Something is wacky with PathUtil.computeRotation, but I can't figure out

what.  Having tried various tweaks with no success, I finally punted and 
changed LineSegmentPath to use computeAxisRotation.  I also fixed the 
order of cross products in that method and got rid of a redundant cross 
product.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3761 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/jme/sprite/LineSegmentPath.java

@@ -48,6 +48,7 @@ public class LineSegmentPath extends Path
         _orient = orient;
         _points = points;
         _durations = durations;
+        PathUtil.computeRotation(up, orient, Vector3f.UNIT_X, _prerot);
         updateRotation();
     }
 
@@ -89,7 +90,8 @@ public class LineSegmentPath extends Path
     protected void updateRotation ()
     {
         _points[_current+1].subtract(_points[_current], _temp);
-        PathUtil.computeRotation(_up, _orient, _temp, _rotate);
+        PathUtil.computeAxisRotation(_up, _temp, _rotate);
+        _rotate.multLocal(_prerot);
         _sprite.getLocalRotation().set(_rotate);
     }
 
@@ -99,5 +101,6 @@ public class LineSegmentPath extends Path
     protected float _accum;
     protected int _current;
     protected Vector3f _temp = new Vector3f(0, 0, 0);
-    protected Quaternion _rotate = new Quaternion();
+    protected Quaternion _prerot = new Quaternion(),
+        _rotate = new Quaternion();
 }

src/java/com/threerings/jme/sprite/PathUtil.java

@@ -44,10 +44,9 @@ public class PathUtil
     {
         _axes[0].set(orient);
         _axes[0].normalizeLocal();
-        _axes[0].cross(up, _axes[1]);
+        up.cross(_axes[0], _axes[1]);
         _axes[1].normalizeLocal();
-        _axes[1].cross(_axes[0], _axes[2]);
+        _axes[0].cross(_axes[1], _axes[2]);
-        _axes[2].cross(_axes[0], _axes[1]);
         target.fromAxes(_axes);
         return target;
     }