Fixed an ArrayIndexOutOfBound in animationFactory

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9246 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/animation/AnimationFactory.java

@@ -276,6 +276,7 @@ public class AnimationFactory {
         // if the delta of euler angles is higher than PI, we create intermediate keyframes
         // since we are using quaternions and slerp for rotation interpolation, we cannot interpolate over an angle higher than PI
         int prev = getPreviousKeyFrame(keyFrameIndex, keyFramesRotation);
+        if (prev != -1) {
             //previous rotation keyframe
             Rotation prevRot = keyFramesRotation[prev];
             //the maximum delta angle (x,y or z)
@@ -303,6 +304,7 @@ public class AnimationFactory {
                 }
 
             }
+        }
 
     }