Fix rendering of sprites, text, and meshlets after #12582.

[pcwalton]

Sprite, Text, and Handle<MeshletMesh> were types of renderable entities that the new segregated visible entity system didn't handle, so they didn't appear.

Because bevy_text depends on bevy_sprite, and the visibility computation of text happens in the latter crate, I had to introduce a new marker component, SpriteSource. SpriteSource marks entities that aren't themselves sprites but become sprites during rendering. I added this component to Text2dBundle. Unfortunately, this is technically a breaking change, although I suspect it won't break anybody in practice except perhaps editors.

Fixes #12935.

Changelog

Changed

• Text2dBundle now includes a new marker component, SpriteSource. Bevy uses this internally to optimize visibility calculation.

Migration Guide

• Text now requires a SpriteSource marker component in order to appear. This component has been added to Text2dBundle.

[superdump]

Not a thorough review but looks ok. Nothing controversial in my opinion. Noting this in case others get to it more thoroughly before me.

[Elabajaba]

It fixes the bug for me.

It'd be nice if there was a way to collapse this into a 1 or 2 liner somehow, but not essential.

                check_visibility::<WithMeshletMesh>
                    .in_set(VisibilitySystems::CheckVisibility)
                    .after(VisibilitySystems::CalculateBounds)
                    .after(VisibilitySystems::UpdateOrthographicFrusta)
                    .after(VisibilitySystems::UpdatePerspectiveFrusta)
                    .after(VisibilitySystems::UpdateProjectionFrusta)
                    .after(VisibilitySystems::VisibilityPropagate)
                    .after(TransformSystem::TransformPropagate),

[Elabajaba]

I don't quite understand why we need this, but I also couldn't get this working with just Text so I assume it's necessary.

[pcwalton]

Hmm, actually I think I came up with a way to make that no longer necessary. I'll try it tonight.

[pcwalton]

Actually, never mind, it'd be uglier than the current solution.

The problem is that Text uses the sprite visibility checking system. But that system can't name Text as it's an upstream crate. So we need some marker component that the sprite visibility checker can name.

[pcwalton]

BTW, the idea I had was to introduce a "label" type that's different from the component type. That way Sprite and Text would have the same label. But then you'd need two check_visibility systems, one for each component, that together populate the same VisibleEntities list. I think that's uglier than just using SpriteSource.