Implement First Pass Scene Assets

[zicklag]

This removes all the hard-coding for the scene spawning. Everything is loaded from assets.

I co-located the sprites for the fighters with the fighter YAML, but they could just as well be moved to a separate sprites folder if we wanted. It's setup so that when one asset references another asset the path is relative to the current file by default, but paths starting with a / are relative to the asset directory instead.

If we continue to put everything in assets, such as the UI theme images, etc. that are all referenced by a central .game.yaml, then the cool part is that the game becomes like a "punchy engine" where anybody can bring their own .game.yaml and totally change the feel and theme of the game.

This isn't implemented yet, but it's easy to do: you can even hook the web build of the game up so that you can use a query string to specify the asset URL to your own punchy game that you host on GitHub pages, making it a punchy game web player, and anybody can just host their assets on GitHub and then send people a link to play it with the punchy web player.

[odecay]

Started looking it over. Looks good so far.
Could you explain the metadata?

[odecay]

Okay looking really nice, On 2nd look I see what the metadata is.
Loading and spawning different entity types will be much simplified from what it was and the yaml files are nice and readable.

[erlend-sh]

the cool part is that the game becomes like a "punchy engine" where anybody can bring their own .game.yaml and totally change the feel and theme of the game.

That’s definitely the direction we wanna be going with. We also have plans to incorporate https://github.com/makspll/bevy_mod_scripting after Bevy v0.8

[zicklag]

We also have plans to incorporate https://github.com/makspll/bevy_mod_scripting after Bevy v0.8

What! Bevy gotten a scripting plugin while I'd been gone! Looks like the ecosystem's grown up quite a bit since half-way through the Bevy 0.5 era. :)

I'm going to have to look at that.

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I could see a case for not doing it this way because of rightward drift but it seems more straightforward.

Yeah, I'm fine either way. I've developed a habit of doing it like that to avoid rightward drift because I've ended up needing a lot of those in my own code before, but you're right that it's not really a problem here.

I asked about the pattern on the forum and they said eventually we should be able to shorten it to let Some(variable) = option else { return; }.

I'll push an update to apply all your suggestions.