listLightLinksCmd/listLightLinksCmd.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.
// ==========================================================================
//+

//  
// DESCRIPTION:
// 
// Produces the MEL command "listLightLinks". 
// 
// This example demonstrates how to use the MLightLinks class to query
// the light linking information in Maya. The command takes no arguments.
// If the currently selected object is a light, then the command will
// select all objects illuminated by that light. If the currently
// selected object is a piece of geometry, then the command will select
// all the lights that illuminate that geometry. 
//

#include <maya/MSimple.h>
#include <maya/MLightLinks.h>
#include <maya/M3dView.h>
#include <maya/MDagPathArray.h>
#include <maya/MSelectionList.h>
#include <maya/MDagPath.h>
#include <maya/MGlobal.h>
#include <maya/MStringArray.h>
#include <maya/MItSelectionList.h>
#include <math.h>

DeclareSimpleCommand( listLightLinks, PLUGIN_COMPANY, "4.5");

MStatus listLightLinks::doIt( const MArgList& args )
//
//  Description:
//      Implements the MEL listLightLinks command.  After parsing the 
//      information stored in Maya's light linker nodes, it examines
//      the first item on the selection list.  If the item is an object,
//      then the command selects all lights that are linked to that object.
//      If the item is a light, then it will select all of the objects 
//      that are linked to that light.
//
//  Arguments:
//      args - The argument list that was passed to the command from MEL.
//             This command takes no arguments.
//
//  Return Value:
//      MS::kSuccess - command succeeded
//      MS::kFailure - command failed (returning this value will cause the 
//                     MEL script that is being run to terminate unless the
//                     error is caught using a "catch" statement).
//
{
    MStatus stat = MS::kSuccess;
    clearResult();

    // Parse the links on the current scene's light linker node(s).
    //
    MLightLinks lightLink;
    bool parseStatus;
    parseStatus = lightLink.parseLinks(MObject::kNullObj);

    if( !parseStatus )
    {
        setResult( "Error parsing light links\n" );
        return MS::kFailure;
    }

    // Get the first object (or component) on the selection list.
    //
    MSelectionList selectList;
    MDagPath dagPath;
    MObject component;
    MGlobal::getActiveSelectionList( selectList );
    selectList.getDagPath( 0, dagPath, component );
    dagPath.extendToShape();

    // Selection list to store entities linked to the selected light or
    // object.
    //
    MSelectionList newSelection;
    newSelection.clear();

    // Stores the command result.
    //
    char resultString[512];

    // If the object is a surface, we'll select all the lights linked to it.
    // If the object is a light, we'll select all the objects linked to it.
    //
    if( dagPath.hasFn( MFn::kLight ) )
    {
        // Select objects linked to this light.
        //
        MSelectionList objects;
        objects.clear();
        lightLink.getLinkedObjects( dagPath, objects );

        newSelection.merge( objects );

        sprintf( resultString, "Selecting objects linked to light %s", 
                 dagPath.fullPathName().asChar() );

    }
    else
    {
        // Select lights linked to this object.
        //
        MDagPathArray lights;
        lights.clear();
        lightLink.getLinkedLights( dagPath, component, lights );

        for( unsigned int j = 0; j < lights.length(); j++ )
        {
            const MDagPath& path = lights[j];
            newSelection.add( path );
        }

        sprintf( resultString, "Selecting lights linked to object %s", 
                 dagPath.fullPathName().asChar() );

    } 

    // Select the linked entities.
    //
    MGlobal::setActiveSelectionList( newSelection );

    setResult( resultString );
    return stat;
}