fixed the terrain normal calc for the edges

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9584 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/terrain/com/jme3/terrain/geomipmap/TerrainQuad.java

@@ -1066,8 +1066,8 @@ public class TerrainQuad extends Node implements Terrain {
 
     public Vector3f getNormal(Vector2f xz) {
         // offset
-        float x = (float)(((xz.x - getWorldTranslation().x) / getWorldScale().x) + (float)totalSize / 2f);
-        float z = (float)(((xz.y - getWorldTranslation().z) / getWorldScale().z) + (float)totalSize / 2f);
+        float x = (float)(((xz.x - getWorldTranslation().x) / getWorldScale().x) + (float)(totalSize-1) / 2f);
+        float z = (float)(((xz.y - getWorldTranslation().z) / getWorldScale().z) + (float)(totalSize-1) / 2f);
         Vector3f normal = getNormal(x, z, xz);
         
         return normal;