Vulkan: Disallow choosing the Occlusion Culling Buffer debug draw mode when occlusion culling is disabled in the Project Settings

[nonunknown]

Godot version

v4.0.dev.custom_build [cb4e421]

System information

manjaro Gnome 21, AMD R7 200 series, Intel i3 3.0 GHZ,8GB RAM

Issue description

When click at:

it doesnt show black&white scene which the user can see the occlusion culling buffer!

Steps to reproduce

N/a

Minimal reproduction project

N/a

[Calinou]

The occlusion culling buffer will only display if occlusion culling is enabled in the Project Settings. It's disabled by default since it has a cost, even when no occluders are present in the scene. (I think the ideal would be to enable occlusion culling as long as one OccluderInstance3D is detected in the scene tree, but doing this check in a large scene is likely too costly unless it's only done once in a "fire and forget" manner.)

If occlusion culling is disabled, I suggest graying out the option and adding a tooltip stating why it's disabled.

[nonunknown]

oh, I forgot to enable it, now its working!

[Calinou]

One issue with performing such a check is that you may have occlusion culling disabled in the project settings, but enabled on a SubViewport specifically. I'm not sure if it's still a good idea to gate access to the debug draw mode based on the project setting.

cc @clayjohn

Maybe allowing you to select the mode and display a text message on the viewport instead would be better.