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# componentScaleManip.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.
    // ==========================================================================
    //+

    /*

        This example demonstrates the scale manipulator in the API.  This example
        uses three classes to accomplish this task: First, a context command
        (componentScaleContext) is provided to create instances of the context.
        Next, a custom selection context (ComponentScaleContext) is created to
        manage the component scale manipulator.   Finally, the component scale
        manipulator is provided as a custom node class.

        Loading and unloading:
        ----------------------

        The component scale manipulator context can be created
        with the following mel commands:

            componentScaleContext;
            setToolTo componentScaleContext1;

        If the preceding commands were used to create the manipulator context,
        the following commands can destroy it:

            deleteUI componentScaleContext1;
            deleteUI componentScaleManip;

        If the plugin is loaded and unloaded frequently (eg. during testing),
        it is useful to make these command sequences into shelf buttons.

        How to use:
        -----------

        Once the tool button has been created using the script above, select the
        tool button then select some object components.  If non-components are
        selected, warning messages will be printed indicating that no manipulatable
        objects are selected.  Once components are selected, the scale manipulator
        should appear at the centroid of the components.  Then the manipulator can
        be used much like the built-in scale manipulator.

        Currently this plugin only works correctly for nurbs surfaces where the
        parametization has distance 1.0 corresponding to the distance between CVs.
        This will be the case for nurbs spheres, torus, and cones.  Planes and
        cylinders do not have this property.

        Note that undo and redo are not supported in this example plugin.

    */

    #include <maya/MIOStream.h>
    #include <stdio.h>
    #include <stdlib.h>

    #include <maya/MFn.h>
    #include <maya/MPxNode.h>
    #include <maya/MPxManipContainer.h>
    #include <maya/MPxSelectionContext.h>
    #include <maya/MPxContextCommand.h>
    #include <maya/MModelMessage.h>
    #include <maya/MFnPlugin.h>
    #include <maya/MGlobal.h>
    #include <maya/MItSelectionList.h>
    #include <maya/MPoint.h>
    #include <maya/MVector.h>
    #include <maya/MDagPath.h>
    #include <maya/MManipData.h>
    #include <maya/MSelectionList.h>
    #include <maya/MItSurfaceCV.h>
    #include <maya/MFnComponent.h>

    // Manipulators
    #include <maya/MFnScaleManip.h>

    // This function is a utility that can be used to extract vector values from
    // plugs.
    //
    MVector vectorPlugValue(const MPlug& plug) {
        if (plug.numChildren() == 3)
        {
            double x,y,z;
            MPlug rx = plug.child(0);
            MPlug ry = plug.child(1);
            MPlug rz = plug.child(2);
            rx.getValue(x);
            ry.getValue(y);
            rz.getValue(z);
            MVector result(x,y,z);
            return result;
        }
        else {
            MGlobal::displayError("Expected 3 children for plug "+MString(plug.name()));
            MVector result(0,0,0);
            return result;
        }
    }

    //
    // componentScaleManip
    //
    // This class implements the component scaling example.
    //

    class componentScaleManip : public MPxManipContainer
    {
    public:
        componentScaleManip();
        virtual ~componentScaleManip();

        static void * creator();
        static MStatus initialize();
        virtual MStatus createChildren();
        virtual MStatus connectToDependNode(const MObject &node);

        virtual void draw(M3dView &view,
                          const MDagPath &path,
                          M3dView::DisplayStyle style,
                          M3dView::DisplayStatus status);

        void setSurfaceDagPath(const MDagPath& dagPath) {
            surfaceDagPath = dagPath;
        }

        void setComponentObject(const MObject& obj) {
            component = obj;
        }

        // Virtual handlers
        virtual MManipData manipToPlugConversion(unsigned index);
        virtual MManipData plugToManipConversion(unsigned index);

        MDagPath fScaleManip;

    public:
        static MTypeId id;

    private:

        MDagPath surfaceDagPath;
        MObject component;

        MPoint centroid;

        int numComponents;
        MPoint* initialPositions;
        MPoint* initialControlPoint;

        unsigned dummyPlugIndex;
    };

    MTypeId componentScaleManip::id( 0x80021 );

    componentScaleManip::componentScaleManip() : numComponents(0)
    ,   initialPositions(NULL)
    ,   initialControlPoint(NULL)
    {
        // The constructor must not call createChildren for user-defined
        // manipulators.
    }

    componentScaleManip::~componentScaleManip()
    {
        // initialPositions should always be either NULL or an allocated array
        // of MPoint.
        //
        delete [] initialPositions;
        delete [] initialControlPoint;
    }

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

    MStatus componentScaleManip::initialize()
    {
        MStatus stat;
        stat = MPxManipContainer::initialize();
        return stat;
    }

    MStatus componentScaleManip::createChildren()
    {
        MStatus stat = MStatus::kSuccess;

        fScaleManip = addScaleManip("scaleManip", "scale");

        return stat;
    }

    MStatus componentScaleManip::connectToDependNode(const MObject &node)
    {
        MStatus stat;

        MFnComponent componentFn(component);
        if (componentFn.elementCount() > numComponents)
        {
            delete [] initialPositions;
            delete [] initialControlPoint;
            numComponents = componentFn.elementCount();
            initialPositions = new MPoint[numComponents];
            initialControlPoint = new MPoint[numComponents];
        }

        // Iterate through the components, storing initial positions and find the
        // centroid.  Add manipToPlug callbacks for each component.
        //
        int i = 0;
        for (MItSurfaceCV iter(surfaceDagPath, component); !iter.isDone(); iter.next(), i++)
        {
            if (i >= numComponents)
            {
                MGlobal::displayWarning("More components found than expected.");
                break;
            }
            initialPositions[i] = iter.position(MSpace::kWorld);
            centroid += initialPositions[i];

            //
            // Create a manipToPlug callback that is invoked whenever the manipVal
            // changes.  The callback is added for every selected CV.
            //

            MFnDependencyNode nodeFn(node);
            MPlug controlPointArrayPlug = nodeFn.findPlug("controlPoints", &stat);
            if (controlPointArrayPlug.isNull())
            {
                MGlobal::displayError("Control point plug not found on node.");
                return MS::kFailure;
            }

            // The logical index from the component iterator is the same as the
            // logical index into the control points array.
            //
            MPlug controlPointPlug =
                controlPointArrayPlug.elementByLogicalIndex(iter.index(), &stat);
            if (controlPointPlug.isNull())
            {
                MGlobal::displayError("Control point element not found.");
                return MS::kFailure;
            }

            // Store the initial value of the control point.
            //
            initialControlPoint[i] = vectorPlugValue(controlPointPlug);

            unsigned plugIndex = addManipToPlugConversion(controlPointPlug);

            // Plug indices should be allocated sequentially, starting at 0.  Each
            // manip container will have its own set of plug indices.  This code
            // relies on the sequential allocation of indices, so trigger an error
            // if the indices are found to be different.
            //
            if (plugIndex != (unsigned)i)
            {
                MGlobal::displayError("Unexpected plug index returned.");
                return MS::kFailure;
            }
        }
        centroid = centroid / numComponents;

        MFnScaleManip scaleManip(fScaleManip);

        // Create a plugToManip callback that places the manipulator at the
        // centroid of the CVs.
        //
        addPlugToManipConversion(scaleManip.scaleCenterIndex());

        finishAddingManips();
        MPxManipContainer::connectToDependNode(node);
        return stat;
    }

    void componentScaleManip::draw(M3dView & view,
                         const MDagPath & path,
                         M3dView::DisplayStyle style,
                         M3dView::DisplayStatus status)
    {
        MPxManipContainer::draw(view, path, style, status);
    }

    MManipData componentScaleManip::plugToManipConversion(unsigned index) {
        MObject obj = MObject::kNullObj;

        // If we entered the callback with an invalid index, print an error and
        // return.  Since we registered the callback only for one index, all
        // invocations of the callback should be for that index.
        //
        MFnScaleManip scaleManip(fScaleManip);
        if (index == scaleManip.scaleCenterIndex())
        {
            // Set the center point for scaling to the centroid of the CV's.
            //
            MFnNumericData numericData;
            obj = numericData.create( MFnNumericData::k3Double );
            numericData.setData(centroid.x,centroid.y,centroid.z);

            return MManipData(obj);
        }

        MGlobal::displayError("Invalid index in plugToManipConversion()!");

        // For invalid indices, return vector of 0's
        MFnNumericData numericData;
        obj = numericData.create( MFnNumericData::k3Double );
        numericData.setData(0.0,0.0,0.0);

        return obj;
    }

    MManipData componentScaleManip::manipToPlugConversion(unsigned index) {
        MObject obj = MObject::kNullObj;

        MFnScaleManip scaleManip(fScaleManip);
        if (index < (unsigned)numComponents)
        {
            //
            // Now we need to determine the scaled position of the CV specified by
            // index.
            //

            MVector scaleVal;
            getConverterManipValue(scaleManip.scaleIndex(), scaleVal);

            // Determine the vector from the centroid to the CV
            //
            MVector positionVec = initialPositions[index] - centroid;

            // Scale the vector
            //
            MVector newPosition(positionVec.x*scaleVal.x,
                positionVec.y*scaleVal.y, positionVec.z*scaleVal.z);

            // Form the vector from the initial position to the new position.
            //
            newPosition = newPosition - positionVec;

            // Move the control point from the initial control point position along
            // the vector.  Control point positions are always measured relative to
            // the initial position of the control point, which is why a separate
            // array of control point positions is required.
            //
            newPosition += initialControlPoint[index];

            MFnNumericData numericData;
            obj = numericData.create( MFnNumericData::k3Double );
            numericData.setData(newPosition.x,newPosition.y,newPosition.z);

            return MManipData(obj);
        }

        // If we entered the handler with an invalid index, print an error and
        // return.  The callback should only be called for indices from 0 to
        // numComponents-1.
        //

        MGlobal::displayError("Invalid index in scale changed callback!");

        // For invalid indices, return vector of 0's
        MFnNumericData numericData;
        obj = numericData.create( MFnNumericData::k3Double );
        numericData.setData(0.0,0.0,0.0);

        return obj;

    }

    //
    // ComponentScaleContext
    //
    // This class is a simple context for supporting a scale manipulator.
    //

    class ComponentScaleContext : public MPxSelectionContext
    {
    public:
        ComponentScaleContext();
        virtual void    toolOnSetup(MEvent &event);
        virtual void    toolOffCleanup();

        // Callback issued when selection list changes
        static void updateManipulators(void * data);

    private:
        MCallbackId id1;
    };

    ComponentScaleContext::ComponentScaleContext()
    {
        MString str("Plugin component scaling manipulator");
        setTitleString(str);
    }

    void ComponentScaleContext::toolOnSetup(MEvent &)
    {
        MString str("Scale the selected components");
        setHelpString(str);

        updateManipulators(this);
        MStatus status;
        id1 = MModelMessage::addCallback(MModelMessage::kActiveListModified,
                                         updateManipulators,
                                         this, &status);
        if (!status) {
            MGlobal::displayError("Model addCallback failed");
        }
    }

    void ComponentScaleContext::toolOffCleanup()
    {
        MStatus status;
        status = MModelMessage::removeCallback(id1);
        if (!status) {
            MGlobal::displayError("Model remove callback failed");
        }
        MPxContext::toolOffCleanup();
    }

    void ComponentScaleContext::updateManipulators(void * data)
    {
        MStatus stat = MStatus::kSuccess;

        ComponentScaleContext * ctxPtr = (ComponentScaleContext *) data;
        ctxPtr->deleteManipulators();

        MSelectionList list;
        stat = MGlobal::getActiveSelectionList(list);
        MItSelectionList iter(list, MFn::kInvalid, &stat);

        if (MS::kSuccess == stat) {
            for (; !iter.isDone(); iter.next()) {

                // Make sure the selection list item is a dag path with components
                // before attaching the manipulator to it.
                //
                MDagPath dagPath;
                MObject components;
                iter.getDagPath(dagPath, components);

                if (components.isNull() || !components.hasFn(MFn::kComponent))
                {
                    MGlobal::displayWarning("Object in selection list is not "
                        "a component.");
                    continue;
                }

                // Add manipulator to the selected object
                //
                MString manipName ("componentScaleManip");
                MObject manipObject;
                componentScaleManip* manipulator =
                    (componentScaleManip *) componentScaleManip::newManipulator(manipName, manipObject);

                if (NULL != manipulator) {
                    // Add the manipulator
                    //
                    ctxPtr->addManipulator(manipObject);

                    // Connect the manipulator to the object in the selection list.
                    //
                    manipulator->setSurfaceDagPath(dagPath);
                    manipulator->setComponentObject(components);
                    if (!manipulator->connectToDependNode(dagPath.node()))
                    {
                        MGlobal::displayWarning("Error connecting manipulator to"
                            " object");
                    }
                }
            }
        }
    }

    //
    // componentScaleContext
    //
    // This is the command that will be used to create instances
    // of our context.
    //

    class componentScaleContext : public MPxContextCommand
    {
    public:
        componentScaleContext() {};
        virtual MPxContext * makeObj();

    public:
        static void* creator();
    };

    MPxContext *componentScaleContext::makeObj()
    {
        return new ComponentScaleContext();
    }

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

    //
    // The following routines are used to register/unregister
    // the context and manipulator
    //

    MStatus initializePlugin(MObject obj)
    {
        MStatus status;
        MFnPlugin plugin(obj, PLUGIN_COMPANY, "6.0", "Any");

        status = plugin.registerContextCommand("componentScaleContext",
                                               &componentScaleContext::creator);
        if (!status) {
            MGlobal::displayError("Error registering componentScaleContext command");
            return status;
        }

        status = plugin.registerNode("componentScaleManip", componentScaleManip::id,
                                     &componentScaleManip::creator, &componentScaleManip::initialize,
                                     MPxNode::kManipContainer);
        if (!status) {
            MGlobal::displayError("Error registering componentScaleManip node");
            return status;
        }

        return status;
    }

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

        status = plugin.deregisterContextCommand("componentScaleContext");
        if (!status) {
            MGlobal::displayError("Error deregistering componentScaleContext command");
            return status;
        }

        status = plugin.deregisterNode(componentScaleManip::id);
        if (!status) {
            MGlobal::displayError("Error deregistering componentScaleManip node");
            return status;
        }

        return status;
    }