[Home](./index.md) > [server](./server.md) > [Simulation](./server.simulation.md) ## Simulation class Represents the physics simulation for a world. When to use: advanced physics queries, custom gravity, or debug rendering. Do NOT use for: typical movement; use entity/rigid body APIs instead. **Signature:** ```typescript export default class Simulation extends EventRouter ``` **Extends:** [EventRouter](./server.eventrouter.md) ## Remarks Access via `World.simulation`. The simulation drives all collision and contact events for blocks and entities.

Events

This class is an EventRouter, and instances of it emit events with payloads listed under `SimulationEventPayloads`. \*\*Category:\*\* Physics The constructor for this class is marked as internal. Third-party code should not call the constructor directly or create subclasses that extend the `Simulation` class. ## Properties
Property Modifiers Type Description
[gravity](./server.simulation.gravity.md) `readonly` RAPIER.Vector3 The gravity vector for the simulation. \*\*Category:\*\* Physics
[isDebugRaycastingEnabled](./server.simulation.isdebugraycastingenabled.md) `readonly` boolean Whether debug raycasting is enabled. \*\*Category:\*\* Physics
[isDebugRenderingEnabled](./server.simulation.isdebugrenderingenabled.md) `readonly` boolean Whether debug rendering is enabled. \*\*Category:\*\* Physics
[timestepS](./server.simulation.timesteps.md) `readonly` number The fixed timestep for the simulation. \*\*Category:\*\* Physics
[world](./server.simulation.world.md) `readonly` [World](./server.world.md) The world this simulation belongs to. \*\*Category:\*\* Physics
## Methods
Method Modifiers Description
[enableDebugRaycasting(enabled)](./server.simulation.enabledebugraycasting.md) Enables or disables debug raycasting for the simulation.
[enableDebugRendering(enabled, filterFlags)](./server.simulation.enabledebugrendering.md) Enables or disables debug rendering for the simulation.
[getContactManifolds(colliderHandleA, colliderHandleB)](./server.simulation.getcontactmanifolds.md) Gets the contact manifolds for a pair of colliders.
[intersectionsWithRawShape(rawShape, position, rotation, options)](./server.simulation.intersectionswithrawshape.md) Gets the intersections with a raw shape.
[raycast(origin, direction, length, options)](./server.simulation.raycast.md) Casts a ray through the simulation and returns the first hit.
[setGravity(gravity)](./server.simulation.setgravity.md) Sets the gravity vector for the simulation.