Parent / Child relationships with TileBundles. Chunking + a couple other questions

[miketwenty1]

I'm seeking help with some core ideas of bevy_ecs_tilemap.
I would like to spawn various things with my tile as I spawn them (i.e. tilebundle children). It seems all relationships of tiles and the things that could go in the tiles (i.e. animations, Text2d, etc..) are not actual children entities of the TileBundle's in the examples (please correct me if I'm wrong!). Whenever I try to spawn children of my tilebundles, it seems things never turn out the way I want, and I'm unsure if they are designed to be parent entities, or if I'm just simply doing something wrong.

I'm unable to take advantage of 2 general things because of this:

1. I'm not able to spawn things to a tile and given their relative position. (instead it seems everything is a global position).
2. I'm not able to easily take advantage of the "despawn recursive" ideas when I need to despawn tiles and all the things associated with them. For instance my text2d entities are still around with slightly more granular despawn logic than the TilemapBundle chunks that get all despawned at once.

A few other questions I have:

• Is this already a built in global x/y position for a tilebundle for bevy_ecs_tilemap? From what I've seen each TilemapBundle will have it's own x/y position for each TileBundle and there's no idea of a universe x/y coordinate when you are chunking and will have many TilemapBundle's at once. I was thinking it would be useful to have a component with the universe x/y position, but interested if this is ill advised.
• The state of each tile is important to me, what is a recommended way to store relevant data so I can correct textures/tiles/etc spawn? I was thinking a HashMap with the key being the global x/y position, but I'm wondering again if this is built into bevy_ecs_tilemap or if there's a recommended solution.
• What is the idea for old_position for TileBundles?

Thanks!!

[rparrett]

We've been discussing this a bit over in #582 recently. You might find the discussion there interesting.

I'm not able to spawn things to a tile and given their relative position. (instead it seems everything is a global position).

You can add Transform to your individual tiles when you spawn them, and all the transform propagation should work from Tilemap to the children of your tiles. You can use TilePos::center_in_world to get the correct value to put there. And it would be on you to maintain this transform if a tile is moved.

Visibility propagation from individual tiles to their children might not work as you expect though.

I'm not able to easily take advantage of the "despawn recursive" ideas when I need to despawn tiles and all the things associated with them.

You can totally make your tiles children of your Tilemap. This isn't something that's done automatically though, and there may be a performance impact.

What is the idea for old_position for TileBundles?

I think this is mostly for keeping track of moved tiles in the render chunks.

The state of each tile is important to me, what is a recommended way to store relevant data so I can correct textures/tiles/etc spawn?

I don't know if I totally understand the question, but components on a tile entity are a great way to store associated data. Or a HashMap<TilePos, Whatever>.

[miketwenty1]

@rparrett thank you for the quick response.

I added a Transform to my TileBundles, and the text is spawning properly with the correct parent!

If I try to specifically despawn TileBundle's themselves recursively the text (children) does indeed despawn.

I don't know if I totally understand the question, but components on a tile entity are a great way to store associated data

Let me try to reiterate. I care about the state of each tile, so i'll need to spawn the correct data in each tile as it comes up. If I'm despawning tiles, I don't believe the component idea will work for me.
I was wondering if there was a recommended or built in optimized tilestorage state mechanism in this crate. Otherwise I'll probably just use the HashMap idea to store the state of each tile and I suppose I'll need to set this as Resource and bring this in as a param for various systems that need it.