intersectOnNurbsSurfaceCmd.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:
//      A command which exercises the various NURBS intersect methods
//  available in the API. The command expects all data it needs to work
//  with to be on the selection list.
//
// Usage:
//      Before calling this command, the selection list needs to have
//      the following nodes selected in order:
//
//      o  A NURBS surface, such as nurbsPlaneShape1. The surface may
//         be transformed in the DAG, if desired.
//      o  The transform node of a locator. The user should place the
//         locator at the point in 3-space for which they want to find
//         the intersect on the NURBS surface.
//
//      When invoked with the above items in order on the selection list,
//      the command proceeds to calculate the intersect on the NURBS
//      surface, moving "locator2" to the computed intersect to allow
//      the user to visually see what intersect was calculated.
//
// Example:
//      1. Compile and load this plug-in into Maya.
//      2. Create a NURBS surface, such as a NURBS plane. Move some CVs
//         to obtain a wavy surface.
//      3. Create two locators, locator1 and locator2, (both should be
//         children of the world because the plug-in translates locator2
//         to the calculated closest intersect value for display purposes).
//      4. Position the first locator somewhere in 3D space over the
//         surface.
//      5. Position the second locator so that the line that passes through
//         both locators intersects the NURBS surface. Note that the second
//         locator will be automatically moved to the closest intersect on the
//         surface by the command.
//      5. Select the two objects:
//              MEL> select nurbsPlaneShape1 locator1 locator2;
//      6. Invoke this command:
//              MEL> intersectOnNurbsSurface;
//      7. You should see locator2 move to the point on the NURBS
//         surface which is closest to locator1.
//      8. Move locator1 and locator2 to different positions and invoke this
//         command again. You should see locator2 move to the correct
//         closest intersect each time.
//      9. Try rotating, scaling and translating the NURBS surface's
//         transform node and you should see the intersect being
//         correctly computed.
//

#include <math.h>

// MAYA HEADERS
#include <maya/MIOStream.h>
#include <maya/MArgList.h>
#include <maya/MPxCommand.h>
#include <maya/MGlobal.h>
#include <maya/MSelectionList.h>
#include <maya/MPoint.h>
#include <maya/MNurbsIntersector.h>
#include <maya/MDagPath.h>
#include <maya/MMatrix.h>
#include <maya/MFnDagNode.h>
#include <maya/MFnTransform.h>
#include <maya/MVector.h>
#include <maya/MFnPlugin.h>
#include <maya/MFnNurbsSurface.h>

#include "intersectOnNurbsSurfaceCmd.h"

// CONSTRUCTOR:
intersectOnNurbsSurfaceCmd::intersectOnNurbsSurfaceCmd()
{
}

// DESTRUCTOR:
intersectOnNurbsSurfaceCmd::~intersectOnNurbsSurfaceCmd()
{
}

// FOR CREATING AN INSTANCE OF THIS COMMAND:
void* intersectOnNurbsSurfaceCmd::creator()
{
   return new intersectOnNurbsSurfaceCmd;
}

// MAKE THIS COMMAND NOT UNDOABLE:
bool intersectOnNurbsSurfaceCmd::isUndoable() const
{
   return false;
}


MStatus intersectOnNurbsSurfaceCmd::doIt(const MArgList& args)
// Description:
// See the command usage at the top of this file for details
// on how to use this command.
//
{
    bool debug = false; 
    bool treeBased = true;

    MStatus stat = MStatus::kSuccess;

    if(debug) cout << "intersectOnNurbsSurfaceCmd::doIt\n";
    
    MSelectionList list;
    stat = MGlobal::getActiveSelectionList(list);
    if(!stat) {
        if(debug) cout << "getActiveSelectionList FAILED\n";
        return( stat );
    }

    MDagPath path;

    MObject nurbsObject;
    stat = list.getDependNode(0,nurbsObject);
    if(!stat)
        if(debug) cout << "getDependNode FAILED\n";

    MFnDagNode nodeFn(nurbsObject);

    // don't use the transform, use the shape
    if(nodeFn.childCount() > 0) {
        MObject child = nodeFn.child(0);
        nodeFn.setObject(child);
    }

    list.getDagPath(0,path);
    if(debug) cout << "Working with: " << path.partialPathName() << endl;

    MMatrix mat = path.inclusiveMatrixInverse();
    if(debug) cout << mat << endl;

    MObject loc1Object;
    stat = list.getDependNode(1, loc1Object); // use the transform, not the shape
    if(!stat) {
        if(debug) cout << "FAILED grabbing locator1\n";
        return( stat );
    }

    MObject loc2Object;
    stat = list.getDependNode(2, loc2Object); // use the transform, not the shape
    if(!stat) {
        if(debug) cout << "FAILED grabbing locator2\n";
        return( stat );
    }

    MFnTransform loc1Fn(loc1Object);
    MVector t = loc1Fn.getTranslation(MSpace::kObject);

    MFnTransform loc2Fn(loc2Object);
    MVector t2 = loc2Fn.getTranslation(MSpace::kObject);

    MVector ray = t2 - t;
    
    MPoint pt(t[0], t[1], t[2]);
    if(debug) cout << "test point: " << pt << endl;
    if(debug) cout << "transformed:" << pt * mat << endl;
    MPoint resultPoint;
    double u=0, v=0;

    if ( treeBased ) {
        // Use the tree-based NURBS intersect algorithm.
        // The idea is to call create() once, then reuse for later calls
        // to getIntersect(). In our example, we'll just do one
        // getIntersect() call.
        //
        if(debug) cout << "tree-based NURBS intersect (MNurbsIntersector)\n";
        MNurbsIntersector nurbIntersect;
        stat = nurbIntersect.create(nurbsObject, mat);
        if(!stat) {
            if(debug) cout << "MNurbsIntersector::create FAILED\n";
            return( stat );
        }

        stat = nurbIntersect.getIntersect(pt, ray, u, v, resultPoint, kMFnNurbsEpsilon);
        if(!stat) {
            if(debug) cout << "MNurbsIntersector::getIntersect FAILED!\n";
            return( stat );
        }

    } else {
        // Use the non-tree NURBS intersect algorithm from MFnNurbsSurface.
        //
        MFnNurbsSurface ns( nurbsObject );
        pt *= mat;  // Need to transform into object space ourselves
        bool result = ns.intersect(pt, ray, u, v, resultPoint, kMFnNurbsEpsilon, MSpace::kObject, false, NULL, false, NULL, &stat );
        if(!result || !stat) {
            if(debug) cout << "MFnNurbsSurface::intersect FAILED!\n";
            if(stat) {
                stat = MStatus::kFailure;
            }
            return( stat );
        }
    }

    // As a check, grab the world space point that corresponds to the
    // UVs returned from getIntersect.
    //
    if(debug) cout << "result UV: " << u << ", " << v << endl;
    MString cmd = "pointOnSurface -u ";
    cmd += u;
    cmd += " -v ";
    cmd += v;
    cmd += " ";
    cmd += path.partialPathName();
    MDoubleArray arr;
    MGlobal::executeCommand(cmd, arr); 
    if(debug) cout << "check results:  result UV corresponds to world point: " << arr << endl;

    MPoint worldResultPoint = resultPoint * path.inclusiveMatrix();
    if(debug) cout << "local space result point: " << resultPoint << endl;
    if(debug) cout << "world space result point: " << worldResultPoint << endl;

    if ( fabs( arr[0] - worldResultPoint.x ) > 0.0001
            || fabs( arr[1] - worldResultPoint.y ) > 0.0001
            || fabs( arr[2] - worldResultPoint.z ) > 0.0001 ) {
        cout << "check results: pointOnSurface does not match world point: " << arr << endl;
        return( MS::kFailure );
    }

    // Move the second locator to the returned world-space point
    // This should always be on the nurbs surface.
    // Note: we are assuming with both locators that they are children of
    // the world.
    //
    stat = loc2Fn.setTranslation(worldResultPoint, MSpace::kTransform);

    return stat;
}

// UNDO THE COMMAND
MStatus intersectOnNurbsSurfaceCmd::undoIt()
{
    MStatus status;
    // undo not implemented
    return status;
}

//
// The following routines are used to register/unregister
// the command we are creating within Maya
//
MStatus initializePlugin( MObject obj )
{
    MStatus   status;
    MFnPlugin plugin( obj, PLUGIN_COMPANY, "8.5", "Any");

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

    return status;
}

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

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

    return status;
}