MAYA-API-REF/cpp_ref/onb_shader_2onb_shader_8cpp-example.html

//

// Example Plugin: onbShader.cpp

//

// Produces dependency graph node onbShader

// This node is an example of how to build a dependency node as a surface

// shader in Maya. The inputs for this node are many, and can be found in

// the Maya UI on the Attribute Editor for the node. The output attributes for

// the node are outColor and outTransparency. To use this shader, create an

// onbShader with Shading Group or connect the outputs to a Shading Group's

// "surfaceShader" attribute.

//

// The actual shader implemented here uses a simplified Oren-Nayar diffuse

// model based on:

//      Engel, Wolfgang et al.: Programming Vertex, Geometry, and Pixel Shaders

//      http://content.gpwiki.org/index.php/D3DBook:(Lighting)_Oren-Nayar

// The diffuse computation is combined with Blinn specular highlighting.

//

// In addition to implementing the dependency node, this plug-in also shows a

// complete implementation of a surface shader for VP2. Unlike lambertShader or

// phongShader this sample does not re-use Maya's built in fragments. All

// fragment code is defined by the plug-in. See onbShaderOverride.cpp for

// details.

//


#include <maya/MPxNode.h>

#include <maya/MFnPlugin.h>

#include <maya/MIOStream.h>

#include <maya/MDrawRegistry.h>

#include <maya/MFnNumericAttribute.h>

#include <maya/MFnLightDataAttribute.h>

#include <algorithm> // for min/max


#include "onbShaderOverride.h"


class OnbShader : public MPxNode

{

public:

    static void* creator();

    static MStatus initialize();

    static MTypeId id;

    static MString nodeName;

    static MString drawDbClassification;

    static MString classification;


    OnbShader();

    ~OnbShader() override;


    MStatus compute(const MPlug&, MDataBlock&) override;

    SchedulingType schedulingType() const override { return SchedulingType::kParallel; }


private:

    // Output attributes

    static MObject aOutColor;

    static MObject aOutTransparency;


    // Shader attributes

    static MObject aColor;

    static MObject aRoughness;

    static MObject aTransparency;

    static MObject aAmbientColor;

    static MObject aIncandescence;

    static MObject aSpecularColor;

    static MObject aEccentricity;

    static MObject aSpecularRollOff;

    static MObject aNormalCamera;


    // Light attributes for compute()

    static MObject aRayDirection;

    static MObject aLightDirection;

    static MObject aLightIntensity;

    static MObject aLightAmbient;

    static MObject aLightDiffuse;

    static MObject aLightSpecular;

    static MObject aLightShadowFraction;

    static MObject aPreShadowIntensity;

    static MObject aLightBlindData;

    static MObject aLightData;

};


// Static data

MTypeId OnbShader::id(0x00080FFF);

MString OnbShader::nodeName("onbShader");

MString OnbShader::drawDbClassification("drawdb/shader/surface/onbShader");

MString OnbShader::classification("shader/surface:" + drawDbClassification);


// Attributes

MObject OnbShader::aOutColor;

MObject OnbShader::aOutTransparency;

MObject OnbShader::aColor;

MObject OnbShader::aRoughness;

MObject OnbShader::aTransparency;

MObject OnbShader::aAmbientColor;

MObject OnbShader::aIncandescence;

MObject OnbShader::aSpecularColor;

MObject OnbShader::aEccentricity;

MObject OnbShader::aSpecularRollOff;

MObject OnbShader::aNormalCamera;

MObject OnbShader::aRayDirection;

MObject OnbShader::aLightDirection;

MObject OnbShader::aLightIntensity;

MObject OnbShader::aLightAmbient;

MObject OnbShader::aLightDiffuse;

MObject OnbShader::aLightSpecular;

MObject OnbShader::aLightShadowFraction;

MObject OnbShader::aPreShadowIntensity;

MObject OnbShader::aLightBlindData;

MObject OnbShader::aLightData;


// Helper pre-processor defines

#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));


// Methods

OnbShader::OnbShader()

{

}


OnbShader::~OnbShader()

{

}


void* OnbShader::creator()

{

    return new OnbShader();

}


MStatus OnbShader::initialize()

{

    MFnNumericAttribute nAttr;

    MFnLightDataAttribute lAttr;


    // Outputs

    MObject outcR = nAttr.create("outColorR", "ocr", MFnNumericData::kFloat, 0.0);

    MObject outcG = nAttr.create("outColorG", "ocg", MFnNumericData::kFloat, 0.0);

    MObject outcB = nAttr.create("outColorB", "ocb", MFnNumericData::kFloat, 0.0);

    aOutColor = nAttr.create("outColor", "oc", outcR, outcG, outcB);

    MAKE_OUTPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    MObject outtR = nAttr.create("outTransparencyR", "otr", MFnNumericData::kFloat, 0.0);

    MObject outtG = nAttr.create("outTransparencyG", "otg", MFnNumericData::kFloat, 0.0);

    MObject outtB = nAttr.create("outTransparencyB", "otb", MFnNumericData::kFloat, 0.0);

    aOutTransparency = nAttr.create("outTransparency", "ot", outtR, outtG, outtB);

    MAKE_OUTPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    // Inputs

    MObject cR = nAttr.create("colorR", "cr", MFnNumericData::kFloat, 0.5);

    MObject cG = nAttr.create("colorG", "cg", MFnNumericData::kFloat, 0.5);

    MObject cB = nAttr.create("colorB", "cb", MFnNumericData::kFloat, 0.5);

    aColor = nAttr.create("color", "c", cR, cG, cB);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    aRoughness = nAttr.create("roughness", "r", MFnNumericData::kFloat);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setMin(0.0f));

    CHECK_MSTATUS(nAttr.setMax(1.0f));

    CHECK_MSTATUS(nAttr.setDefault(0.3f));


    MObject tR = nAttr.create("transparencyR", "itr", MFnNumericData::kFloat, 0.0);

    MObject tG = nAttr.create("transparencyG", "itg", MFnNumericData::kFloat, 0.0);

    MObject tB = nAttr.create("transparencyB", "itb", MFnNumericData::kFloat, 0.0);

    aTransparency = nAttr.create("transparency", "it", tR, tG, tB);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    MObject aR = nAttr.create("ambientColorR", "acr", MFnNumericData::kFloat, 0.0);

    MObject aG = nAttr.create("ambientColorG", "acg", MFnNumericData::kFloat, 0.0);

    MObject aB = nAttr.create("ambientColorB", "acb", MFnNumericData::kFloat, 0.0);

    aAmbientColor = nAttr.create("ambientColor", "ambc", aR, aG, aB);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    MObject iR = nAttr.create("incandescenceR", "ir", MFnNumericData::kFloat, 0.0);

    MObject iG = nAttr.create("incandescenceG", "ig", MFnNumericData::kFloat, 0.0);

    MObject iB = nAttr.create("incandescenceB", "ib", MFnNumericData::kFloat, 0.0);

    aIncandescence = nAttr.create("incandescence", "ic", iR, iG, iB);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    MObject sR = nAttr.create("specularColorR", "sr", MFnNumericData::kFloat, 1.0);

    MObject sG = nAttr.create("specularColorG", "sg", MFnNumericData::kFloat, 1.0);

    MObject sB = nAttr.create("specularColorB", "sb", MFnNumericData::kFloat, 1.0);

    aSpecularColor = nAttr.create("specularColor", "sc", sR, sG, sB);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setUsedAsColor(true));


    aEccentricity = nAttr.create("eccentricity", "ecc", MFnNumericData::kFloat);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setMin(0.0f));

    CHECK_MSTATUS(nAttr.setMax(1.0f));

    CHECK_MSTATUS(nAttr.setDefault(0.1f));


    aSpecularRollOff = nAttr.create("specularRollOff", "sro", MFnNumericData::kFloat);

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setMin(0.0f));

    CHECK_MSTATUS(nAttr.setMax(1.0f));

    CHECK_MSTATUS(nAttr.setDefault(0.7f));


    aNormalCamera = nAttr.createPoint("normalCamera", "n");

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setDefault(1.0f, 1.0f, 1.0f));


    // Attributes for compute()

    aRayDirection = nAttr.createPoint("rayDirection", "rd");

    MAKE_INPUT(nAttr);

    CHECK_MSTATUS(nAttr.setHidden(true));


    aLightDirection = nAttr.createPoint("lightDirection", "ld");

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));

    CHECK_MSTATUS(nAttr.setDefault(1.0f, 1.0f, 1.0f));


    aLightIntensity = nAttr.createColor("lightIntensity", "li");

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));

    CHECK_MSTATUS(nAttr.setDefault(1.0f, 1.0f, 1.0f));


    aLightAmbient = nAttr.create("lightAmbient", "la", MFnNumericData::kBoolean);

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));


    aLightDiffuse = nAttr.create("lightDiffuse", "ldf", MFnNumericData::kBoolean);

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));


    aLightSpecular = nAttr.create("lightSpecular", "ls", MFnNumericData::kBoolean);

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));


    aLightShadowFraction = nAttr.create("lightShadowFraction", "lsf", MFnNumericData::kFloat);

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));


    aPreShadowIntensity = nAttr.create("preShadowIntensity", "psi", MFnNumericData::kFloat);

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));


    aLightBlindData = nAttr.createAddr("lightBlindData", "lbld");

    CHECK_MSTATUS(nAttr.setStorable(false));

    CHECK_MSTATUS(nAttr.setHidden(true));

    CHECK_MSTATUS(nAttr.setReadable(true));

    CHECK_MSTATUS(nAttr.setWritable(false));


    aLightData = lAttr.create("lightDataArray", "ltd",

        aLightDirection,

        aLightIntensity,

        aLightAmbient,

        aLightDiffuse,

        aLightSpecular,

        aLightShadowFraction,

        aPreShadowIntensity,

        aLightBlindData);

    CHECK_MSTATUS(lAttr.setArray(true));

    CHECK_MSTATUS(lAttr.setStorable(false));

    CHECK_MSTATUS(lAttr.setHidden(true));

    CHECK_MSTATUS(lAttr.setDefault(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, true, true, false, 0.0f, 1.0f, NULL));


    // Add Attributes

    CHECK_MSTATUS(addAttribute(aOutColor));

    CHECK_MSTATUS(addAttribute(aOutTransparency));

    CHECK_MSTATUS(addAttribute(aColor));

    CHECK_MSTATUS(addAttribute(aRoughness));

    CHECK_MSTATUS(addAttribute(aTransparency));

    CHECK_MSTATUS(addAttribute(aAmbientColor));

    CHECK_MSTATUS(addAttribute(aIncandescence));

    CHECK_MSTATUS(addAttribute(aSpecularColor));

    CHECK_MSTATUS(addAttribute(aEccentricity));

    CHECK_MSTATUS(addAttribute(aSpecularRollOff));

    CHECK_MSTATUS(addAttribute(aNormalCamera));

    CHECK_MSTATUS(addAttribute(aRayDirection));

    CHECK_MSTATUS(addAttribute(aLightData));


    // Attribute affects relationships

    CHECK_MSTATUS(attributeAffects(aColor, aOutColor));

    CHECK_MSTATUS(attributeAffects(aColor, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aRoughness, aOutColor));

    CHECK_MSTATUS(attributeAffects(aRoughness, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aTransparency, aOutColor));

    CHECK_MSTATUS(attributeAffects(aTransparency, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aAmbientColor, aOutColor));

    CHECK_MSTATUS(attributeAffects(aAmbientColor, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aIncandescence, aOutColor));

    CHECK_MSTATUS(attributeAffects(aIncandescence, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aSpecularColor, aOutColor));

    CHECK_MSTATUS(attributeAffects(aSpecularColor, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aEccentricity, aOutColor));

    CHECK_MSTATUS(attributeAffects(aEccentricity, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aNormalCamera, aOutColor));

    CHECK_MSTATUS(attributeAffects(aNormalCamera, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aRayDirection, aOutColor));

    CHECK_MSTATUS(attributeAffects(aRayDirection, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aSpecularRollOff, aOutColor));

    CHECK_MSTATUS(attributeAffects(aSpecularRollOff, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightDirection, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightDirection, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightIntensity, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightIntensity, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightAmbient, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightAmbient, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightDiffuse, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightDiffuse, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightSpecular, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightSpecular, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightShadowFraction, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightShadowFraction, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aPreShadowIntensity, aOutColor));

    CHECK_MSTATUS(attributeAffects(aPreShadowIntensity, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightBlindData, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightBlindData, aOutTransparency));

    CHECK_MSTATUS(attributeAffects(aLightData, aOutColor));

    CHECK_MSTATUS(attributeAffects(aLightData, aOutTransparency));


    return MS::kSuccess;

}


MStatus OnbShader::compute(const MPlug& plug, MDataBlock& block)

{

    // Sanity check

    if (plug != aOutColor && plug.parent() != aOutColor &&

        plug != aOutTransparency && plug.parent() != aOutTransparency)

    {

        return MS::kUnknownParameter;

    }


    // Note that this currently only implements the diffuse portion of the

    // shader and ignores specular. The diffuse portion is the Oren-Nayar

    // computation from:

    //   Engel, Wolfgang et al. Programming Vertex, Geometry, and Pixel Shaders

    //   http://content.gpwiki.org/index.php/D3DBook:(Lighting)_Oren-Nayar

    // Further extensions could be added to this compute method to include

    // the intended Blinn specular component as well as ambient and

    // incandescence components.

    // See the VP2 fragment-based implementation in onbShaderOverride for the

    // full shader.

    MStatus status;

    MFloatVector resultColor(0.0f, 0.0f, 0.0f);

    MFloatVector resultTransparency(0.0f, 0.0f, 0.0f);


    // Get surface shading parameters from input block

    const MFloatVector& surfaceColor =

        block.inputValue(aColor, &status).asFloatVector();

    CHECK_MSTATUS(status);

    const float roughness = block.inputValue(aRoughness, &status).asFloat();

    CHECK_MSTATUS(status);

    const MFloatVector& transparency =

        block.inputValue(aTransparency, &status).asFloatVector();

    CHECK_MSTATUS(status);

    const MFloatVector& surfaceNormal =

        block.inputValue(aNormalCamera, &status).asFloatVector();

    CHECK_MSTATUS(status);

    const MFloatVector& rayDirection =

        block.inputValue(aRayDirection).asFloatVector();

    const MFloatVector viewDirection = -rayDirection;


    // Pre-compute some values that do not vary with lights

    const float NV = viewDirection*surfaceNormal;

    const float acosNV = acosf(NV);

    const float roughnessSq = roughness*roughness;

    const float A = 1.0f - 0.5f*(roughnessSq/(roughnessSq + 0.57f));

    const float B = 0.45f*(roughnessSq/(roughnessSq + 0.09f));


    // Get light list

    MArrayDataHandle lightData = block.inputArrayValue(aLightData, &status);

    CHECK_MSTATUS(status);

    const int numLights = lightData.elementCount(&status);

    CHECK_MSTATUS(status);


    // Iterate through light list and get ambient/diffuse values

    for (int count=1; count<=numLights; count++)

    {

        // Get the current light

        MDataHandle currentLight = lightData.inputValue(&status);

        CHECK_MSTATUS(status);


        // Find diffuse component

        if (currentLight.child(aLightDiffuse).asBool())

        {

            // Get the intensity and direction of that light

            const MFloatVector& lightIntensity =

                currentLight.child(aLightIntensity).asFloatVector();

            const MFloatVector& lightDirection =

                currentLight.child(aLightDirection).asFloatVector();


            // Compute the diffuse factor

            const float NL = lightDirection*surfaceNormal;

            const float acosNL = acosf(NL);

            const float alpha = std::max(acosNV, acosNL);

            const float beta = std::min(acosNV, acosNL);

            const float gamma =

                (viewDirection - (surfaceNormal*NV)) *

                (lightDirection - (surfaceNormal*NL));

            const float C = sinf(alpha)*tanf(beta);

            const float factor =

                std::max(0.0f, NL)*(A + B*std::max(0.0f, gamma)*C);


            // Add to result color

            resultColor += lightIntensity*factor;

        }


        // Advance to the next light.

        if (count < numLights)

        {

            status = lightData.next();

            CHECK_MSTATUS(status);

        }

    }


    // Factor incident light with surface color

    resultColor[0] = resultColor[0]*surfaceColor[0];

    resultColor[1] = resultColor[1]*surfaceColor[1];

    resultColor[2] = resultColor[2]*surfaceColor[2];


    // Set ouput color attribute

    if (plug == aOutColor || plug.parent() == aOutColor)

    {

        // Get the handle to the attribute

        MDataHandle outColorHandle = block.outputValue(aOutColor, &status);

        CHECK_MSTATUS(status);

        MFloatVector& outColor = outColorHandle.asFloatVector();


        // Set the result and mark it clean

        outColor = resultColor;

        outColorHandle.setClean();

    }


    // Set ouput transparency

    if (plug == aOutTransparency || plug.parent() == aOutTransparency)

    {

        // Get the handle to the attribute

        MDataHandle outTransHandle =

            block.outputValue(aOutTransparency, &status);

        CHECK_MSTATUS(status);

        MFloatVector& outTrans = outTransHandle.asFloatVector();


        // Set the result and mark it clean

        outTrans = transparency;

        outTransHandle.setClean();

    }


    return MS::kSuccess;

}


// Init/Un-init fucntions

static const MString sRegistrantId("onbShaderPlugin");

MStatus initializePlugin(MObject obj)

{

    MFnPlugin plugin(obj, PLUGIN_COMPANY, "1.0", "Any");


    CHECK_MSTATUS(plugin.registerNode(

        OnbShader::nodeName,

        OnbShader::id,

        OnbShader::creator,

        OnbShader::initialize,

        MPxNode::kDependNode,

        &OnbShader::classification));


    CHECK_MSTATUS(

        MHWRender::MDrawRegistry::registerSurfaceShadingNodeOverrideCreator(

            OnbShader::drawDbClassification,

            sRegistrantId,

            onbShaderOverride::creator));


    CHECK_MSTATUS(onbShaderOverride::registerFragments());


    return MS::kSuccess;

}


MStatus uninitializePlugin(MObject obj)

{

    MFnPlugin plugin(obj);


    CHECK_MSTATUS(plugin.deregisterNode(OnbShader::id));


    CHECK_MSTATUS(

        MHWRender::MDrawRegistry::deregisterSurfaceShadingNodeOverrideCreator(

            OnbShader::drawDbClassification,

            sRegistrantId));


    CHECK_MSTATUS(onbShaderOverride::deregisterFragments());


    return MS::kSuccess;

}

// =====================================================================

// Copyright 2018 Autodesk, Inc.  All rights reserved.

//

// This computer source code  and related  instructions and comments are

// the unpublished confidential and proprietary information of Autodesk,

// Inc. and are  protected  under applicable  copyright and trade secret

// law. They may not  be disclosed to, copied or used by any third party

// without the prior written consent of Autodesk, Inc.

// =====================================================================