slopeShader/slopeShaderBehavior.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 "slopeShaderBehavior.h"
#include <maya/MGlobal.h>
#include <maya/MPlugArray.h>
#include <maya/MFnDagNode.h>
#include <maya/MObjectArray.h>

slopeShaderBehavior::slopeShaderBehavior()
//
//  Description:
//      Constructor
//
{
}

slopeShaderBehavior::~slopeShaderBehavior()
//
//  Description:
//      Destructor
//
{
}

void *slopeShaderBehavior::creator()
//
//  Description:
//      Returns a new instance of this class
//
{
    return new slopeShaderBehavior;
}

bool slopeShaderBehavior::shouldBeUsedFor( MObject &sourceNode, MObject &destinationNode,
                                           MPlug &sourcePlug, MPlug &destinationPlug)
//
//  Description:
//      Overloaded function from MPxDragAndDropBehavior
//  this method will return true if it is going to handle the connection
//  between the two nodes given.
//
{
    bool result = false;

    if(sourceNode.hasFn(MFn::kLambert))
    {
        //if the source node was a lambert
        //than we will check the downstream connections to see 
        //if a slope shader is assigned to it.
        //
        MObject shaderNode;
        MFnDependencyNode src(sourceNode);
        MPlugArray connections;

        src.getConnections(connections);
        for(unsigned i = 0; i < connections.length(); i++)
        {
            //check the incoming connections to this plug
            //
            MPlugArray connectedPlugs;
            connections[i].connectedTo(connectedPlugs, true, false);
            for(unsigned j = 0; j < connectedPlugs.length(); j++)
            {
                //if the incoming node is a slope shader than 
                //set shaderNode equal to it and break out of the inner 
                //loop
                //
                if(MFnDependencyNode(connectedPlugs[j].node()).typeName() == "slopeShader")
                {
                    shaderNode = connectedPlugs[j].node();
                    break;
                }
            }

            //if the shaderNode is not null
            //than we have found a slopeShader
            //
            if(!shaderNode.isNull())
            {
                //if the destination node is a mesh than we will take
                //care of this connection so set the result to true
                //and break out of the outer loop
                //
                if(destinationNode.hasFn(MFn::kMesh))
                    result = true;

                break;
            }
        }
    }
    if(MFnDependencyNode(sourceNode).typeName() == "slopeShader")
    //if the sourceNode is a slope shader than check what we
    //are dropping on to
    //
    {
        if(destinationNode.hasFn(MFn::kLambert))
            result = true;
        else if(destinationNode.hasFn(MFn::kMesh))
            result = true;
    }   

    return result;
}

MStatus slopeShaderBehavior::connectNodeToNode( MObject &sourceNode, MObject &destinationNode, bool force )
//
//  Description:
//      Overloaded function from MPxDragAndDropBehavior
//  this method will handle the connection between the slopeShader and the shader it is
//  assigned to as well as any meshes that it is assigned to. 
//
{
    MStatus result = MS::kFailure;
    MFnDependencyNode src(sourceNode);

    //if we are dragging from a lambert
    //we want to check what we are dragging
    //onto.
    if(sourceNode.hasFn(MFn::kLambert))
    {
        MObject shaderNode;
        MPlugArray connections;
        MObjectArray shaderNodes;
        shaderNodes.clear();

        //if the source node was a lambert
        //than we will check the downstream connections to see 
        //if a slope shader is assigned to it.
        //
        src.getConnections(connections);
        unsigned i;
        for(i = 0; i < connections.length(); i++)
        {
            //check the incoming connections to this plug
            //
            MPlugArray connectedPlugs;
            connections[i].connectedTo(connectedPlugs, true, false);
            for(unsigned j = 0; j < connectedPlugs.length(); j++)
            {
                //if the incoming node is a slope shader than 
                //append the node to the shaderNodes array
                //
                MObject currentnode = connectedPlugs[j].node();
                if(MFnDependencyNode(currentnode).typeName() == "slopeShader")
                {
                    shaderNodes.append(currentnode);
                }
            }
        }

        //if we found a shading node
        //than check the destination node 
        //type to see if it is a mesh
        //
        if(shaderNodes.length() > 0)
        {
            MFnDependencyNode dest(destinationNode);
            if(destinationNode.hasFn(MFn::kMesh))
            {
                //if the node is a mesh than for each slopeShader
                //connect the worldMesh attribute to the dirtyShaderPlug
                //attribute to force an evaluation of the node when the mesh
                //changes
                //
                for(i = 0; i < shaderNodes.length(); i++)
                {
                    MPlug srcPlug = dest.findPlug("worldMesh");
                    MPlug destPlug = MFnDependencyNode(shaderNodes[i]).findPlug("dirtyShaderPlug");

                    if(!srcPlug.isNull() && !destPlug.isNull())
                    {
                        MString cmd = "connectAttr -na ";
                        cmd += srcPlug.name() + " ";
                        cmd += destPlug.name();
                        MGlobal::executeCommand(cmd);
                    }
                }

                //get the shading engine so we can assign the shader
                //to the mesh after doing the connection
                //
                MObject shadingEngine = findShadingEngine(sourceNode);

                //if there is a valid shading engine than make
                //the connection
                //
                if(!shadingEngine.isNull())
                {
                    MString cmd = "sets -edit -forceElement ";
                    cmd += MFnDependencyNode(shadingEngine).name() + " ";
                    cmd += MFnDagNode(destinationNode).partialPathName();
                    result = MGlobal::executeCommand(cmd);
                }
            }
        }
    }
    else if(src.typeName() == "slopeShader")
    //if we are dragging from a slope shader
    //than we want to see what we are dragging onto
    //
    {
        if(destinationNode.hasFn(MFn::kMesh))
        {
            //if the user is dragging onto a mesh
            //than make the connection from the worldMesh
            //to the dirtyShader plug on the slopeShader
            //
            MFnDependencyNode dest(destinationNode);
            MPlug srcPlug = dest.findPlug("worldMesh");
            MPlug destPlug = src.findPlug("dirtyShaderPlug");
            if(!srcPlug.isNull() && !destPlug.isNull())
            {
                MString cmd = "connectAttr -na ";
                cmd += srcPlug.name() + " ";
                cmd += destPlug.name();
                result = MGlobal::executeCommand(cmd);
            }
        }
    }

    return result;
}

MStatus slopeShaderBehavior::connectNodeToAttr( MObject &sourceNode, MPlug &destinationPlug, bool force )
//
//  Description:
//      Overloaded function from MPxDragAndDropBehavior
//  this method will assign the correct output from the slope shader 
//  onto the given attribute.
//
{
    MStatus result = MS::kFailure;
    MFnDependencyNode src(sourceNode);

    //if we are dragging from a slopeShader
    //to a shader than connect the outColor
    //plug to the plug being passed in
    //
    if(destinationPlug.node().hasFn(MFn::kLambert)) {
        if(src.typeName() == "slopeShader")
        {
            MPlug srcPlug = src.findPlug("outColor");
            if(!srcPlug.isNull() && !destinationPlug.isNull())
            {
                MString cmd = "connectAttr ";
                cmd += srcPlug.name() + " ";
                cmd += destinationPlug.name();
                result = MGlobal::executeCommand(cmd);
            }
        }
    } else {
        //in all of the other cases we do not need the plug just the node
        //that it is on
        //
        MObject destinationNode = destinationPlug.node();
        result = connectNodeToNode(sourceNode, destinationNode, force);
    }
        
    return result;
}

MObject slopeShaderBehavior::findShadingEngine(MObject &node)
//
//  Description:
//      Given the material MObject this method will
//  return the shading group that it is assigned to.
//  if there is no shading group associated with
//  the material than a null MObject is apssed back.
//
{
    MFnDependencyNode nodeFn(node);
    MPlug srcPlug = nodeFn.findPlug("outColor");
    MPlugArray nodeConnections;
    srcPlug.connectedTo(nodeConnections, false, true);
    //loop through the connections
    //and find the shading engine node that
    //it is connected to
    //
    for(unsigned i = 0; i < nodeConnections.length(); i++)
    {
        if(nodeConnections[i].node().hasFn(MFn::kShadingEngine))
            return nodeConnections[i].node();
    }

    //no shading engine associated so return a
    //null MObject
    //
    return MObject();
}