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# closestPointCmd.cpp

    //-
    // ==========================================================================
    // Copyright 1995,2006,2008 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.
    // ==========================================================================
    //+

    // MAYA HEADERS
    #include <maya/MFnPlugin.h>
    #include <maya/MDagPath.h>
    #include <maya/MFnMesh.h>
    #include <maya/MMeshIntersector.h>
    #include <maya/MItSelectionList.h>
    #include <maya/MItMeshPolygon.h>
    #include <maya/MObject.h>
    #include <maya/MSelectionList.h>
    #include <maya/MArgList.h>
    #include <maya/MFloatPoint.h>
    #include <maya/MFnDependencyNode.h>
    #include <maya/MFnPointLight.h>
    #include <maya/MFloatPointArray.h>
    #include <maya/MPxCommand.h>
    #include <maya/MDGModifier.h>
    #include <maya/MFnDagNode.h>
    #include <maya/MDagPath.h>
    #include <maya/MGlobal.h>
    #include <maya/MIOStream.h>

    #define MERR_CHK(status,msg) if ( !status ) { MGlobal::displayError(msg); } // cerr << msg << endl; }

    //
    //  PLUGIN DESCRIPTION
    //
    //  This is an example of the closest point between a point light and a mesh.
    //
    //
    //  PLUGIN INSTRUCTIONS
    //
    //  - create a point light and a poly plane (mesh)
    //  - run the command as such: closestPointCmd <pointLightName> <planeName>
    //  - a sphere will be created at the closest point
    //
    //  Use the following script to automatically display closest point on the mesh (assuming
    //  a point light and a mesh with the names used here exist):
    //
    //  global proc closestPointExample()
    //  {
    //      closestPointCmd pointLight1 pPlane1;
    //      select -r pointLight1;
    //  }
    //
    //  scriptJob -ac "pointLight1.tx" closestPointExample;
    //  scriptJob -ac "pointLight1.ty" closestPointExample;
    //  scriptJob -ac "pointLight1.tz" closestPointExample;
    //
    //  scriptJob -ac "pointLight1.rx" closestPointExample;
    //  scriptJob -ac "pointLight1.ry" closestPointExample;
    //  scriptJob -ac "pointLight1.rz" closestPointExample;
    //

    /*

    // Alternatively use the following code to demonstrate
    // the closest point
    //

        loadPlugin closestPointCmd;

        file -f -new;
        defaultPointLight(1, 1,1,1, 0, 0, 0,0,0, 1);
        move -r 0 5 0 ;
        polyPlane -w 1 -h 1 -sx 10 -sy 10 -ax 0 1 0 -cuv 2 -ch 1;
        scale -r 10 10 10 ;
        closestPointCmd pointLight1 pPlane1;

        file -f -new;
        defaultPointLight(1, 1,1,1, 0, 0, 0,0,0, 1);
        move -r 2 5 0 ;
        polyPlane -w 1 -h 1 -sx 10 -sy 10 -ax 0 1 0 -cuv 2 -ch 1;
        scale -r 10 10 10 ;
        closestPointCmd pointLight1 pPlane1;
        select -cl;

        unloadPlugin closestPointCmd ;

    */

    // MAIN CLASS FOR THE closestPointCmd COMMAND:
    class closestPointCmd : public MPxCommand
    {
        public:
            closestPointCmd();
            virtual ~closestPointCmd();
            static void* creator();
            bool isUndoable() const;
            MStatus doIt(const MArgList&);
            MStatus undoIt();

            void createDisplay( MPointOnMesh& info, MMatrix& matrix);
    };

    // CONSTRUCTOR:
    closestPointCmd::closestPointCmd()
    {
    }

    // DESTRUCTOR:
    closestPointCmd::~closestPointCmd()
    {
    }

    // FOR CREATING AN INSTANCE OF THIS COMMAND:
    void* closestPointCmd::creator()
    {
       return new closestPointCmd;
    }

    // MAKE THIS COMMAND NOT UNDOABLE:
    bool closestPointCmd::isUndoable() const
    {
       return false;
    }

    MStatus closestPointCmd::doIt(const MArgList& args)
    // Description:
    //      Determine the closest point between the point
    //      light and the mesh.
    //      If it does, it displays the point.
    {
        MStatus status = MStatus::kSuccess;

        if (args.length() != 2)
        {
            MGlobal::displayError("Need 2 items!");
            return MStatus::kFailure;
        }

        MSelectionList activeList;
        int i;
        for ( i = 0; i < 2; i++)
        {
            MString strCurrSelection;
            status = args.get(i, strCurrSelection);
            if (MStatus::kSuccess == status) activeList.add(strCurrSelection);
        }

        MItSelectionList iter(activeList);
        MFnPointLight fnLight;
        MFnDagNode dagNod;
        MFnDependencyNode fnDN;
        MDagPath pathToMesh;

        float fX = 0;
        float fY = 0;
        float fZ = 0;

        for ( ; !iter.isDone(); iter.next() )
        {
            MObject tempObjectParent, tempObjectChild;
            iter.getDependNode(tempObjectParent);

            if (tempObjectParent.apiType() == MFn::kTransform)
            {
                dagNod.setObject(tempObjectParent);
                tempObjectChild = dagNod.child(0, &status);
            }

            // check what type of object is selected
            if (tempObjectChild.apiType() == MFn::kPointLight)
            {
                MDagPath pathToLight;
                MERR_CHK(MDagPath::getAPathTo(tempObjectParent, pathToLight),
                        "Couldn't get a path to the pointlight");
                MERR_CHK(fnLight.setObject(pathToLight), "Failure on assigning light");

                status = fnDN.setObject(tempObjectParent);

                MPlug pTempPlug = fnDN.findPlug("translateX", &status);
                if (MStatus::kSuccess == status)
                {
                    pTempPlug.getValue(fX);
                }

                pTempPlug = fnDN.findPlug("translateY", &status);
                if (MStatus::kSuccess == status)
                {
                    pTempPlug.getValue(fY);
                }

                pTempPlug = fnDN.findPlug("translateZ", &status);
                if (MStatus::kSuccess == status)
                {
                    pTempPlug.getValue(fZ);
                }
            }
            else if (tempObjectChild.apiType() == MFn::kMesh)
            {
                MERR_CHK(MDagPath::getAPathTo(tempObjectChild, pathToMesh),
                    "Couldn't get a path to the pointlight");
            }
            else
            {
                MGlobal::displayError("Need a pointlight and a mesh");
                return MStatus::kFailure;
            }
        }

        MMeshIntersector intersector;
        MMatrix matrix = pathToMesh.inclusiveMatrix();
        MObject node = pathToMesh.node();
        status = intersector.create( node, matrix );
        if ( status )
        {
            MPoint point(fX,fY,fZ);
            MPointOnMesh pointInfo;
            cout << "Using point: " << point << endl;
            status = intersector.getClosestPoint( point, pointInfo );
            if ( status )
            {
                createDisplay( pointInfo, matrix );
            }
            else
            {
                MGlobal::displayError("Failed to get closest point");
            }
        }
        else
        {
            MGlobal::displayError("Failed to create intersector");
        }

        return status;
    }

    // UNDO THE COMMAND
    MStatus closestPointCmd::undoIt()
    {
        MStatus status;
        // undo not implemented
        return status;
    }

    void closestPointCmd::createDisplay( MPointOnMesh& info, MMatrix& matrix )
    {
        MPoint worldPoint( info.getPoint() );
        worldPoint = worldPoint * matrix;
        MVector worldNormal( info.getNormal() );
        worldNormal = worldNormal * matrix;
        worldNormal.normalize();

        MString strCommandString = "string $strBall[] = `polySphere -r 0.5`;";
        strCommandString += "$strBallName = $strBall[0];";
        strCommandString += "setAttr ($strBallName + \".tx\") ";
        strCommandString += worldPoint.x;
        strCommandString += ";";
        strCommandString += "setAttr ($strBallName + \".ty\") ";
        strCommandString += worldPoint.y;
        strCommandString += ";";
        strCommandString += "setAttr ($strBallName + \".tz\") ";
        strCommandString += worldPoint.z;
        strCommandString += ";";

        MGlobal::executeCommand(strCommandString);

        // Other info
        cout << "Normal: " << worldNormal << " face id: " << info.faceIndex() <<
            " triangle id: " << info.triangleIndex() << endl;
    }

    // INITIALIZE THE PLUGIN:
    MStatus initializePlugin(MObject obj)
    {
        MStatus status;
        MFnPlugin plugin(obj, PLUGIN_COMPANY, "9.0", "Any");
        status = plugin.registerCommand("closestPointCmd", closestPointCmd::creator);
        return status;
    }

    // UNINITIALIZE THE PLUGIN:
    MStatus uninitializePlugin(MObject obj)
    {
        MStatus status;
        MFnPlugin plugin(obj);
        plugin.deregisterCommand("closestPointCmd");
        return status;
    }