PhysicsScene.Simulate

Parameters

Returns

void Whether the simulation was run or not. Running the simulation during physics callbacks will always fail.

Description

Simulate physics associated with this PhysicsScene.

Calling this method causes the physics to be simulated over the specified step time. Only the physics associated with this PhysicsScene will be simulated. If this PhysicsScene is not the default physics Scene (see Physics.defaultPhysicsScene) then it is associated with a specific Scene and as such, only components added to that Scene are affected when running the simulation.

If you pass framerate-dependent step values (such as Time.deltaTime) to the physics engine, your simulation will be less deterministic because of the unpredictable fluctuations in framerate that can arise. To achieve more deterministic physics results, you should pass a fixed step value to PhysicsScene.Simulate every time you call it.

You can call PhysicsScene.Simulate in the Editor outside of play mode however caution is advised as this will cause the simulation to move GameObject that have a Rigidbody component attached. When simulating in the Editor outside of play mode, a full simulation occurs for all physics components including Rigidbody, Collider and Joint including the generation of contacts however contacts are not reported via the standard script callbacks. This is a safety measure to prevent allowing callbacks to delete objects in the Scene which would not be an undoable operation. Here is an example of a basic simulation that implements what's being done in the automatic simulation mode.

using UnityEngine;
using UnityEngine.SceneManagement;

public class MultiScenePhysics : MonoBehaviour
{
    private Scene extraScene;

    public void Start()
    {
        // First create an extra scene with local physics
        extraScene = SceneManager.CreateScene("Scene", new CreateSceneParameters(LocalPhysicsMode.Physics3D));

        // Mark the scene active, so that all the new GameObjects end up in the newly created scene
        SceneManager.SetActiveScene(extraScene);

        PopulateExtraSceneWithObjects();
    }

    public void FixedUpdate()
    {
        // All of the non-default physics scenes need to be simulated manually
        var physicsScene = extraScene.GetPhysicsScene();
        {
            var autoSimulation = Physics.autoSimulation;
            Physics.autoSimulation = false;
            physicsScene.Simulate(Time.fixedDeltaTime);
            Physics.autoSimulation = autoSimulation;
        }
    }

    public void PopulateExtraSceneWithObjects()
    {
        // Create GameObjects for physics simulation
        var sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
        sphere.AddComponent<Rigidbody>();
        sphere.transform.position = Vector3.up * 4;
    }
}

Additional resources: Physics.Simulate.