Fixed NPE in water filter when setting the reflection mapsize before the filter has been initialized

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@10560 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core-effects/com/jme3/water/WaterFilter.java

@@ -853,10 +853,13 @@ public class WaterFilter extends Filter {
      */
     public void setReflectionMapSize(int reflectionMapSize) {
         this.reflectionMapSize = reflectionMapSize;
+        //if reflection pass is already initialized we must update it
+        if(reflectionPass !=  null){
             reflectionPass.init(renderManager.getRenderer(), reflectionMapSize, reflectionMapSize, Format.RGBA8, Format.Depth);
             reflectionCam.resize(reflectionMapSize, reflectionMapSize, true);
             reflectionProcessor.setReflectionBuffer(reflectionPass.getRenderFrameBuffer());
             material.setTexture("ReflectionMap", reflectionPass.getRenderedTexture());
+        }
 
     }