contrastShader/contrastShader.cpp
 
 
 
contrastShader/contrastShader.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    :    Contrast shader plugin
//
//    Notes        :     The contrast operation consists in
//                redistributing the energy around the middle
//                point. In other words: every intensity below
//                0.5 is pushed towards black, and every
//                intensity above is pushed towards white.
//                The trick is to do that in a "smooth" way.
//
//        The way to do that is:
//            On interval [0,0.5] apply a gamma to intensity
//            On interval [0.5,1] apply an "inverted" gamma to intensity
//
//        That is:
//            When I<0.5,    newI=0.5*(2*I)^contrast
//            When I>=0.5,    newI=1-0.5*(2*(1-I))^contrast
//
//        This function is C1 on [0,1], and if contrast==1, it is the
//        identity.
//
//        The bias value stems from: why 0.5 and not something else ?
//        So, we use a function f to remap the [0,1] interval on itself
//        with the constraint:
//            f(0)=0
//            f(bias)=0.5
//            f(1)=1
//        and we compose with the above function.
//
//        Of course, when bias=0.5, f *has* to be the identity, and of
//        course, f *has* to be smooth.
//        A good candidate is f(x)=x^alpha, with alpha=log(0.5)/log(bias)
//

#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 Contrast:public MPxNode
{
        public:
                    Contrast();
    virtual         ~Contrast();

        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;
        static MObject aContrast;
        static MObject aBias;

        // Output attributes
        static MObject aOutColor;
};

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

        virtual ~ContrastOverride();

        virtual MHWRender::DrawAPI supportedDrawAPIs() const;

        virtual MString fragmentName() const;

private:
        ContrastOverride(const MObject& obj);

        MString fFragmentName;
};

//
// Node definition
// static data
MTypeId Contrast::id( 0x81008 );

// Attributes
MObject Contrast::aColor;
MObject Contrast::aContrast;
MObject Contrast::aBias;

MObject Contrast::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 Contrast::postConstructor( )
{
        setMPSafe(true);
}

//
// DESCRIPTION:
Contrast::Contrast()
{
}

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

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

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

    // Create input attributes

        aColor = nAttr.createColor("inputColor", "ic");
        MAKE_INPUT(nAttr);

        aContrast = nAttr.createColor("contrast", "c");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(1.f, 1.f, 1.f));

        aBias = nAttr.createColor("bias", "b");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(.5f, .5f, .5f));

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

    /* Plug inputs and outputs
    ---------------------------*/
    CHECK_MSTATUS(addAttribute(aColor));
    CHECK_MSTATUS(addAttribute(aContrast));
    CHECK_MSTATUS(addAttribute(aBias));
    CHECK_MSTATUS(addAttribute(aOutColor));

    /* Build dependancies
    ----------------------*/
    CHECK_MSTATUS(attributeAffects(aColor,    aOutColor));
    CHECK_MSTATUS(attributeAffects(aContrast, aOutColor));
    CHECK_MSTATUS(attributeAffects(aBias,     aOutColor));

    return MS::kSuccess;
}

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

    MFloatVector resultColor;
    MFloatVector & col = block.inputValue(aColor).asFloatVector();
    MFloatVector & cont = block.inputValue(aContrast).asFloatVector();
    MFloatVector & bias = block.inputValue(aBias).asFloatVector();

    float xp;
    float logp5= logf(0.5F);

    xp = powf(col[0], logp5/logf(bias[0]));
    resultColor[0] = xp<0.5F ?
                0.5F*powf(2.0F*xp, cont[0]) :
                1.0F-0.5F*powf(2.0F*(1.0F-xp), cont[0]);

    xp = powf(col[1], logp5/logf(bias[1]));
    resultColor[1] = xp<0.5F ?
                0.5F*powf(2.0F*xp, cont[1]) :
                1.0F-0.5F*powf(2.0F*(1.0F-xp), cont[1]);

    xp = powf(col[2], logp5/logf(bias[2]));
    resultColor[2] = xp<0.5F ?
                0.5F*powf(2.0F*xp, cont[2]) :
                1.0F-0.5F*powf(2.0F*(1.0F-xp), cont[2]);

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

    return MS::kSuccess;
}

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

ContrastOverride::ContrastOverride(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("contrastShaderPluginFragment");
        static const char* sFragmentBody =
                "<fragment uiName=\"contrastShaderPluginFragment\" name=\"contrastShaderPluginFragment\" type=\"plumbing\" class=\"ShadeFragment\" version=\"1.0\">"
                "       <description><![CDATA[Contrast utility fragment]]></description>"
                "       <properties>"
                "               <float3 name=\"inputColor\" />"
                "               <float3 name=\"contrast\" />"
                "               <float3 name=\"bias\" />"
                "       </properties>"
                "       <values>"
                "               <float3 name=\"inputColor\" value=\"0.5,0.5,0.5\" />"
                "               <float3 name=\"contrast\" value=\"1.0,1.0,1.0\" />"
                "               <float3 name=\"bias\" value=\"0.5,0.5,0.5\" />"
                "       </values>"
                "       <outputs>"
                "               <float3 name=\"outColor\" />"
                "       </outputs>"
                "       <implementation>"
                "       <implementation render=\"OGSRenderer\" language=\"Cg\" lang_version=\"2.1\">"
                "               <function_name val=\"contrastShaderPluginFragment\" />"
                "               <source><![CDATA["
                "float3 contrastShaderPluginFragment(float3 inputColor, float3 contrast, float3 bias) \n"
                "{ \n"
                "       const float logp5 = log(0.5f); \n"
                "       float3 result; \n"
                "       float xp = pow(inputColor.r, logp5/log(bias.r)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.r = 0.5f*pow(2.0f*xp, contrast.r); \n"
                "       } else { \n"
                "               result.r = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.r); \n"
                "       } \n"
                "       xp = pow(inputColor.g, logp5/log(bias.g)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.g = 0.5f*pow(2.0f*xp, contrast.g); \n"
                "       } else { \n"
                "               result.g = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.g); \n"
                "       } \n"
                "       xp = pow(inputColor.b, logp5/log(bias.b)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.b = 0.5f*pow(2.0f*xp, contrast.b); \n"
                "       } else { \n"
                "               result.b = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.b); \n"
                "       } \n"
                "       return result; \n"
                "} \n]]>"
                "               </source>"
                "       </implementation>"
                "       <implementation render=\"OGSRenderer\" language=\"HLSL\" lang_version=\"11.0\">"
                "               <function_name val=\"contrastShaderPluginFragment\" />"
                "               <source><![CDATA["
                "float3 contrastShaderPluginFragment(float3 inputColor, float3 contrast, float3 bias) \n"
                "{ \n"
                "       const float logp5 = log(0.5f); \n"
                "       float3 result; \n"
                "       float xp = pow(inputColor.r, logp5/log(bias.r)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.r = 0.5f*pow(2.0f*xp, contrast.r); \n"
                "       } else { \n"
                "               result.r = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.r); \n"
                "       } \n"
                "       xp = pow(inputColor.g, logp5/log(bias.g)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.g = 0.5f*pow(2.0f*xp, contrast.g); \n"
                "       } else { \n"
                "               result.g = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.g); \n"
                "       } \n"
                "       xp = pow(inputColor.b, logp5/log(bias.b)); \n"
                "       if (xp < 0.5f) { \n"
                "               result.b = 0.5f*pow(2.0f*xp, contrast.b); \n"
                "       } else { \n"
                "               result.b = 1.0f - 0.5f*pow(2.0f*(1.0f-xp), contrast.b); \n"
                "       } \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;
                        }
                }
        }
}

ContrastOverride::~ContrastOverride()
{
}

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

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

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

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

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

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

        return MS::kSuccess;
}

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

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

        return MS::kSuccess;
}