checkerShader.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.
// ==========================================================================
//+

// DESCRIPTION: A simple example of programmable checker texture.
//
// Inputs:
//
//  BiasU, BiasV: Control for the center of the checker.
//  Color1, Color2: the 2 colors for the checker.
//  UV: uv coordinate we're evaluating now.
//
// Output:
//
//  outColor: the result color.
//
// Need to enter the following commands before using:
//
//  shadingNode -asTexture checkerTexture;
//  shadingNode -asUtility place2dTexture;
//  connectAttr place2dTexture1.outUV checkerTexture1.uvCoord;

#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:
class CheckerNode : public MPxNode
{
        public:
                    CheckerNode();
    virtual         ~CheckerNode();

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

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

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

        private:

        // Input attributes
        static MObject aColor1;
        static MObject aColor2;
    static MObject aBias;
        static MObject aUVCoord;

        // Output attributes
        static MObject aOutColor;
        static MObject aOutAlpha;
};

// static data
const MTypeId CheckerNode::id( 0x81006 );

// Attributes
MObject  CheckerNode::aColor1;
MObject  CheckerNode::aColor2;
MObject  CheckerNode::aBias;
MObject  CheckerNode::aUVCoord;

MObject  CheckerNode::aOutColor;
MObject  CheckerNode::aOutAlpha;

#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 CheckerNode::postConstructor( )
{
        setMPSafe(true);
}


CheckerNode::CheckerNode()
{
}

CheckerNode::~CheckerNode()
{
}

// creates an instance of the node
void * CheckerNode::creator()
{
    return new CheckerNode();
}

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

    // Input attributes

        aColor1 = nAttr.createColor("color1", "c1");
        MAKE_INPUT(nAttr);
    CHECK_MSTATUS(nAttr.setDefault(0., .58824, .644) );         // Light blue

        aColor2 = nAttr.createColor("color2", "c2");
        MAKE_INPUT(nAttr);
    CHECK_MSTATUS(nAttr.setDefault(1., 1., 1.) );                       // White

    aBias = nAttr.create( "bias", "b", MFnNumericData::k2Float);
        MAKE_INPUT(nAttr);
    CHECK_MSTATUS(nAttr.setMin(0.0f, 0.0f) );
    CHECK_MSTATUS(nAttr.setMax(1.0f, 1.0f) );
    CHECK_MSTATUS(nAttr.setDefault(0.5f, 0.5f) );

        // Implicit shading network attributes

    MObject child1 = nAttr.create( "uCoord", "u", MFnNumericData::kFloat);
    MObject child2 = nAttr.create( "vCoord", "v", MFnNumericData::kFloat);
    aUVCoord = nAttr.create( "uvCoord","uv", child1, child2);
    MAKE_INPUT(nAttr);
    CHECK_MSTATUS(nAttr.setHidden(true) );

        // Output attributes

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

    aOutAlpha = nAttr.create( "outAlpha", "oa", MFnNumericData::kFloat);
        MAKE_OUTPUT(nAttr);

        // Add attributes to the node database.

    CHECK_MSTATUS(addAttribute(aColor1));
    CHECK_MSTATUS(addAttribute(aColor2));
    CHECK_MSTATUS(addAttribute(aBias));
    CHECK_MSTATUS(addAttribute(aUVCoord));
   
    CHECK_MSTATUS(addAttribute(aOutColor));
    CHECK_MSTATUS(addAttribute(aOutAlpha));

    // All input affect the output color and alpha
    CHECK_MSTATUS(attributeAffects (aColor1,  aOutColor));
    CHECK_MSTATUS(attributeAffects(aColor1, aOutAlpha));

    CHECK_MSTATUS(attributeAffects (aColor2,  aOutColor));
    CHECK_MSTATUS(attributeAffects(aColor2, aOutAlpha));

    CHECK_MSTATUS(attributeAffects(aBias, aOutColor));
    CHECK_MSTATUS(attributeAffects(aBias, aOutAlpha));

    CHECK_MSTATUS(attributeAffects (aUVCoord, aOutColor));
    CHECK_MSTATUS(attributeAffects(aUVCoord, aOutAlpha));

    return MS::kSuccess;
}


// DESCRIPTION:
// This function gets called by Maya to evaluate the texture.
//
// Get color1 and color2 from the input block.
// Get UV coordinates from the input block.
// Compute the color/alpha of our checker for a given UV coordinate.
// Put the result into the output plug.

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

    MFloatVector resultColor;
    float2 & uv = block.inputValue( aUVCoord ).asFloat2();
    float2 & bias = block.inputValue( aBias ).asFloat2();

    int count = 0;
        if (uv[0] - floorf(uv[0]) < bias[0]) count++;
        if (uv[1] - floorf(uv[1]) < bias[1]) count++;

    if (count & 1)
        resultColor = block.inputValue( aColor2 ).asFloatVector();
    else
        resultColor = block.inputValue( aColor1 ).asFloatVector();

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

    // Set ouput alpha attribute
        MDataHandle outAlphaHandle = block.outputValue( aOutAlpha );
        float& outAlpha = outAlphaHandle.asFloat();
        outAlpha = (count & 1) ? 1.f : 0.f;
        outAlphaHandle.setClean();

    return MS::kSuccess;
}

//
// DESCRIPTION:
MStatus initializePlugin( MObject obj )
{ 
   const MString UserClassify( "texture/2d" );

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

   return MS::kSuccess;
}

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

   return MS::kSuccess;
}