added optional filter for getWorldExtends

This prevents including the ground, skybox and rootmesh

src/Helpers/babylon.environmentHelper.ts

@@ -476,7 +476,9 @@ module BABYLON {
                 return { groundSize, skyboxSize, rootPosition };
             }
 
-            const sceneExtends = this._scene.getWorldExtends();
+            const sceneExtends = this._scene.getWorldExtends((mesh) => {
+                return (mesh !== this._ground && mesh !== this._rootMesh && mesh !== this._skybox);
+            });
             const sceneDiagonal = sceneExtends.max.subtract(sceneExtends.min);
 
             if (this._options.sizeAuto) {

src/babylon.scene.ts

@@ -4230,16 +4230,15 @@
         }
 
         // Octrees
-        public getWorldExtends(): { min: Vector3; max: Vector3 } {
+        public getWorldExtends(filterPredicate?: (mesh: AbstractMesh) => boolean): { min: Vector3; max: Vector3 } {
             var min = new Vector3(Number.MAX_VALUE, Number.MAX_VALUE, Number.MAX_VALUE);
             var max = new Vector3(-Number.MAX_VALUE, -Number.MAX_VALUE, -Number.MAX_VALUE);
-            for (var index = 0; index < this.meshes.length; index++) {
-                var mesh = this.meshes[index];
-
+            filterPredicate = filterPredicate || (() => false);
+            this.meshes.filter(filterPredicate).forEach(mesh => {
                 mesh.computeWorldMatrix(true);
 
                 if (!mesh.subMeshes || mesh.subMeshes.length === 0 || mesh.infiniteDistance) {
-                    continue;
+                    return;
                 }
 
                 let boundingInfo = mesh.getBoundingInfo();
@@ -4249,7 +4248,7 @@
 
                 Tools.CheckExtends(minBox, min, max);
                 Tools.CheckExtends(maxBox, min, max);
-            }
+            })
 
             return {
                 min: min,