Triggers
Trigger Volumes can be applied to a prim’s collision mesh and can be used to detect when another prim enters or leaves the trigger’s space.
Trigger Volumes
Crate a Trigger
Triggers are created by assigning a trigger Schema to a prim.
Note
The prim must have a collision mesh for the trigger to work
Setup the trigger using the PhysxTriggerAPI
USD schema.
from pxr import PhysicsSchemaTools, PhysxSchema, UsdPhysics
# optional, just in case the prim doesn't have a collision attribute already assigned
UsdPhysics.CollisionAPI.Apply(trigger_prim)
PhysxSchema.PhysxTriggerAPI.Apply(trigger_prim)
self.triggerStateAPI = PhysxSchema.PhysxTriggerStateAPI.Apply(trigger_prim)
Detect a Collision
Trigger Volumes don’t use python event callbacks, so instead we poll the trigger state per frame.
Note
Triggers can execute scripts on trigger “events”, see the Physics Demo Scene : Triggers for details
from pxr import PhysicsSchemaTools, PhysxSchema, UsdPhysics
def physics_update(self, e: carb.events.IEvent):
triggerColliders = self.triggerStateAPI.GetTriggeredCollisionsRel().GetTargets()
if len(triggerColliders) > 0:
for collision in triggerColliders:
print(f"Prim path: {collision} : is touching our Trigger")