whoops, I blame jesus for not adding this class

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9270 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

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

@@ -0,0 +1,50 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.jme3.terrain.geomipmap;
+
+import com.jme3.math.Vector3f;
+import com.jme3.renderer.Camera;
+import com.jme3.terrain.Terrain;
+import com.jme3.terrain.geomipmap.lodcalc.LodCalculator;
+import java.util.List;
+
+/**
+ * Updates grid offsets and cell positions.
+ * As well as updating LOD.
+ * 
+ * @author sploreg
+ */
+public class TerrainGridLodControl extends TerrainLodControl {
+    
+    public TerrainGridLodControl(Terrain terrain, Camera camera) {
+        super(terrain, camera);
+    }
+    
+    @Override
+    protected void updateLOD(List<Vector3f> locations, LodCalculator lodCalculator) {
+        TerrainGrid terrainGrid = (TerrainGrid)getSpatial();
+        
+        // for now, only the first camera is handled.
+        // to accept more, there are two ways:
+        // 1: every camera has an associated grid, then the location is not enough to identify which camera location has changed
+        // 2: grids are associated with locations, and no incremental update is done, we load new grids for new locations, and unload those that are not needed anymore
+        Vector3f cam = locations.isEmpty() ? Vector3f.ZERO.clone() : locations.get(0);
+        Vector3f camCell = terrainGrid.getCamCell(cam); // get the grid index value of where the camera is (ie. 2,1)
+        if (terrainGrid.cellsLoaded > 1) {                  // Check if cells are updated before updating gridoffset.
+            terrainGrid.gridOffset[0] = Math.round(camCell.x * (terrainGrid.size / 2));
+            terrainGrid.gridOffset[1] = Math.round(camCell.z * (terrainGrid.size / 2));
+            terrainGrid.cellsLoaded = 0;
+        }
+        if (camCell.x != terrainGrid.currentCamCell.x || camCell.z != terrainGrid.currentCamCell.z || !terrainGrid.runOnce) {
+            // if the camera has moved into a new cell, load new terrain into the visible 4 center quads
+            terrainGrid.updateChildren(camCell);
+            for (TerrainGridListener l : terrainGrid.listeners) {
+                l.gridMoved(camCell);
+            }
+        }
+        terrainGrid.runOnce = true;
+        super.updateLOD(locations, lodCalculator);
+    }
+}