Make the occlusion culling debug draw mode display a translucent overlay instead of replacing the viewport

[Calinou]

Describe the project you are working on

The Godot editor 🙂

Describe the problem or limitation you are having in your project

The debug draw mode for the new occlusion culling in master replaces the viewport, making it difficult to navigate a 3D world while it is active:

cc @JFonS

Describe the feature / enhancement and how it helps to overcome the problem or limitation

I suggest displaying a translucent colored overlay instead, like this (Color(1, 0, 0) at 50% opacity):

This would allow for easy, depth-aware navigation in the 3D editor while being able to view which meshes are occluders and which meshes aren't.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

This may not be trivial to implement as right now, the debug draw mode copies the occlusion culling buffer to the main framebuffer.

If this enhancement will not be used often, can it be worked around with a few lines of script?

No, as debug draw modes are handled by the renderer.

Is there a reason why this should be core and not an add-on in the asset library?

See above.