diff --git a/engine b/engine
index ed87f29..baac333 160000
--- a/engine
+++ b/engine
@@ -1 +1 @@
-Subproject commit ed87f292ffa3cf89903cddcdec396115893f7d66
+Subproject commit baac333b44118e17e46f85fc8637aa5ff7f519fc
diff --git a/game/batch.py b/game/batch.py
index b3612fc..527d7a2 100644
--- a/game/batch.py
+++ b/game/batch.py
@@ -13,54 +13,70 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from ctypes import c_ubyte, c_uint, c_void_p, addressof
+from ctypes import c_ubyte, c_uint, c_void_p, POINTER, addressof
 
 from engine import (
     buffer, INSTANCE_FLAG_SPAWNED, BATCH_MAX_SIZE, param_type, params_format,
     create_batch, fill_batch, draw_batch, destroy_batch)
 
+_c_ubyte_p = POINTER(c_ubyte)
+_c_uint_p = POINTER(c_uint)
+
 class Batch:
-    __slots__ = '_batch', '_static', 'vertices', 'size', 'max_size', 'flags', 'meshes', 'params', '_params', '__dict__'
+    __slots__ = ('_batch', 'vertices', 'max_size', 'size',
+        'flags', '_flags', 'mesh', '_meshes', 'param', '_params', '_name', '__dict__')
 
     def __init__(self, vertices, max_size, max_meshes, **params_decls):
         assert max_size <= BATCH_MAX_SIZE
         nparams = len(params_decls)
-        names = params_decls.keys()
-        formats = params_decls.values()
-        self._batch = create_batch(vertices._vertices, max_size, max_meshes, params_format(*formats))
-        self._static = False
-        self.vertices = vertices
-        self.size = 0
-        self.max_size = max_size
-        self.flags = buffer(c_ubyte, max_size)
-        self.meshes = buffer(c_uint, max_size)
-        self.params = tuple(map(lambda f: buffer(param_type(f), max_size), formats))
         if nparams:
-            self._params = (c_void_p * nparams)(*map(addressof, self.params))
+            self._batch = create_batch(vertices._vertices, max_size, max_meshes, params_format(*params_decls.values()))
         else:
+            self._batch = create_batch(vertices._vertices, max_size, max_meshes, None)
+        self.vertices = vertices
+        self.max_size = max_size
+        self.size = 0
+        self.flags = buffer(c_ubyte, max_size)
+        self._flags = _c_ubyte_p(self.flags)
+        self.mesh = buffer(c_uint, max_size)
+        self._meshes = _c_uint_p(self.mesh)
+        if nparams:
+            self.param = tuple(map(lambda f: buffer(param_type(f), max_size), params_decls.values()))
+            self._params = (c_void_p * nparams)(*map(addressof, self.param))
+            self._name = dict(zip(params_decls.keys(), range(nparams)))
+            for name, value in zip(params_decls.keys(), self.param):
+                setattr(self, name, value)
+        else:
+            self.param = None
             self._params = None
-        for name, value in zip(names, self.params):
-            setattr(self, name, value)
+            self._name = None
 
     def __del__(self):
         destroy_batch(self._batch)
 
-    def spawn(self, model, *params):
-        assert len(params) == len(self.params)
+    def spawn(self, flags, mesh, **params):
         index = self.size
         assert index < self.max_size
-        self.flags[index] = model.flags | INSTANCE_FLAG_SPAWNED
-        self.meshes[index] = model.mesh
-        for self_params, param in zip(self.params, params):
-            self_params[index] = param
+        self.flags[index] = flags | INSTANCE_FLAG_SPAWNED
+        self.mesh[index] = mesh
+        for name, value in params.items():
+            getattr(self, name)[index] = value
         self.size += 1
         return index
 
-    def make_static(self):
-        fill_batch(self._batch, self.size, self.flags, self.meshes, self._params)
-        self._static = True
+    def freeze(self, flags = None, mesh = None, **params):
+        if flags is not None:
+            self._flags = None if flags else _c_ubyte_p(self.flags)
+        if mesh is not None:
+            self._meshes = None if mesh else _c_uint_p(self.mesh)
+        for name, value in params.items():
+            if value is not None:
+                index = self._name[name]
+                self._params[index] = None if value else addressof(self.param[index])
+
+    def fill(self):
+        fill_batch(self._batch, self.size, self._flags, self._meshes, self._params)
 
     def draw(self):
-        if not self._static:
-            fill_batch(self._batch, self.size, self.flags, self.meshes, self._params)
+        fill_batch(self._batch, self.size, self._flags, self._meshes, self._params)
         draw_batch(self._batch)
diff --git a/game/entity.py b/game/entity.py
index dcf49c4..e7604a0 100644
--- a/game/entity.py
+++ b/game/entity.py
@@ -16,5 +16,5 @@
 class Entity:
     __slots__ = 'index'
 
-    def __init__(self, batch, model, *params):
-        self.index = batch.spawn(model, *params)
+    def __init__(self, batch, flags, mesh, **params):
+        self.index = batch.spawn(flags, mesh, **params)
diff --git a/game/game.py b/game/game.py
index cfca321..82a1e2a 100644
--- a/game/game.py
+++ b/game/game.py
@@ -76,7 +76,7 @@ class TestEntity(Entity):
     __slots__ = 'translation', 'orientation', 'spawn_translation', 'spawn_orientation'
 
     def __init__(self, batch, model, translation, orientation):
-        Entity.__init__(self, batch, model, translation, orientation)
+        Entity.__init__(self, batch, model.flags, model.mesh, translation = translation, orientation = orientation)
         self.translation = batch.translation[self.index]
         self.orientation = batch.orientation[self.index]
         self.spawn_translation = translation
@@ -165,8 +165,10 @@ def create_scene(keyboard, mouse):
             model = mud_model
         else:
             model = rock_model
-        tiles_batch.spawn(model, vec3(float(((mx - 128) * 8) + 4), float(((127 - my) * 8) + 4), 0.0))
-    tiles_batch.make_static()
+        tiles_batch.spawn(model.flags, model.mesh,
+            translation = vec3(float(((mx - 128) * 8) + 4), float(((127 - my) * 8) + 4), 0.0))
+    tiles_batch.fill()
+    tiles_batch.freeze(flags = True, mesh = True, translation = True)
 
     tests_texture = Texture(*archive.get_texture('tests'))
     tests_vertices = Vertices(*archive.get_vertices('tests'))
@@ -179,9 +181,11 @@ def create_scene(keyboard, mouse):
     blob_forward = math.vec3_normalize((sun_direction[0], sun_direction[1], 0.0))
     blob_right = math.vec3_cross(blob_forward, math.vec3_up)
     blob_orientation = mat3(vec3(*blob_right), vec3(*blob_forward), vec3_up)
-    blob = TestEntity(tests_batch, blob_model, vec3(-100.0, -500.0, 0.0), blob_orientation)
-    cube = TestEntity(tests_batch, cube_model, vec3(100.0, -500.0, 0.0), mat3_identity)
-    clouds = TestEntity(tests_batch, clouds_model, vec3(0.0, 0.0, 32.0), mat3_identity)
+    blob = TestEntity(tests_batch, blob_model, translation = vec3(-100.0, -500.0, 0.0), orientation = blob_orientation)
+    cube = TestEntity(tests_batch, cube_model, translation = vec3(100.0, -500.0, 0.0), orientation = mat3_identity)
+    clouds = TestEntity(tests_batch, clouds_model, translation = vec3(0.0, 0.0, 32.0), orientation = mat3_identity)
+    tests_batch.fill()
+    tests_batch.freeze(flags = True, mesh = True)
 
     sea_polar_textures = sea.load_polar_textures(('data/sea_bump1.png', 'data/sea_bump2.png'))
     sea_detail_texture = sea.load_detail_texture('data/sea_bump.png')