PhysicsBody & PhysicsShape Trigger Grid

Hey, just thought I would post this in case it helps anyone else as I spent over 2 hours trying to figure out why one of my triggers wasn't firing (turned out you need a non Static PhysicsBody at least on one of the entities!)



These are the combinations of PhysicsBody.CollisionResponse and PhysicsShape.MotionType that trigger a Physics Trigger in DOTS/ECS.

This was created on

- Unity - 2020.1.11f1
- Unity Physics - Version 0.5.1-preview.2 - October 29, 2020
- Entities - Version 0.16.0-preview.21 - October 29, 2020

Code Used To Test:

Spoiler: Code

Code (CSharp):

1. public class PhysicsCollisionTest : SystemBase
2. {
3.     protected override void OnCreate()
4.     {
5.         _physicsWorld = World.GetOrCreateSystem<BuildPhysicsWorld>();
6.         _stepPhysicsWorld = World.GetOrCreateSystem<StepPhysicsWorld>();
7.         _ecbSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
8.     }
9.  
10.     protected override void OnUpdate()
11.     {
12.         // Debug.Log("PhysicsCollisionTest OnUpdate");
13.         // var ecb = _ecbSystem.CreateCommandBuffer().AsParallelWriter();
14.        
15.         Dependency = new TriggerJob
16.         {
17.             Version = 1,
18.             Name = GetComponentDataFromEntity<NameComponent>(),
19.             // Ecb = ecb,
20.         }.Schedule(_stepPhysicsWorld.Simulation, ref _physicsWorld.PhysicsWorld, Dependency);
21.        
22.         // _ecbSystem.AddJobHandleForProducer(Dependency);
23.     }
24.     private BuildPhysicsWorld _physicsWorld;
25.  
26.     private StepPhysicsWorld _stepPhysicsWorld;
27.     private EndSimulationEntityCommandBufferSystem _ecbSystem;
28.  
29. }
30.  
31. [BurstCompile]
32. public struct TriggerJob : ITriggerEventsJob
33. {
34.     public int Version;
35.  
36.     [ReadOnly] public ComponentDataFromEntity<NameComponent> Name;
37.  
38.     // public EntityCommandBuffer.ParallelWriter Ecb;
39.     public void Execute(TriggerEvent e)
40.     {
41.         var aName = Name[e.EntityA].Name;
42.         var bName = Name[e.EntityB].Name;
43.         Debug.Log($"Trigger Fires: EntityA[{aName}]={e.EntityA.Index} with EntityB[{bName}]={e.EntityB.Index} JobVersion={Version}");
44.     }
45. }

 

Found my issue of why a PhysicsBody was screwing my movement/location.
I have a fireball prefab, and inside there a sphere which initially had collider, physics shape. As I instantiate the prefab and move the prefab all was working, but when I added a PhysicsBody to the Sphere, I guess it controlled its own absolute "World Position" and no longer moved along with the prefab. So although I was moving the Prefab, the child sphere PhysicsBody was not moving! Wished there was a list of these gotchas,

@Havok/Unity do you know if there is anyway to contribute to the official Docs, things like this should be highlighted and documented, will save hours of learning/finding stuff out!