Custom UI Render Pass

[NickTheFox99]

Hello, I believe I am pretty experienced in Bevy, but I have never touched more specific rendering aspects of Bevy. I am attempting to make a pixel-perfect "filter" for bevy by using 2 cameras to render to a small texture, then display that with "nearest" filter. I attempted to add UI by introducing a third camera, rendering second to the render texture, but it overwrites the texture black.

I've tried:

• Disabling the second camera to see if it's the problem (it is)
• Changing the ordering of cameras
• Setting the UICamera to RenderLayers::none()
• Adding a rectangle to the UICamera (it draws)

Why is this happening, and what can I possibly try to fix it?

Repo with code: https://github.com/NickTheFox99/bill-boards-bevy/tree/master
Relevant files in repo (in src): ui.rs, display.rs, player.rs

[NickTheFox99]

By chance, I looked at the pixel snapping example again. I tried adding Msaa::Off to the UICamera, and it fixed the issue.
Why did it work, though?