Be able to customize MAX_JOINTS and MAX_MORPH_WEIGHTS

[victorb]

What problem does this solve or what need does it fill?

Currently, MAX_JOINTS and MAX_MORPH_WEIGHTS are hard-coded to a pair of values that are described as "guaranteed to work everywhere" which I don't think it's true, since the max of those values depend on the GPU/platform.

These hard-coded limits puts both a maximum and minimum hardware requirement from the engine, with no developer choice if they want it to be higher/lower. For example, complex rigs easily blow past those limits, and really low specced hardware can't load things with those limits.

It makes sense that there are limits, but if they could be configurable, then developers don't need to fork bevyengine/bevy just because they want to support moderately complicated rigs. Developers should also be the ones who decide what hardware requirements they are OK with for their games, but right now Bevy is making that choice for them.

What solution would you like?

Some way of configuring MAX_JOINTS and MAX_MORPH_WEIGHTS without having to maintain a fork of Bevy.

What alternative(s) have you considered?

I did attempt a PR to just double the values, but it's not really a proper fix.

Beyond that, I think the only alternative is to add some heuristics to make Bevy automatically figure out those limits, but that sounds both error-prone, magical and still wouldn't give the developer themselves control over what their requirements are.

Additional context

• PR attempting to double the values: Double MAX_JOINTS and MAX_MORPH_WEIGHTS #15972
• Issue about adding more documentation about why the values are what they are: Document why MAX_JOINTS and MAX_MORPH_WEIGHTS are set #15974
• PR adding more docs: Document why MAX_JOINTS and MAX_MORPH_WEIGHTS are set #16324

cc @mockersf, @alice-i-cecile, @BenjaminBrienen as you seem to be the ones you've been involved with this previous