How do you pause the physics simulation?

[Pyroglyph]

I'd like to be able to just pause the simulation both for using with a pause menu and for implementing mechanics like a dash ability that sends you shooting linearly in a single direction for a short time while removing control from the player (a la Celeste).
There doesn't seem to be any obvious way of doing this other than removing a core physics component (like TnuaRapier2dIOBundle), but that doesn't feel right to do. There has to be a better way, right?

[idanarye]

For the pause menu, you can use TnuaSystemSet. Bevy allows you to put conditions on existing system sets, so you can just put your own condition on it. This is how it is done in the demos:

bevy-tnua/examples/platformer_3d.rs

Line 40 in 3578071

app.configure_set(TnuaSystemSet.run_if(|tnua_active: Res<ExampleUiTnuaActive>| tnua_active.0));

Keep in mind that you also need to pause Rapier while in the pause menu.

As for removing controls from the player - I'm afraid it is not currently supported. I do want to implement things like dashes as part of Tnua (#6). For now, you don't have to remove the entire bundle - removing the TnuaMotor should be enough.

[Pyroglyph]

Thanks, that works great! I didn't know you could get resources in run_if, which is useful to know!

By the way, when I said "removing control from the player [while dashing]" I didn't mean "remove the TnuaPlatformerControls component", I meant "ignore player inputs" which was easy enough to achieve.

One more thing. I set up the condition to not run while dashing, and in the dash system I directly modify the Velocity component. It seems to work how I want it to (dash linearly for X time and then maintain velocity when physics is switched back on), but I'd like to know if there's some edge case that might break something. Is there a better way of doing it or is this fine?

[idanarye]

Thanks, that works great! I didn't know you could get resources in run_if, which is useful to know!

The function you pass to run_if is a Bevy system that returns a boolean. It can access anything a system does - components and resources alike.

but I'd like to know if there's some edge case that might break something. Is there a better way of doing it or is this fine?

Now that you mention it - yes. Tnua uses Rapier's ExternalForce to play with the gravity the character experiences. If you just disable the systems, and there was already something in that component, Tnua's apply_motors_system will not override it - and Rapier will keep applying that force. You may want to reset it manually.

[idanarye]

Starting from version 0.7:

1. The correct way to pause the simulation entirely is to set RapierConfiguration.physics_pipeline_active to false. Unlike previous versions,, starting from version 0.7 doing this will automatically pause the TnuaSystemSet systems, so no additional interference is required.
2. The correct way to temporarily disable Tnua for a specific entity is to add the TnuaToggle component to it. Change it to Disabled or SenseOnly when you need to control the rigid body without Tnua, and change it back to Enabled when you want Tnua to take over again.