAttr.create("near", "n", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setSoftMax(1000.0f));

        aFar = nAttr.create("far", "f", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setSoftMax(1000.0f));
        CHECK_MSTATUS(nAttr.setDefault(2.0f));

        aPointCamera = nAttr.createPoint("pointCamera", "p");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setHidden(true));

        // Create output attributes
        aOutColor = nAttr.createColor("outColor", "oc");
        MAKE_OUTPUT(nAttr);

        CHECK_MSTATUS(addAttribute(aColorNear));
        CHECK_MSTATUS(addAttribute(aColorFar));
        CHECK_MSTATUS(addAttribute(aNear) );
        CHECK_MSTATUS(addAttribute(aFar));
        CHECK_MSTATUS(addAttribute(aPointCamera));
        CHECK_MSTATUS(addAttribute(aOutColor));

        CHECK_MSTATUS(attributeAffects(aColorNear, aOutColor));
        CHECK_MSTATUS(attributeAffects(aColorFar, aOutColor));
        CHECK_MSTATUS(attributeAffects(aNear, aOutColor));
        CHECK_MSTATUS(attributeAffects(aFar, aOutColor));
        CHECK_MSTATUS(attributeAffects(aPointCamera, aOutColor));

        return MS::kSuccess;
    }

    //
    // DESCRIPTION:
    MStatus depthShader::compute(
    const MPlug&      plug,
          MDataBlock& block )
    {
        // outColor or individial R, G, B channel
        if((plug != aOutColor) && (plug.parent() != aOutColor))
            return MS::kUnknownParameter;

        MFloatVector resultColor;

        // get sample surface shading parameters
        MFloatVector& pCamera = block.inputValue(aPointCamera).asFloatVector();
        MFloatVector& cNear   = block.inputValue(aColorNear).asFloatVector();
        MFloatVector& cFar    = block.inputValue(aColorFar).asFloatVector();
        float nearClip        = block.inputValue(aNear).asFloat();
        float farClip         = block.inputValue(aFar).asFloat();

        // pCamera.z is negative
        float ratio = (farClip + pCamera.z) / ( farClip - nearClip);
        resultColor = cNear * ratio + cFar*(1.f - ratio);

        // set ouput color attribute
        MDataHandle outColorHandle = block.outputValue( aOutColor );
        MFloatVector& outColor = outColorHandle.asFloatVector();
        outColor = resultColor;
        outColorHandle.setClean();

        return MS::kSuccess;
    }

    //
    // DESCRIPTION:
    MStatus initializePlugin( MObject obj )
    {
        const MString UserClassify( "shader/surface" );

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

        return MS::kSuccess;
    }

    //
    // DESCRIPTION:
    MStatus uninitializePlugin( MObject obj )
    {
        MFnPlugin plugin( obj );
        CHECK_MSTATUS( plugin.deregisterNode( depthShader::id ) );

        return MS::kSuccess;
    }