Needed: UIBlock-specific hierarchy event processing

[drew-512]

Hi Nova friends,

Our project here is looking good and we think it will be quite encouraging with Nova folks. One snag we're trying to work through and need help with...

There are two cameras:

• A stationary Overlay Camera for UIBlock screen overlays (e.g. media player UI and controls)
• A moving Overlay Camera controlled by Cinemachine -- we have a HUD UI system where UIBlock "panels" use physics to be spatially managed with automatic camera framing etc.

The issue is pointer and scroll event handling. First, we need to inject pointer and scroll updates to the floating layer UIBlock hierarchy via ScreenPointToRay() from the static camera. If there is no hit, then we would then inject it to the UIBlock hierarchies shown by the second camera, using ScreenPointToRay().

In short, there needs to be a way to inject screen ray-based events into specific UIBlock hierarchies.

Hoping there is a solution since many Unity apps have layered cameras, so this issue will only come up again for others. It would be huge to get a snippet we can run from inside the Nova namespace that will do the job (and we will maintain a patch here that makes private Nova props / methods internal as needed). My impression was that Nova is supposed to be a wholesale replacement of Canvas but this would be a notable exception.

I'm guessing the stock answer is to do a hit test on the first camera and then fallback to the second camera. Unfortunately, that is a non-starter since a hit from the first camera could be a coincidental hit from a UIBlock hierarchy aligned to the second camera. Also, we have other UIBlock hierarchies that reside in the background of both cameras.

Thanks!
Drew

[adgray1]

The layerMask parameter on Interaction.Point as well as the other Interaction methods (Raycast, SphereCollide, etc.) can be used to filter input updates to specific GameObject layers.

e.g.

1. Put all UIBlocks in the HUD UI hierarchy on a "HUD_UI" layer
2. Put all UIBlocks in the Overlay UI (e.g. media controls) hierarchy on an "Overlay_UI" layer
3. When you update input from the HUD UI camera, filter to the "HUD_UI" layer via layerMask
4. When you update input from the Overlay UI camera, filter to the "Overlay_UI" layer via layerMask

Please note layerMask is interpreted as a bitmask and not a layer index. More details here.

Is that along the lines of what you're looking for?

[drew-512]

Hi Adam, thanks for getting back.

Ok, this is welcome news, phew. So it looks like primary expense of this is that the all live UIBlock instances have to be traversed for each invocation of Interaction.RaycastAll() (while blocks not meeting the mask are stepped over for close to free). And since this traversal is done via Burst, it's pretty much a best-case scenario (other than you guys offering UIBlock hierarchy specific event handling described above).

Is that accurate or is the traversal more expensive. Files and lines numbers are welcome to better help me understand the costs. Trying to understand the dynamics when there are potentially thousands of live UIBlocks.

Thanks Adam!

[adgray1]

Yes, that's accurate :)

Going to mark this as "feature added" because there's already a way to filter input to specific hierarchies (via layers).