0.15 (sort of)

[richchurcher]

So this is what happens when you blithely decide that, since you're gonna need bevy_ecs_tilemap again soon, you may as well try to upgrade it for 0.15. Uh, yeah. Some of the rendering stuff is well over my head! 😅

This is not a working update, but I'm leaving it here in case you can cherry pick some of the simpler commits to save you some time. I'll keep trying in the meantime, I'm learning quite a bit from it... but please don't feel the need to spend any significant time reviewing it.

It does include fixes for the following:

• Remove Component trait impl from Handle<T> bevyengine/bevy#15716 Handle<M> wrapper
• Pack multiple vertex and index arrays together into growable buffers. bevyengine/bevy#14257 GpuMesh -> RenderMesh but the implementation is nowhere near done, there's quite a lot to unpack there that I don't grok yet
• aligning public apis of Time,Timer and Stopwatch bevyengine/bevy#15962 elapsed_seconds -> elapsed_secs
• Deprecate get_or_spawn bevyengine/bevy#15652 get_or_spawn deprecation
• Refactor AsBindGroup to use a associated SystemParam. bevyengine/bevy#14909 as_bind_group args, needed charlotte's help with that one!
• a required components migration. I'm by no means completely convinced by the naming scheme, and would welcome alternatives. But in the end it seemed to make sense to:
  • rename MaterialTilemap to TilemapMaterial...
  • ...in order to create MaterialTilemap to replace MaterialTilemapBundle

[ChristopherBiscardi]

thanks! your effort is much appreciated!

[richchurcher]

I am being very slow, but hopefully I can get it to the point where someone who knows about rendering can take over!

[richchurcher]

OK. I think that's all the low-hanging fruit. Now, how the hell do I get all this rendering working 🤔

[richchurcher]

@ChristopherBiscardi can I ask: does the rendering code need a bit of a re-think? Given the retained render world changes (Entity/MainEntity), the GpuMesh/RenderMesh changes (MeshAllocator etc).

The deeper I dig, the more I wonder if it needs an experienced hand to say, "yep, we still need this bit", or "no, all this can be simplified". I can keep plugging away at it, just wanted to check in first to be sure I'm actually spending time on the right things. For example, as @tychedelia points out,

TileMapId wraps an entity that is actually MainEntity in the render world

and I haven't really got the first idea how to solve that 🤔 General guidance and suggestions very welcome.

[richchurcher]

In the meantime, I'm going to start by working my way through the Extract part of the pipeline, since that seems likely to be affected by retained rendering world.

Edit: I note this code makes use of .insert_or_spawn_batch which seems like it might be deprecated.

[ChristopherBiscardi]

There will be some changes for the retained rendering world but I'd like to avoid large sweeping changes otherwise, at least for the migration to 0.15-compatible. We can revisit the implementation in a larger way after getting a 0.15-compatible version out. For example, things like taking advantage of Required Components would be a breaking change that I'd like to leave for after the 0.15-compatible release if possible to make it easier for users of the crate to upgrade Bevy.

Re: the .insert_or_spawn_batch you've linked an issue that wants to deprecate it but not an actual deprecation so while we can think about removing the usage its not something that should be the top priority until it actually is deprecated or removed (it doesn't look slated for 0.15 and it also is labelled contentious).

I'll have more time to spend on this later this week. I likely won't get to much this weekend.

[richchurcher]

Hrm, I could also take a peek at the minimum possible changeset, sans required components... but I think there are still gonna be rendering issues. I'll investigate.

[evilenzo]

Sorry, I'm not good at rendering at all but I also want to help you a little. Just made a little pr to @richchurcher fixing remaining issues in examples: richchurcher#2

[richchurcher]

Yeah, I've definitely arrived at my limit with the rendering stuff, it needs a more experienced hand! Once I see a few examples, I think I'll be able to approach it with more confidence.

Please feel free to close this or cherry-pick whatever you find useful.

[rparrett]

Here's one possibility for migrating bevyengine/bevy#14257: rparrett@2f66d8f

@ChristopherBiscardi does that seem like a reasonable strategy?

edit: that branch is now migrated chronologically up to just before the retained render world commit.
edit: it probably makes sense to skip ahead to 15756 if continuing from where I left off. I attempted the retained render world migration and I think I'm running into some sort of bug that would be clarified by that followup PR.