Fix render layers

[ChristopherBiscardi]

This is a rebased version of #49 which looks like it only needed merge conflicts resolved

[simbleau]

Hey Chris! Thanks for the assist. I'll take a look shortly.

[simbleau]

This almost works. I'll probably commit to this branch if that's ok with you, Chris. This is a good base.

[ChristopherBiscardi]

@simbleau totally cool with me!

[simbleau]

This is stickier than I thought. See #58 for additional discussion.

Nonetheless, I'm making progress.

[simbleau]

@ChristopherBiscardi

Render layers have been obeyed, there's a new render_layers example that uses Gizmos and render layers as well. Feel free to bend it to your will and let me know if behavior is as you expect.

In the example there are 2 cameras,

• Camera A renders with a camera order -1 and has a blue rect on Layer 2.
• Camera B has two vello animations with a camera order 1.
• Gizmos are rendered over everything else.

[ChristopherBiscardi]

awesome! thank you! I'll let you know how it goes.