cvPosCmd/cvPosCmd.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 "cvPos".
//
// This example demonstrates how to obtain the world or local space position of a NURBS CV or a polygonal vertex.
// 
// The command accepts the flags -l/-local or -w/-world (where world is the default) to indicate whether a local
// or world space location of the CV is required. The command can handle at most 1 CV per invocation because it returns
// the coordinate as 3 element (a MEL float array). If no arguments are provided to the command, it checks the
// active selection list. If exactly one CV or vertex is present in that list, it returns its location.
// If more than one is selected, an error occurs.
//
// Alternatively, a single component can be specified on the command line using the MEL syntax. For example:
// cvPos nurbsSphereShape1.cv[0][0];
// It returns the world space position of the specified CV. 
//

#include <maya/MPxCommand.h>
#include <maya/MStatus.h>
#include <maya/MArgList.h>
#include <maya/MFnPlugin.h>
#include <maya/MObject.h>
#include <maya/MGlobal.h>
#include <maya/MDagPath.h>
#include <maya/MItSelectionList.h>
#include <maya/MSelectionList.h>
#include <maya/MString.h>
#include <maya/MPoint.h>

#include <maya/MItCurveCV.h>
#include <maya/MItSurfaceCV.h>
#include <maya/MItMeshVertex.h>

#include <maya/MIOStream.h>

class cvPos : public MPxCommand
{
public:
                cvPos();
        ~cvPos() override;

    MStatus     doIt ( const MArgList& args ) override;
    MStatus     redoIt () override;
    MStatus     undoIt () override;
    bool        isUndoable() const override;

    static      void* creator();

private:
    MPoint      point;
};

cvPos::cvPos() :
    point(0.0, 0.0, 0.0)
{
}

cvPos::~cvPos() {}

void* cvPos::creator()
{
    return new cvPos;
}

bool cvPos::isUndoable() const
{
    return true;
}

MStatus cvPos::undoIt()
{
    return MS::kSuccess;
}

MStatus cvPos::doIt( const MArgList& args )
{

    MString componentName;
    MSpace::Space transformSpace = MSpace::kWorld;

    for (unsigned int i = 0; i < args.length (); i++)
    {
        MString argStr;
        args.get (i, argStr);
        if (MString ("-l") == argStr || MString ("-local") == argStr)
            transformSpace = MSpace::kObject;
        else if (MString ("-w") == args.asString (i) ||
                 MString ("-world") == argStr)
            transformSpace = MSpace::kWorld;
        else
            componentName = argStr;
    }

    MObject     component;
    MDagPath    dagPath;

    if (!componentName.length ()) {
        MSelectionList activeList;

        MGlobal::getActiveSelectionList (activeList);

        MItSelectionList iter (activeList, MFn::kComponent);
        if (iter.isDone ()) {
            displayError ("No components selected");
            return MS::kFailure;
        } else {
            iter.getDagPath (dagPath, component);
            iter.next ();
            if (!iter.isDone ()) {
                displayError ("More than one component is selected");
                return MS::kFailure;
            }
        }
    } else {
        MSelectionList list;

        if (! list.add( componentName ) ) {
            componentName += ": no such component";
            displayError(componentName);
            return MS::kFailure; // no such component
        }
        MItSelectionList iter( list );
        iter.getDagPath( dagPath, component );
    }

    if (component.isNull()) {
        displayError("not a component");
        return MS::kFailure;
    }

    switch (component.apiType()) {
    case MFn::kCurveCVComponent:
        {
            MItCurveCV curveCVIter( dagPath, component );
            point = curveCVIter.position(transformSpace );
            curveCVIter.next();
            if (!curveCVIter.isDone()) {
                displayError ("More than one component is selected");
                return MS::kFailure;
            }
            break;
        }

    case MFn::kSurfaceCVComponent:
        {
            MItSurfaceCV surfCVIter( dagPath, component, true );
            point = surfCVIter.position(transformSpace );
            surfCVIter.next();
            if (!surfCVIter.isDone()) {
                displayError ("More than one component is selected");
                return MS::kFailure;
            }
            break;
        }

    case MFn::kMeshVertComponent:
        {
            MItMeshVertex vertexIter( dagPath, component );
            point = vertexIter.position(transformSpace );
            vertexIter.next();
            if (!vertexIter.isDone()) {
                displayError ("More than one component is selected");
                return MS::kFailure;
            }
            break;
        }

    default:
        cerr << "Selected unsupported type: (" << component.apiType()
             << "): " << component.apiTypeStr() << endl;
    }

    return redoIt();
}

MStatus cvPos::redoIt()
{
    clearResult();
    appendToResult( point.x );
    appendToResult( point.y );
    appendToResult( point.z );

    return MS::kSuccess;
}

MStatus initializePlugin( MObject obj )
{
    MStatus   status;
    MFnPlugin plugin( obj, PLUGIN_COMPANY, "3.0", "Any");

    status = plugin.registerCommand( "cvPos", cvPos::creator );
    if (!status) {
        status.perror("registerCommand");
        return status;
    }

    return status;
}

MStatus uninitializePlugin( MObject obj )
{
    MStatus   status;
    MFnPlugin plugin( obj );

    status = plugin.deregisterCommand( "cvPos" );
    if (!status) {
        status.perror("deregisterCommand");
        return status;
    }

    return status;
}