Allows physics reset during simulation (#259)

- Allows users to exit on 1 Ctrl+C instead of consecutive 2 key strokes.
- Allows physics reset during simulation.

Example:

**env.sim.reset() # resets physics simulation
env.seed(seed) # ensures running with the same seed
env.reset()**

<!-- As a practice, it is recommended to open an issue to have
discussions on the proposed pull request.
This makes it easier for the community to keep track of what is being
developed or added, and if a given feature
is demanded by more than one party. -->

- New feature (non-breaking change which adds functionality)

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

source/isaaclab/docs/CHANGELOG.rst

@@ -44,14 +44,11 @@ Fixed
 0.36.2 (2025-03-12)
 ~~~~~~~~~~~~~~~~~~~
 
-Added
-^^^^^
+Changed
+^^^^^^^
 
-* Added a new event mode called "prestartup", which gets called right after the scene design is complete
-  and before the simulation is played.
-* Added a callback to resolve the scene entity configurations separately once the simulation plays,
-  since the scene entities cannot be resolved before the simulation starts playing
-  (as we currently rely on PhysX to provide us with the joint/body ordering)
+* Allowed users to exit on 1 Ctrl+C instead of consecutive 2 key strokes.
+* Allowed physics reset during simulation through :meth:`reset` in :class:`~isaaclab.sim.SimulationContext`.
 
 
 0.36.1 (2025-03-10)
@@ -118,6 +115,19 @@ Changed
   * ``set_fixed_tendon_limit`` → ``set_fixed_tendon_position_limit``
 
 
+0.34.13 (2025-03-06)
+~~~~~~~~~~~~~~~~~~~~
+
+Added
+^^^^^
+
+* Added a new event mode called "prestartup", which gets called right after the scene design is complete
+  and before the simulation is played.
+* Added a callback to resolve the scene entity configurations separately once the simulation plays,
+  since the scene entities cannot be resolved before the simulation starts playing
+  (as we currently rely on PhysX to provide us with the joint/body ordering)
+
+
 0.34.12 (2025-03-06)
 ~~~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/app/app_launcher.py

@@ -117,9 +117,24 @@ class AppLauncher:
         # Hide the stop button in the toolbar
         self._hide_stop_button()
 
+        # Hide play button callback if the timeline is stopped
+        import omni.timeline
+
+        self._hide_play_button_callback = (
+            omni.timeline.get_timeline_interface()
+            .get_timeline_event_stream()
+            .create_subscription_to_pop_by_type(
+                int(omni.timeline.TimelineEventType.STOP), lambda e: self._hide_play_button(True)
+            )
+        )
+        self._unhide_play_button_callback = (
+            omni.timeline.get_timeline_interface()
+            .get_timeline_event_stream()
+            .create_subscription_to_pop_by_type(
+                int(omni.timeline.TimelineEventType.PLAY), lambda e: self._hide_play_button(False)
+            )
+        )
         # Set up signal handlers for graceful shutdown
-        # -- during interrupts
-        signal.signal(signal.SIGINT, self._interrupt_signal_handle_callback)
         # -- during explicit `kill` commands
         signal.signal(signal.SIGTERM, self._abort_signal_handle_callback)
         # -- during segfaults
@@ -796,12 +811,22 @@ class AppLauncher:
                 play_button_group._stop_button.enabled = False  # type: ignore
                 play_button_group._stop_button = None  # type: ignore
 
-    def _interrupt_signal_handle_callback(self, signal, frame):
-        """Handle the interrupt signal from the keyboard."""
-        # close the app
-        self._app.close()
-        # raise the error for keyboard interrupt
-        raise KeyboardInterrupt
+    def _hide_play_button(self, flag):
+        """Hide/Unhide the play button in the toolbar.
+
+        This is used if the timeline is stopped by a GUI action like "save as" to not allow the user to
+        resume the timeline afterwards.
+        """
+        # when we are truly headless, then we can't import the widget toolbar
+        # thus, we only hide the play button when we are not headless (i.e. GUI is enabled)
+        if self._livestream >= 1 or not self._headless:
+            import omni.kit.widget.toolbar
+
+            toolbar = omni.kit.widget.toolbar.get_instance()
+            play_button_group = toolbar._builtin_tools._play_button_group  # type: ignore
+            if play_button_group is not None:
+                play_button_group._play_button.visible = not flag  # type: ignore
+                play_button_group._play_button.enabled = not flag  # type: ignore
 
     def _abort_signal_handle_callback(self, signal, frame):
         """Handle the abort/segmentation/kill signals."""

source/isaaclab/isaaclab/assets/articulation/articulation.py

@@ -16,6 +16,7 @@ from typing import TYPE_CHECKING
 import isaacsim.core.utils.stage as stage_utils
 import omni.log
 import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import PhysxSchema, UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -1144,9 +1145,8 @@ class Articulation(AssetBase):
     """
 
     def _initialize_impl(self):
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # obtain the first prim in the regex expression (all others are assumed to be a copy of this)
         template_prim = sim_utils.find_first_matching_prim(self.cfg.prim_path)
         if template_prim is None:
@@ -1301,8 +1301,6 @@ class Articulation(AssetBase):
         """Invalidates the scene elements."""
         # call parent
         super()._invalidate_initialize_callback(event)
-        # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._root_physx_view = None
 
     """

source/isaaclab/isaaclab/assets/articulation/articulation_data.py

@@ -8,6 +8,7 @@ import weakref
 
 import omni.log
 import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 
 import isaaclab.utils.math as math_utils
 from isaaclab.utils.buffers import TimestampedBuffer
@@ -48,9 +49,8 @@ class ArticulationData:
         # Set initial time stamp
         self._sim_timestamp = 0.0
 
-        # Obtain global physics sim view
-        self._physics_sim_view = physx.create_simulation_view("torch")
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         gravity = self._physics_sim_view.get_gravity()
         # Convert to direction vector
         gravity_dir = torch.tensor((gravity[0], gravity[1], gravity[2]), device=self.device)

source/isaaclab/isaaclab/assets/asset_base.py

@@ -14,6 +14,7 @@ from typing import TYPE_CHECKING, Any
 
 import omni.kit.app
 import omni.timeline
+from isaacsim.core.simulation_manager import SimulationManager
 
 import isaaclab.sim as sim_utils
 
@@ -255,12 +256,8 @@ class AssetBase(ABC):
             called whenever the simulator "plays" from a "stop" state.
         """
         if not self._is_initialized:
-            # obtain simulation related information
-            sim = sim_utils.SimulationContext.instance()
-            if sim is None:
-                raise RuntimeError("SimulationContext is not initialized! Please initialize SimulationContext first.")
-            self._backend = sim.backend
-            self._device = sim.device
+            self._backend = SimulationManager.get_backend()
+            self._device = SimulationManager.get_physics_sim_device()
             # initialize the asset
             self._initialize_impl()
             # set flag

source/isaaclab/isaaclab/assets/deformable_object/deformable_object.py

@@ -11,6 +11,7 @@ from typing import TYPE_CHECKING
 
 import omni.log
 import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import PhysxSchema, UsdShade
 
 import isaaclab.sim as sim_utils
@@ -261,9 +262,8 @@ class DeformableObject(AssetBase):
     """
 
     def _initialize_impl(self):
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # obtain the first prim in the regex expression (all others are assumed to be a copy of this)
         template_prim = sim_utils.find_first_matching_prim(self.cfg.prim_path)
         if template_prim is None:
@@ -408,6 +408,4 @@ class DeformableObject(AssetBase):
         """Invalidates the scene elements."""
         # call parent
         super()._invalidate_initialize_callback(event)
-        # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._root_physx_view = None

source/isaaclab/isaaclab/assets/rigid_object/rigid_object.py

@@ -11,6 +11,7 @@ from typing import TYPE_CHECKING
 
 import omni.log
 import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -400,9 +401,8 @@ class RigidObject(AssetBase):
     """
 
     def _initialize_impl(self):
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # obtain the first prim in the regex expression (all others are assumed to be a copy of this)
         template_prim = sim_utils.find_first_matching_prim(self.cfg.prim_path)
         if template_prim is None:
@@ -501,5 +501,4 @@ class RigidObject(AssetBase):
         # call parent
         super()._invalidate_initialize_callback(event)
         # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._root_physx_view = None

source/isaaclab/isaaclab/assets/rigid_object_collection/rigid_object_collection.py

@@ -15,6 +15,7 @@ import omni.kit.app
 import omni.log
 import omni.physics.tensors.impl.api as physx
 import omni.timeline
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -529,9 +530,8 @@ class RigidObjectCollection(AssetBase):
     """
 
     def _initialize_impl(self):
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         root_prim_path_exprs = []
         for name, rigid_object_cfg in self.cfg.rigid_objects.items():
             # obtain the first prim in the regex expression (all others are assumed to be a copy of this)
@@ -687,5 +687,4 @@ class RigidObjectCollection(AssetBase):
         # call parent
         super()._invalidate_initialize_callback(event)
         # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._root_physx_view = None

source/isaaclab/isaaclab/sensors/contact_sensor/contact_sensor.py

@@ -14,6 +14,7 @@ from typing import TYPE_CHECKING
 
 import carb
 import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import PhysxSchema
 
 import isaaclab.sim as sim_utils
@@ -249,9 +250,8 @@ class ContactSensor(SensorBase):
 
     def _initialize_impl(self):
         super()._initialize_impl()
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # check that only rigid bodies are selected
         leaf_pattern = self.cfg.prim_path.rsplit("/", 1)[-1]
         template_prim_path = self._parent_prims[0].GetPath().pathString
@@ -418,6 +418,5 @@ class ContactSensor(SensorBase):
         # call parent
         super()._invalidate_initialize_callback(event)
         # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._body_physx_view = None
         self._contact_physx_view = None

source/isaaclab/isaaclab/sensors/frame_transformer/frame_transformer.py

@@ -11,7 +11,7 @@ from collections.abc import Sequence
 from typing import TYPE_CHECKING
 
 import omni.log
-import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -205,9 +205,8 @@ class FrameTransformer(SensorBase):
 
         body_names_regex = [tracked_prim_path.replace("env_0", "env_*") for tracked_prim_path in tracked_prim_paths]
 
-        # Create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # Create a prim view for all frames and initialize it
         # order of transforms coming out of view will be source frame followed by target frame(s)
         self._frame_physx_view = self._physics_sim_view.create_rigid_body_view(body_names_regex)
@@ -410,5 +409,4 @@ class FrameTransformer(SensorBase):
         # call parent
         super()._invalidate_initialize_callback(event)
         # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._frame_physx_view = None

source/isaaclab/isaaclab/sensors/imu/imu.py

@@ -10,7 +10,7 @@ from collections.abc import Sequence
 from typing import TYPE_CHECKING
 
 import isaacsim.core.utils.stage as stage_utils
-import omni.physics.tensors.impl.api as physx
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -123,9 +123,8 @@ class Imu(SensorBase):
         """
         # Initialize parent class
         super()._initialize_impl()
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # check if the prim at path is a rigid prim
         prim = sim_utils.find_first_matching_prim(self.cfg.prim_path)
         if prim is None:

source/isaaclab/isaaclab/sensors/ray_caster/ray_caster.py

@@ -15,6 +15,7 @@ import omni.log
 import omni.physics.tensors.impl.api as physx
 import warp as wp
 from isaacsim.core.prims import XFormPrim
+from isaacsim.core.simulation_manager import SimulationManager
 from pxr import UsdGeom, UsdPhysics
 
 import isaaclab.sim as sim_utils
@@ -118,9 +119,8 @@ class RayCaster(SensorBase):
 
     def _initialize_impl(self):
         super()._initialize_impl()
-        # create simulation view
-        self._physics_sim_view = physx.create_simulation_view(self._backend)
-        self._physics_sim_view.set_subspace_roots("/")
+        # obtain global simulation view
+        self._physics_sim_view = SimulationManager.get_physics_sim_view()
         # check if the prim at path is an articulated or rigid prim
         # we do this since for physics-based view classes we can access their data directly
         # otherwise we need to use the xform view class which is slower
@@ -287,5 +287,4 @@ class RayCaster(SensorBase):
         # call parent
         super()._invalidate_initialize_callback(event)
         # set all existing views to None to invalidate them
-        self._physics_sim_view = None
         self._view = None

source/isaaclab/isaaclab/sim/simulation_context.py

@@ -6,7 +6,6 @@
 import builtins
 import enum
 import numpy as np
-import sys
 import torch
 import traceback
 import weakref
@@ -261,17 +260,17 @@ class SimulationContext(_SimulationContext):
         #   you can reproduce the issue by commenting out this line and running the test `test_articulation.py`.
         self._gravity_tensor = torch.tensor(self.cfg.gravity, dtype=torch.float32, device=self.cfg.device)
 
-        # add callback to deal the simulation app when simulation is stopped.
-        # this is needed because physics views go invalid once we stop the simulation
+        # add a callback to keep rendering when a stop is triggered through different GUI commands like (save as)
         if not builtins.ISAAC_LAUNCHED_FROM_TERMINAL:
             timeline_event_stream = omni.timeline.get_timeline_interface().get_timeline_event_stream()
             self._app_control_on_stop_handle = timeline_event_stream.create_subscription_to_pop_by_type(
                 int(omni.timeline.TimelineEventType.STOP),
-                lambda *args, obj=weakref.proxy(self): obj._app_control_on_stop_callback(*args),
+                lambda *args, obj=weakref.proxy(self): obj._app_control_on_stop_handle_fn(*args),
                 order=15,
             )
         else:
             self._app_control_on_stop_handle = None
+        self._disable_app_control_on_stop_handle = False
 
         # flatten out the simulation dictionary
         sim_params = self.cfg.to_dict()
@@ -455,6 +454,7 @@ class SimulationContext(_SimulationContext):
     """
 
     def reset(self, soft: bool = False):
+        self._disable_app_control_on_stop_handle = True
         super().reset(soft=soft)
         # app.update() may be changing the cuda device in reset, so we force it back to our desired device here
         if "cuda" in self.device:
@@ -467,6 +467,7 @@ class SimulationContext(_SimulationContext):
         if not soft:
             for _ in range(2):
                 self.render()
+        self._disable_app_control_on_stop_handle = False
 
     def step(self, render: bool = True):
         """Steps the simulation.
@@ -662,7 +663,7 @@ class SimulationContext(_SimulationContext):
     Callbacks.
     """
 
-    def _app_control_on_stop_callback(self, event: carb.events.IEvent):
+    def _app_control_on_stop_handle_fn(self, event: carb.events.IEvent):
         """Callback to deal with the app when the simulation is stopped.
 
         Once the simulation is stopped, the physics handles go invalid. After that, it is not possible to
@@ -679,67 +680,10 @@ class SimulationContext(_SimulationContext):
             This callback is used only when running the simulation in a standalone python script. In an extension,
             it is expected that the user handles the extension shutdown.
         """
-        # check if the simulation is stopped
-        if event.type == int(omni.timeline.TimelineEventType.STOP):
-            # keep running the simulator when configured to not shutdown the app
-            if self._has_gui and sys.exc_info()[0] is None:
-                omni.log.warn(
-                    "Simulation is stopped. The app will keep running with physics disabled."
-                    " Press Ctrl+C or close the window to exit the app."
-                )
-                while self.app.is_running():
-                    self.render()
-
-        # Note: For the following code:
-        #   The method is an exact copy of the implementation in the `isaacsim.simulation_app.SimulationApp` class.
-        #   We need to remove this method once the SimulationApp class becomes a singleton.
-
-        # make sure that any replicator workflows finish rendering/writing
-        try:
-            import omni.replicator.core as rep
-
-            rep_status = rep.orchestrator.get_status()
-            if rep_status not in [rep.orchestrator.Status.STOPPED, rep.orchestrator.Status.STOPPING]:
-                rep.orchestrator.stop()
-            if rep_status != rep.orchestrator.Status.STOPPED:
-                rep.orchestrator.wait_until_complete()
-
-            # Disable capture on play to avoid replicator engaging on any new timeline events
-            rep.orchestrator.set_capture_on_play(False)
-        except Exception:
-            pass
-
-        # clear the instance and all callbacks
-        # note: clearing callbacks is important to prevent memory leaks
-        self.clear_all_callbacks()
-
-        # workaround for exit issues, clean the stage first:
-        if omni.usd.get_context().can_close_stage():
-            omni.usd.get_context().close_stage()
-
-        # print logging information
-        print("[INFO]: Simulation is stopped. Shutting down the app.")
-
-        # Cleanup any running tracy instances so data is not lost
-        try:
-            profiler_tracy = carb.profiler.acquire_profiler_interface(plugin_name="carb.profiler-tracy.plugin")
-            if profiler_tracy:
-                profiler_tracy.set_capture_mask(0)
-                profiler_tracy.end(0)
-                profiler_tracy.shutdown()
-        except RuntimeError:
-            # Tracy plugin was not loaded, so profiler never started - skip checks.
-            pass
-
-        # Disable logging before shutdown to keep the log clean
-        # Warnings at this point don't matter as the python process is about to be terminated
-        logging = carb.logging.acquire_logging()
-        logging.set_level_threshold(carb.logging.LEVEL_ERROR)
-
-        # App shutdown is disabled to prevent crashes on shutdown. Terminating carb is faster
-        self._app.shutdown()
-        self._framework.unload_all_plugins()
-        sys.exit(0)
+        if not self._disable_app_control_on_stop_handle:
+            while not omni.timeline.get_timeline_interface().is_playing():
+                self.render()
+        return
 
 
 @contextmanager

source/isaaclab/test/assets/test_articulation.py

@@ -613,7 +613,7 @@ class TestArticulation(unittest.TestCase):
                         # Play sim
                         sim.reset()
                         # Check if articulation is initialized
-                        self.assertFalse(articulation._is_initialized)
+                        self.assertFalse(articulation.is_initialized)
 
     def test_out_of_range_default_joint_vel(self):
         """Test that the default joint velocity from configuration is out of range."""
@@ -633,7 +633,7 @@ class TestArticulation(unittest.TestCase):
             # Play sim
             sim.reset()
             # Check if articulation is initialized
-            self.assertFalse(articulation._is_initialized)
+            self.assertFalse(articulation.is_initialized)
 
     def test_joint_pos_limits(self):
         """Test write_joint_position_limit_to_sim API and when default position falls outside of the new limits."""
@@ -649,7 +649,7 @@ class TestArticulation(unittest.TestCase):
                         # Play sim
                         sim.reset()
                         # Check if articulation is initialized
-                        self.assertTrue(articulation._is_initialized)
+                        self.assertTrue(articulation.is_initialized)
 
                         # Get current default joint pos
                         default_joint_pos = articulation._data.default_joint_pos.clone()