Auto Cull 2d text

[miketwenty1]

I'm trying to cull 2d text so my game doesn't lag, I'm spawning a massive amount of 2d text in my game, and I want an easy way to hide it, if it's not insight of the camera.

Is there an easy way to do this without recreating the wheel? I see there is "ViewVisibility" https://docs.rs/bevy/latest/bevy/prelude/struct.ViewVisibility.html, but I'm unsure how to use it.

Any pointers or examples would be great!

[rparrett]

I suspect that adding an Aabb component to the text entity would be enough to make culling work.

[miketwenty1]

@rparrett Would you be able to provide an example of adding a lightweight phony Aabb component to an entity/2d text?

#[derive(Component)]
pub struct CullingAabbComponent(pub Aabb);


let phony = Aabb {
    center: Vec3A::new(0.0, 0.0, 0.0),
    half_extents: Vec3A::new(0.0, -0.0, 0.0),
};

...

builder.spawn((
  Text2dBundle {
      // ...
      ..default()
  },
  CullingAabbComponent(phony),
  ));
  ...     

I tried adding this component to my text2d bundle and it didn't seem to make a difference.

[rparrett]

Sure. Here's a quick and dirty adaptation of our many_sprites example, but with Text2d instead and a system to insert Aabb when the computed text layout info changes.

https://gist.github.com/rparrett/9cd3b145def1855f1baf87822e6a5f7a

[miketwenty1]

It's unclear to me what you're doing, on every loop you are inserting a new Aabb into Text2d entities?

In terms of what it should be doing.. is this different than what I'm attempting where I'm including Aabb when spawning the Text2dBundle. Are you able to confirm that your method actually works? Do you see anything wrong with my approach of including it as a component when spawning? I'm not seeing any changes.

[rparrett]

on every loop you are inserting a new Aabb into Text2d entitie

Only when TextLayoutInfo is updated.

Are you able to confirm that your method actually works

Yes, you can test this for yourself by removing the update_text_aabb from the app and observing the logged output as well as what should be an obvious degradation in frame rate.

Do you see anything wrong with my approach of including it as a component when spawning

Yes, the Bevy system that determines visibility based on Aabb is querying for an Aabb, so embedding the Aabb within your CullingAabbComponent won't work.

Adding the Aabb at spawn time will work fine, but I am adding it when TextLayoutInfo is updated so that I can give the Aabb correct dimensions.

[miketwenty1]

@rparrett this worked amazingly after just "insert"ing like you are doing after I spawn the text entity. Thanks for the help! my game no longer lags!