displacementShader/displacementShader.cpp

#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>

// DESCRIPTION: 
//  Produces dependency graph node DispNodeExample 

//  This node is an example of a displacement shader.

//  The inputs for this node are input color and an input multiplier.

//  The output attribute for this node is called "displacement". 
//  To use this shader, create a DispNodeExample node and connect its output to the "displacementShader" input of a Shading Group. 
//


class DispNode : public MPxNode
{
    public:
                  DispNode();
         ~DispNode() override;

    MStatus compute( const MPlug&, MDataBlock& ) override;
    SchedulingType schedulingType() const override { return SchedulingType::kParallel; }

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

    static  MTypeId id;

    private:

    static MObject aColor;
    static MObject aInputValue;
    static MObject aOutColor;
    static MObject aOutTransparency;
    static MObject aOutDisplacement;
};

MTypeId DispNode::id( 0x81011 );

MObject DispNode::aColor;
MObject DispNode::aInputValue;
MObject DispNode::aOutColor;
MObject DispNode::aOutTransparency;
MObject DispNode::aOutDisplacement;

//
// DESCRIPTION:
DispNode::DispNode()
{
}

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

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



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

    // Inputs
    aColor = nAttr.createColor( "color", "c" );
    CHECK_MSTATUS(nAttr.setKeyable(true));
    CHECK_MSTATUS(nAttr.setStorable(true));
    CHECK_MSTATUS(nAttr.setDefault(1.0f, 1.0f, 1.0f));

    aInputValue = nAttr.create( "factor", "f", MFnNumericData::kFloat);
    CHECK_MSTATUS(nAttr.setKeyable(true));
    CHECK_MSTATUS(nAttr.setStorable(true));
    CHECK_MSTATUS(nAttr.setDefault(1.0f));

    // Outputs

    aOutColor  = nAttr.createColor( "outColor", "oc" );
    CHECK_MSTATUS(nAttr.setStorable(false));
    CHECK_MSTATUS(nAttr.setHidden(false));
    CHECK_MSTATUS(nAttr.setReadable(true));
    CHECK_MSTATUS(nAttr.setWritable(false));

    aOutTransparency  = nAttr.createColor( "outTransparency", "ot" );
    CHECK_MSTATUS(nAttr.setStorable(false));
    CHECK_MSTATUS(nAttr.setHidden(false));
    CHECK_MSTATUS(nAttr.setReadable(true));
    CHECK_MSTATUS(nAttr.setWritable(false));

    aOutDisplacement = nAttr.create( "displacement", "od", 
                                     MFnNumericData::kFloat);
    CHECK_MSTATUS(nAttr.setStorable(false));
    CHECK_MSTATUS(nAttr.setHidden(false));
    CHECK_MSTATUS(nAttr.setReadable(true));
    CHECK_MSTATUS(nAttr.setWritable(false));


    CHECK_MSTATUS(addAttribute(aColor));
    CHECK_MSTATUS(addAttribute(aInputValue));
    CHECK_MSTATUS(addAttribute(aOutColor));
    CHECK_MSTATUS(addAttribute(aOutTransparency));
    CHECK_MSTATUS(addAttribute(aOutDisplacement));

    CHECK_MSTATUS(attributeAffects (aColor, aOutColor));
    CHECK_MSTATUS(attributeAffects (aColor, aOutDisplacement));

    return MS::kSuccess;
}

//
// DESCRIPTION:
MStatus DispNode::compute(
const MPlug&      plug,
      MDataBlock& block ) 
{ 
    if ((plug == aOutColor) || (plug.parent() == aOutColor) ||
        (plug == aOutDisplacement))
    {
        MFloatVector resultColor(0.0,0.0,0.0);

        MFloatVector&  InputColor = block.inputValue( aColor ).asFloatVector();
        float MultValue = block.inputValue( aInputValue ).asFloat();

        resultColor = InputColor;

        float scalar = resultColor[0] + resultColor[1] + resultColor[2];
        if (scalar != 0.0) {
            scalar /= 3.0;
            scalar *= MultValue;
        }

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

        MDataHandle outDispHandle = block.outputValue( aOutDisplacement );
        float& outDisp = outDispHandle.asFloat();
        outDisp = scalar;
        outDispHandle.setClean( );
    }
    else if ((plug == aOutTransparency) || (plug.parent() == aOutTransparency))
    {
        // set output transparency to be opaque
        MFloatVector transparency(0.0,0.0,0.0);
        MDataHandle outTransHandle = block.outputValue( aOutTransparency );
        MFloatVector& outTrans = outTransHandle.asFloatVector();
        outTrans = transparency;
        outTransHandle.setClean( );
    }
    else
        return MS::kUnknownParameter;

    return MS::kSuccess;
}

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

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

   return MS::kSuccess;
}

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

   return MS::kSuccess;
}