Added options for sorting transparent objects (port of PR #63040)

[BastiaanOlij]

This is a port of #63040 to Godot 4.

Bugsquad edit: This closes godotengine/godot-proposals#4099.

[BastiaanOlij]

One thing that needs to be discussed (was already talking about this with @clayjohn) in chat, is whether we should make the sort on the two Vulkan renderers apply the same logic the GLES (and Godot 3) renderer does when we're dealing with a perspective camera.

[clayjohn]

Looks good to me, As discussed on rocketchat, we should add this to decals and lights (which would supersede #60253). If you do so you will also need to update the GEOMETRY INSTANCE mask in instance_set_pivot_data()

[BastiaanOlij]

Looks good to me, As discussed on rocketchat, we should add this to decals and lights (which would supersede #60253). If you do so you will also need to update the GEOMETRY INSTANCE mask in instance_set_pivot_data()

I'm still not 100% sure about this so I'd like to move that into a separate PR if we wish to implement that. Lights and decals are applied to geometry in the shader as an additive process, I'm not sure if a sort is going to have any effect here?

[clayjohn]

Alright, lets go ahead and merge this and discuss sorting of other GeometryInstances after.

[akien-mga]

Thanks!

[Lippanon]

This 'sorting_offset' is only for when the material goes through the transparent pipeline, right? I was trying to use this to avoid z-fighting I was having and it didn't seem to work so I thought it was bugged, but I guess it doesn't work for opaque mats. The docs/mouse_over don't mention it at all, if that's the case.