[MISC] Enable back GsTaichi dynamic array mode by default except for MacOS. (#1977)

* Get around GsTaichi bug causing dof frictionloss to break on Apple Metal.
* Enable back GsTaichi dynamic array mode by default except for MacOS.

Author: duburcqa

genesis/__init__.py

@@ -118,8 +118,7 @@ def init(
 
     # Configure GsTaichi fast cache and array type
     global use_ndarray, use_fastcache
-    # is_ndarray_disabled = (os.environ.get("GS_ENABLE_NDARRAY") or ("0" if sys.platform == "darwin" else "1")) == "0"
-    is_ndarray_disabled = os.environ.get("GS_ENABLE_NDARRAY", "0") == "0"
+    is_ndarray_disabled = (os.environ.get("GS_ENABLE_NDARRAY") or ("0" if sys.platform == "darwin" else "1")) == "0"
     if use_ndarray is None:
         _use_ndarray = not (is_ndarray_disabled or performance_mode)
     else:

genesis/engine/solvers/rigid/constraint_solver_decomp.py

@@ -1067,7 +1067,11 @@ def add_frictionloss_constraints(
     n_dofs = dofs_state.ctrl_mode.shape[0]
 
     # TODO: sparse mode
-    ti.loop_config(serialize=ti.static(static_rigid_sim_config.para_level < gs.PARA_LEVEL.ALL))
+    # FIXME: The condition `if dofs_info.frictionloss[I_d] > EPS:` is not correctly evaluated on Apple Metal
+    # if `serialize=True`...
+    ti.loop_config(
+        serialize=ti.static(static_rigid_sim_config.para_level < gs.PARA_LEVEL.ALL and gs.backend != gs.metal)
+    )
     for i_b in range(_B):
         constraint_state.n_constraints_frictionloss[i_b] = 0
 

tests/test_rigid_physics.py

@@ -1754,6 +1754,10 @@ def test_set_dofs_frictionloss_physics(gs_sim, tol):
 @pytest.mark.required
 def test_frictionloss_advanced(show_viewer, tol):
     scene = gs.Scene(
+        viewer_options=gs.options.ViewerOptions(
+            camera_pos=(1.0, 0.25, 0.75),
+            camera_lookat=(0.0, 0.0, 0.0),
+        ),
         show_viewer=show_viewer,
         show_FPS=False,
     )