ShadingConnection.cpp

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// ShadingConnection.cpp

// DESCRIPTION:  This class stores useful information about
//                               a shader's attribute, including what's connected upstream of it.
//                               It also automatically passes through shader switches.
//
// AUTHOR: Christian Laforte
//

#include <maya/MObject.h>
#include <maya/MColor.h>
#include <maya/MString.h>
#include <maya/MStringArray.h>
#include <maya/MFnDependencyNode.h>
#include <maya/MPlug.h>
#include <maya/MPlugArray.h>

#include <assert.h>


#include "ShadingConnection.h"

ShadingConnection::ShadingConnection(MObject shaderObj, MString shapeName, MString attribute /* = "" */)
{
        // Store those input values for later use.
        this->m_shaderObj = shaderObj;
        this->m_shapeName = shapeName;

        // By default, the connection is direct until proven otherwise.
        this->m_directConnection = true;

        if (attribute != "")
                traverseAttribute(attribute);
}

ShadingConnection::TYPE ShadingConnection::traverseAttribute(MString attributeName)
{
        // Get a plug to the attribute.
        MStatus status;
        MFnDependencyNode shaderNode(m_shaderObj);

        MPlug plug = shaderNode.findPlug( attributeName, &status );
        assert(status);

        this->m_attributeName = attributeName;

        return analyzePlug(plug);
}
        
ShadingConnection::TYPE ShadingConnection::analyzePlug(MPlug plug)
{
        MStatus status;

        // Find all incoming connections.
        MPlugArray connectedElements;
        plug.connectedTo( connectedElements, true, false, &status );
        assert(status);
        
        if (connectedElements.length() == 0)
        {
                // It's a constant color... set it now and return.
                unsigned int numChildren = plug.numChildren();
                assert(numChildren == 3);

                float red, green, blue;
                plug.child(0).getValue(red);
                plug.child(1).getValue(green);
                plug.child(2).getValue(blue);

                return setConstantColor(MColor(red, green, blue, 1.0));
        }
        
        // The plug is actually connected on a different shading node.
        MObject connectedObject = connectedElements[0].node(&status);
        assert(status);

        // If this is a triple shading switch, go through it.
        if (connectedObject.hasFn(MFn::kTripleShadingSwitch))
        {
                return traverseTripleShadingSwitch(connectedObject);
        }

        // Set the object and return the appropriate type.
        return setTexture(connectedObject);
}

ShadingConnection::TYPE ShadingConnection::traverseTripleShadingSwitch(MObject connectedObject)
{                       
        // The connection cannot be direct anymore.
        m_directConnection = false;
        
        MFnDependencyNode node(connectedObject);

        MStatus status;
        MPlug inputPlug = node.findPlug( "input" );
        
        unsigned int numElements = inputPlug.numElements();
        unsigned int numChildren = inputPlug.numChildren();
        
        // It is assumed that the first child of this input compound attribute is
        // a "inTexture" attribute and the the second child is the inShape attribute.
        // This assumption should always be safe, unless some drastic changes occured in the
        // implementation of the shading switches... in which case this code won't work, so
        // we would throw an exception.
        assert( numChildren >= 2); // "Abnormal hierarchy in switching node."
        
        // Go through each row of the switch table.
        for (unsigned int index = 0; index < numElements; index++)
        {
                MPlug inTexturePlug = inputPlug.elementByPhysicalIndex(index).child(0);
                MPlug inShapePlug = inputPlug.elementByPhysicalIndex(index).child(1);                           

                MPlugArray inShapeConnections;
                inShapePlug.connectedTo( inShapeConnections, true, false, &status );
                
                // Check if one of the corresponding shapes matches the given shape name.
                unsigned int numCorrespondingShapes = inShapeConnections.length();
                for (unsigned int shapeNum = 0; shapeNum < numCorrespondingShapes; shapeNum++)
                {
                        MObject inShapeObj = inShapeConnections[0].node(&status);
                        assert(status);
                        
                        MFnDependencyNode inShape(inShapeObj);
                        MString inShapeName = inShape.name();

                        if (inShapeName == m_shapeName)
                                return analyzePlug(inTexturePlug);
                }
        }

        // If there was no special case in the switch for our shape, check the default.
        MPlug defaultPlug = node.findPlug("default");
        return analyzePlug(defaultPlug);
}

ShadingConnection::TYPE ShadingConnection::type()
{
        return m_type;
}

MColor ShadingConnection::constantColor()
{
        assert(m_type == CONSTANT_COLOR);
        return m_constantColor;
}

MObject ShadingConnection::texture()
{
        assert(m_type == TEXTURE);
        return m_texture;
}

MObject ShadingConnection::shaderObj()
{
        return m_shaderObj;
}

MString ShadingConnection::shaderName()
{
        MStatus stat;
        MFnDependencyNode shaderNode(m_shaderObj, &stat);
        assert(stat);
        return shaderNode.name();
}

MString ShadingConnection::attributeName()
{
        return m_attributeName;
}

MString ShadingConnection::shapeName()
{
        return m_shapeName;
}

ShadingConnection::TYPE ShadingConnection::setConstantColor(MColor col)
{
        m_constantColor = col;
        m_type = CONSTANT_COLOR;

        // Reset m_texture to prevent misinterpretation.
        m_texture = MObject();

        return m_type;
}

ShadingConnection::TYPE ShadingConnection::setTexture(MObject texture)
{
        m_texture = texture;
        m_type = TEXTURE;

        // Reset m_color to prevent misinterpretation.
        m_constantColor = MColor();

        return m_type;
}

bool ShadingConnection::isDirectConnection()
{
        return m_directConnection;
}