Point light stops working when viewed from long distance

[jnhyatt]

Bevy version

0.16.1

Relevant system information

Reproduced on multiple GPUs

What you did

I put a point light and some geometry in the scene, then moved far away from it. Minimum repro: https://github.com/jnhyatt/bevy-lighting-bug (uses bevy_editor_cam for easy moving far away)

What went wrong

In the repro, zoom out away from the sphere and eventually the bright spot will disappear instantly. This is incorrect behavior because the light should always affect geometry near it regardless of the camera's position.

Additional information

I tried adjusting the light range to see if that had something to do with it, but to no effect. Tried a couple other random things. I don't really have any leads unfortunately.

[alice-i-cecile]

I bet this is due to the camera's far plane somehow. Does changing that modify this behavior?

[jnhyatt]

Ah yep, the light spot disappears at the far clipping plane, but the sphere stays visible. Notably that makes the documentation on PerspectiveProjection::far wrong:
Objects farther from the camera than this value will not be visible.
And this is a nice workaround but not really a fix I don't think? We use infinite reverse-Z right? So why would we cull lights without culling geometry?

[alice-i-cecile]

Yep, I still think this is a bug, but that investigation should help folks who are better at rendering than me figure out the right fix :)