phongShader/phongShaderOverride.cpp

//-
// ===========================================================================
// Copyright 2015 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.
// ===========================================================================
//+

#include "phongShaderOverride.h"
#include <maya/MFnDependencyNode.h>
#include <maya/MShaderManager.h>

MHWRender::MPxSurfaceShadingNodeOverride* phongShaderOverride::creator(const MObject& obj)
{
    return new phongShaderOverride(obj);
}

phongShaderOverride::phongShaderOverride(const MObject& obj)
: MPxSurfaceShadingNodeOverride(obj)
, fObject(obj)
, fResolvedSpecularColorName("")
{
    fSpecularColor[0] = 0.5f;
    fSpecularColor[1] = 0.5f;
    fSpecularColor[2] = 0.5f;
}

phongShaderOverride::~phongShaderOverride()
{
}

MHWRender::DrawAPI phongShaderOverride::supportedDrawAPIs() const
{
    // works in both gl and dx
    return MHWRender::kOpenGL | MHWRender::kDirectX11 | MHWRender::kOpenGLCoreProfile;
}

MString phongShaderOverride::fragmentName() const
{
    // clear fResolvedSpecularColorName since we've rebuilt
    fResolvedSpecularColorName = "";

    // Just reuse Maya's phong surface shader
    return "mayaPhongSurface";
}

void phongShaderOverride::getCustomMappings(
    MHWRender::MAttributeParameterMappingList& mappings)
{
    // The "color" and "incandescence" attributes are all named the same as
    // the corresponding parameters on the fragment so they will map
    // automatically. Need to remap "diffuseReflectivity", "translucenceCoeff",
    // "reflectionGain" and "power" though.
    MHWRender::MAttributeParameterMapping diffuseMapping(
        "diffuse", "diffuseReflectivity", true, true);
    mappings.append(diffuseMapping);

    MHWRender::MAttributeParameterMapping translucenceMapping(
        "translucence", "translucenceCoeff", true, true);
    mappings.append(translucenceMapping);

    MHWRender::MAttributeParameterMapping reflectivityMapping(
        "reflectivity", "reflectionGain", true, true);
    mappings.append(reflectivityMapping);

    MHWRender::MAttributeParameterMapping powerMapping(
        "cosinePower", "power", true, true);
    mappings.append(powerMapping);

    // Our phong only uses a single float for specularity, while the Maya
    // phong fragment uses a full 3-float color. We could add a remap fragment
    // in front to expand the float to a 3-float, but it is simpler here to
    // just set the parameter manually in updateShader(). So add an empty
    // mapping to ensure the parameter gets renamed.
    MHWRender::MAttributeParameterMapping specColMapping(
        "specularColor", "", true, true);
    mappings.append(specColMapping);

}

MString phongShaderOverride::primaryColorParameter() const
{
    // Use the color parameter from the phong fragment as the primary color
    return "color";
}

MString phongShaderOverride::bumpAttribute() const
{
    // Use the "normalCamera" attribute to recognize bump connections
    return "normalCamera";
}

void phongShaderOverride::updateDG()
{
    MStatus status;
    MFnDependencyNode node(fObject, &status);
    if (status)
    {
        float specularity = 0.5f;
        node.findPlug("specularity", true).getValue(specularity);

        // Expand specularity to a 3-float
        fSpecularColor[0] = specularity;
        fSpecularColor[1] = specularity;
        fSpecularColor[2] = specularity;
    }
}

void phongShaderOverride::updateShader(
    MHWRender::MShaderInstance& shader,
    const MHWRender::MAttributeParameterMappingList& mappings)
{
    // Cache resolved name if found to avoid lookup on every update
    if (fResolvedSpecularColorName.length() == 0)
    {
        const MHWRender::MAttributeParameterMapping* mapping =
            mappings.findByParameterName("specularColor");
        if (mapping)
        {
            fResolvedSpecularColorName = mapping->resolvedParameterName();
        }
    }

    // Set parameter
    if (fResolvedSpecularColorName.length() > 0)
    {
        shader.setParameter(fResolvedSpecularColorName, fSpecularColor);
    }
}