Resolved How to hide entity from simulation, and then unhide it

Resolved

Physics-only exclude:

Universal exclude:

Original post

Hi, I've got a cube that I want to smash into pieces. I've got the pieces, too, but I want to hide them from the simulation until the cube should be smashed.

What's the recommended way to hide an entity from the simulation until it's ready to be simulated?

Idea 1: Collision Filter

Set "Collides with" of the "Collision Filter" of each piece to "Nothing" (and set gravity to zero). Then set it to "Everything" (for example) when the simulator should process them (and set gravity to default).

Counter-thought: Maybe this would add waste to the broadphase of the physics simulation, by making it check for overlaps between the pieces and other bodies despite the pieces not being ready yet.

Counter-counter thought: Maybe the simulator completely ignores those with the "Nothing" setting under their "Collides with" field.

Idea 2: PhysicsCollider

Add "PhysicsCollider", "PhysicsVelocity", and so on to each piece when the simulator should process them.

Counter-thought 1: Have to do it from code instead of using the nice PhysicsBody GameObject authoring component.

Counter-thought 2: Maybe it's expensive to do all those structural changes.

Idea 3: Second world

Create some sorta second sleepy physics world, from which one can pull physics entities into the main world to be simulated.

Idea 4: Subscene

Load a subscene that has all the pieces ready with PhysicsColliders and everything.

Thanks for any replies!

 

EDIT: Correction: HybridRenderer 0.11 supports lightmaps.

Original reply

The Subscene idea seemed great but doesn't seem to work without the HybridRenderer. I'm using Mesh Filter + Mesh Renderer instead of the HybridRenderer because the latter doesn't support lightmaps yet.

I could try to re-establish the connection between each entity with each GameObject. I was using Convert-and-Inject to establish the connection but this goes away with subscenes.

 

On the Physics side you can add a

PhysicsExclude

component to any Entity you don't want included in the simulation.

 

Also in the Material you have CollisionResponse, you can set it to None and change it when the time comes. But Steve's suggestion is definitely more efficient as it skips more steps.

 

The Disabled component excludes an entity from all systems, by excluding them from all EntityQueries.

EntityManager.SetEnabled(entity, false) adds the Disabled component.

This could be overkill for some use cases but I thought I'd mention it here.