surfaceTwistCmd.cpp
 
#include <math.h>
#include <maya/MIOStream.h>
#include <maya/MPxCommand.h>
#include <maya/MStatus.h>
#include <maya/MObject.h>
#include <maya/MFnPlugin.h>
#include <maya/MString.h>
#include <maya/MArgList.h>
#include <maya/MGlobal.h>
#include <maya/MPoint.h>
#include <maya/MVector.h>
#include <maya/MMatrix.h>
#include <maya/MDagPath.h>
#include <maya/MSelectionList.h>
#include <maya/MItSelectionList.h>
#include <maya/MItSurfaceCV.h>
#include <maya/MItMeshVertex.h>
class surfaceTwist : public MPxCommand {
public:
                                        surfaceTwist();
        virtual                 ~surfaceTwist();
        virtual MStatus doIt( const MArgList& args );
        static void*    creator();
};
#define NUM_SPANS        30
#define WIDTH            10.0
#define VERTICAL_SCALING 4.0
surfaceTwist::~surfaceTwist() {}
surfaceTwist::surfaceTwist() {}
void* surfaceTwist::creator()
{
        return new surfaceTwist;
}
static MStatus twistNurbsSurface(MDagPath& objectPath, MObject& component)
{
        MStatus status;
        MPoint  center;
        MVector toCenter( -center.x, 0.0, -center.y );
        double  rotFactor = 0.5;
        
        
        MItSurfaceCV cvIter( objectPath, component, true, &status );
        if ( MS::kSuccess == status ) {
                
                
                for ( ; !cvIter.isDone(); cvIter.nextRow() ) {
                        for ( ; !cvIter.isRowDone(); cvIter.next() ) {
                                
                                
                                MPoint pnt = cvIter.position( MSpace::kWorld );
                                pnt = pnt + toCenter;
                                
                                
                                double rotation = pnt.y * rotFactor;
                                MMatrix rotMatrix;
                                
                                
                                rotMatrix(0,0) = cos( rotation );
                                rotMatrix(0,2) = sin( rotation );
                                rotMatrix(2,0) = -sin( rotation );
                                rotMatrix(2,2) = cos( rotation );
                                pnt = ( pnt * rotMatrix ) - toCenter;
                                status = cvIter.setPosition( pnt, MSpace::kWorld );
                                if ( MS::kSuccess != status )
                                        break;
                        }
                }
                
                
                cvIter.updateSurface();
                return MS::kSuccess;
        } else
                return MS::kFailure;
}
static MStatus twistPolygon(MDagPath& objectPath, MObject& component)
{
        MStatus status;
        MPoint  center;
        MVector toCenter( -center.x, 0.0, -center.y );
        double  rotFactor = 0.5;
        MItMeshVertex vertIter( objectPath, component, &status );
        if ( MS::kSuccess == status ) {
                
                
                for ( ; !vertIter.isDone(); vertIter.next() ) {
                        
                        
                        MPoint pnt = vertIter.position( MSpace::kWorld );
                        pnt = pnt + toCenter;
                        
                        
                        double rotation = pnt.y * rotFactor;
                        MMatrix rotMatrix;
                        
                        
                        rotMatrix(0,0) = cos( rotation );
                        rotMatrix(0,2) = sin( rotation );
                        rotMatrix(2,0) = -sin( rotation );
                        rotMatrix(2,2) = cos( rotation );
                        pnt = ( pnt * rotMatrix ) - toCenter;
                        status = vertIter.setPosition( pnt, MSpace::kWorld );
                        if ( MS::kSuccess != status )
                                break;
                }
                
                
                vertIter.updateSurface();
                return MS::kSuccess;
        } else
                return MS::kFailure;
}
MStatus surfaceTwist::doIt( const MArgList& )
{
        MStatus status;
        
        
        MSelectionList slist;
        MGlobal::getActiveSelectionList( slist );
        MItSelectionList iter( slist );
        if (iter.isDone()) {
                cerr << "Nothing selected\n";
                return MS::kFailure;
        }
        MDagPath objectPath;
        MObject component;
        for ( ; !iter.isDone(); iter.next() ) {
                status = iter.getDagPath( objectPath, component );
                if (objectPath.hasFn(MFn::kNurbsSurface))
                        status = twistNurbsSurface(objectPath, component);
                else if (objectPath.hasFn(MFn::kMesh))
                        status = twistPolygon(objectPath, component);
                else {
                        cerr << "Selected object is not a NURBS surface or a polygon\n";
                        return MS::kFailure;
                }
        }
        return status;
}
MStatus initializePlugin( MObject obj )
{
        MStatus   status;
        MFnPlugin plugin( obj, PLUGIN_COMPANY, "3.0", "Any");
        status = plugin.registerCommand( "surfaceTwist", surfaceTwist::creator );
        if (!status) {
                status.perror("registerCommand");
                return status;
        }
        return status;
}
MStatus uninitializePlugin( MObject obj )
{
        MStatus   status;
        MFnPlugin plugin( obj );
        status = plugin.deregisterCommand( "surfaceTwist" );
        if (!status) {
                status.perror("deregisterCommand");
                return status;
        }
        return status;
}