contrastShader/contrastShader.cpp

//
//    Description    :    Contrast shader plugin
//    Produces dependency graph node ContrastNode
 
//    This node is an example of color manipulation.
 
//    The inputs for this node are input color, contrast and bias. 
//    The contrast and bias inputs are 3 float values so that they can be applied to each rgb channel of an input color separately.
 
//    The output attribute of the ContrastNode node is called "outColor". 
//    It is a 3 float value that represents the resulting color derived from the effective contrast and bias settings. 
//    To use this shader, create a ContrastNode and connect its output to an input of a surface/shader node such as Color.

//
//    Notes        :     The contrast operation consists of
//                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();
            ~Contrast() override;

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

    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);

    ~ContrastOverride() override;

    MHWRender::DrawAPI supportedDrawAPIs() const override;

    MString fragmentName() const override;

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:
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 render=\"OGSRenderer\" language=\"GLSL\" lang_version=\"3.0\">"
        "       <function_name val=\"contrastShaderPluginFragment\" />"
        "       <source><![CDATA["
        "vec3 contrastShaderPluginFragment(vec3 inputColor, vec3 contrast, vec3 bias) \n"
        "{ \n"
        "   const float logp5 = log(0.5f); \n"
        "   vec3 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 | MHWRender::kOpenGLCoreProfile;
}

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;
}
// =====================================================================
// 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.
// =====================================================================