added grass painting

Rendering/RenderableCache.cs

@@ -195,6 +195,14 @@ namespace CodeWalker.Rendering
             }
         }
 
+        public void Invalidate(YmapGrassInstanceBatch batch)
+        {
+            lock (updateSyncRoot)
+            {
+                instbatches.Invalidate(batch);
+            }
+        }
+
 
     }
 

Rendering/Renderer.cs

@@ -380,6 +380,11 @@ namespace CodeWalker.Rendering
             renderableCache.Invalidate(path);
         }
 
+        public void Invalidate(YmapGrassInstanceBatch batch)
+        {
+            renderableCache.Invalidate(batch);
+        }
+
 
         public void UpdateSelectionDrawFlags(DrawableModel model, DrawableGeometry geom, bool rem)
         {

Rendering/Shaders/BasicShader.cs

@@ -695,6 +695,10 @@ namespace CodeWalker.Rendering
         {
             var gb = batch.Key;
 
+            // sanity check
+            if (batch.GrassInstanceBuffer == null)
+                return;
+
             VSEntityVars.Vars.CamRel = new Vector4(gb.CamRel, 0.0f);
             VSEntityVars.Vars.Orientation = Quaternion.Identity;
             VSEntityVars.Vars.Scale = Vector3.One;