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# lineManip.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.
    // ==========================================================================
    //+

    //
    //  lineManip.cpp
    //      Creates manipulator node lineManip
    //      Creates command lineManipCmd
    //
    //  This example demonstrates how to use the MPxManipulatorNode
    //  class along with a command to create a user defined
    //  manipulator.  The manipulator created is a simple line
    //  which is an OpenGL pickable component.  As you
    //  move the pickable component, selected transforms have
    //  their scale attribute modified. The line's movements
    //  are restricted in a plane.
    //  A corresponding command is used to create and delete
    //  the manipulator node and to support undo/redo etc.

    /*

    // To show this example using MEL, run the following:
    loadPlugin lineManip.so;
    lineManipCmd -create;

    // To delete the manipulator using MEL:
    lineManipCmd -delete;

    */

    #include "lineManip.h"

    #include <maya/MHardwareRenderer.h>
    #include <maya/MIOStream.h>
    #include <maya/MMatrix.h>
    #include <maya/MPoint.h>
    #include <maya/MVector.h>
    #include <maya/MSelectionList.h>
    #include <maya/MItSelectionList.h>
    #include <maya/MFnTransform.h>
    #include <maya/MGlobal.h>
    #include <maya/MFnCamera.h>
    #include <maya/MTemplateCommand.h>

    // Statics
    MTypeId lineManip::id( 0x81047 );

    // Utility class for returning line points
    class lineGeometry
    {
    public:
        static MPoint topPoint() {
            return MPoint( 1.0f, 1.0f, 0.0f );
        }
        static MPoint bottomPoint() {
            return MPoint( 1.0f, -1.0f, 0.0f );
        }
        static MPoint otherPoint() {
            return MPoint( 2.0f, -1.0f, 0.0f );
        }
    };

    //
    // class implementation
    //
    lineManip::lineManip()
    {
        // Setup the plane with a point on the
        // plane along with a normal
        MPoint pointOnPlane(lineGeometry::topPoint());
        // Normal = cross product of two vectors on the plane
        MVector normalToPlane = (MVector(lineGeometry::topPoint()) - MVector(lineGeometry::otherPoint())) ^
                        (MVector(lineGeometry::otherPoint()) - MVector(lineGeometry::bottomPoint()));
        // Necessary to normalize
        normalToPlane.normalize();
        // Plane defined by a point and a normal
        plane.setPlane( pointOnPlane, normalToPlane );
    }

    lineManip::~lineManip()
    {
        // No-op
    }

    // virtual
    void lineManip::draw(M3dView &view, const MDagPath &path,
                    M3dView::DisplayStyle style, M3dView::DisplayStatus status)
    {
        // Initialize GL function table first time through
        static MGLFunctionTable *gGLFT = 0;
        if ( 0 == gGLFT )
            gGLFT = MHardwareRenderer::theRenderer()->glFunctionTable();

        // Are we in the right view
        MDagPath dpath;
        view.getCamera(dpath);
        MFnCamera viewCamera(dpath);
        const char *nameBuffer = viewCamera.name().asChar();
        if ( 0 == nameBuffer )
            return;
        if ( ( 0 == strstr(nameBuffer,"persp") ) && ( 0 == strstr(nameBuffer,"front") ) )
            return;

        // Populate the point arrays which are in local space
        float top[4],bottom[4];
        lineGeometry::topPoint().get(top);
        lineGeometry::bottomPoint().get(bottom);

        // Depending on what's active, we modify the
        // end points with mouse deltas in local
        // space
        MGLuint active = 0;
        if ( glActiveName( active ) )
        {
            float *a = 0,*b = 0;
            if ( active == lineName )
            {
                a = &top[0]; b = &bottom[0];
            }

            if ( active != 0 )
            {
                a[0] += (float) mousePointGlName.x; a[1] += (float) mousePointGlName.y; a[2] += (float) mousePointGlName.z;
                b[0] += (float) mousePointGlName.x; b[1] += (float) mousePointGlName.y; b[2] += (float) mousePointGlName.z;
            }
        }

        // Begin the drawing
        view.beginGL();

        // Get the starting value of the pickable items
        MGLuint glPickableItem;
        glFirstHandle( glPickableItem );

        // Top
        lineName = glPickableItem;
        // Place before you draw the manipulator component that can
        // be pickable.
        colorAndName( view, glPickableItem, true, mainColor() );
        gGLFT->glBegin( MGL_LINES );
            gGLFT->glVertex3fv( top );
            gGLFT->glVertex3fv( bottom );
        gGLFT->glEnd();

        // End the drawing
        view.endGL();
    }

    // virtual
    MStatus lineManip::doPress( M3dView& view )
    {
        // Reset the mousePoint information on
        // a new press
        mousePointGlName = MPoint::origin;
        updateDragInformation();
        return MS::kSuccess;
    }

    // virtual
    MStatus lineManip::doDrag( M3dView& view )
    {
        updateDragInformation();
        return MS::kSuccess;
    }

    // virtual
     MStatus lineManip::doRelease( M3dView& view )
    {
        // Scale nodes on the selection list.
        // Simple implementation that does not
        // support undo.
        MSelectionList list;
        MGlobal::getActiveSelectionList( list );
        for ( MItSelectionList iter( list ); !iter.isDone(); iter.next() )
        {
            MObject node;
            MStatus status;
                iter.getDependNode( node );
            MFnTransform xform( node, &status );
            if ( MS::kSuccess == status )
            {
                double newScale[3];
                newScale[0] = mousePointGlName.x + 1;
                newScale[1] = mousePointGlName.y + 1;
                newScale[2] = mousePointGlName.z + 1;
                xform.setScale( newScale );
            }
        }
        return MS::kSuccess;
    }

    MStatus lineManip::updateDragInformation()
    {
        // Find the mouse point in local space
        MPoint localMousePoint;
        MVector localMouseDirection;
        if ( MS::kFailure == mouseRay( localMousePoint, localMouseDirection) )
            return MS::kFailure;

        // Find the intersection of the mouse point with the
        // manip plane
        MPoint mouseIntersectionWithManipPlane;
        if ( ! plane.intersect( localMousePoint, localMouseDirection,   mouseIntersectionWithManipPlane ) )
            return MS::kFailure;

        mousePointGlName = mouseIntersectionWithManipPlane;

        MGLuint active = 0;
        if ( glActiveName( active ) )
        {
            float start[4],end[4];
            if ( active == lineName )
            {
                lineGeometry::topPoint().get(start);
                lineGeometry::bottomPoint().get(end);
            }

            if ( active != 0 )
            {
                lineMath line;
                // Find a vector on the plane
                MPoint a( start[0], start[1], start[2] );
                MPoint b( end[0], end[1], end[2] );
                MPoint vab = a - b;
                // Define line with a point and a vector on the plane
                line.setLine( start, vab );
                MPoint cpt;
                // Find the closest point so that we can get the
                // delta change of the mouse in local space
                if ( line.closestPoint( mousePointGlName, cpt ) )
                {
                    mousePointGlName.x -= cpt.x;
                    mousePointGlName.y -= cpt.y;
                    mousePointGlName.z -= cpt.z;
                }
            }
        }
        return MS::kFailure;
    }

    //
    // Template command that creates and deletes the manipulator
    //

    class lineManipCmd;
    char cmdName[] = "lineManipCmd";
    char nodeName[] = "simpleLineManip"; // lineManip already taken

    class lineManipCmd : public MTemplateCreateNodeCommand<lineManipCmd,cmdName,nodeName>
    {
    public:
        //
        lineManipCmd()
        {}
    };

    static lineManipCmd _lineManipCmd;

    //
    // Static methods
    //
    void* lineManip::creator()
    {
        return new lineManip();
    }

    MStatus lineManip::initialize()
    {
        return MS::kSuccess;
    }

    //
    //  Entry points
    //

    MStatus initializePlugin( MObject obj )
    {
        MStatus   status;
        MFnPlugin plugin( obj, PLUGIN_COMPANY, "2009", "Any");

        status = plugin.registerNode( nodeName, lineManip::id, lineManip::creator,
            lineManip::initialize, MPxNode::kManipulatorNode );
        if (!status)
        {
            status.perror("registerNode");
            return status;
        }

        status = _lineManipCmd.registerCommand( obj );
        if (!status)
        {
            status.perror("registerCommand");
            return status;
        }

        return status;
    }

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

        status = plugin.deregisterNode( lineManip::id );
        if (!status)
        {
            status.perror("deregisterNode");
            return status;
        }
        status = _lineManipCmd.deregisterCommand( obj );
        if (!status)
        {
            status.perror("deregisterCommand");
            return status;
        }

        return status;
    }