Resolve BorderRect ambiguity

[ickshonpe]

Objective

In UI and world coordinates, “top” and “bottom” mean opposite things, so these fields are ambiguous. Anyone using BorderRect must decide themselves how to apply the vertical insets.

Fixes #21913

For more in detail motivation, see the replies to issue #21913

Solution

Replace the directional BorderRect fields (left, right, top, and bottom) with min_inset and max_inset Vec2 fields.

Using min_inset and max_inset removes the need to interpret top or bottom relative to the coordinate system, so the same logic will work consistently in both UI and 2D.

[kfc35]

Thank you for this!

[kfc35]

nit: for consistency with the other constructors, you can assign these insets to separate Vec2::new’s

[ickshonpe]

Not sure what you mean, this?

 pub const fn axes(horizontal: f32, vertical: f32) -> Self { Self { min_inset: Vec2::new(horizontal, vertical), max_inset: Vec2::new(horizontal, vertical), } }

I prefer the the single Vec2 constructor version I think as less error prone, though the difference is very marginal.

[ickshonpe]

I also considered swapping axes parameters to a Vec2. I think it might be more ergonomic, but a vector implies direction. The inputs here are directionless, so the semantics with separate f32's feel better to me.

[Hilpogar]

From what I understand, the min_inset is supposed to be the top_left corner in the UI coordinates and the bottom_left corner in the 2D World coordinate. But in the code, you consistently used the top_left corner as the min_inset for both the sprite and the UI. Is it an error or am I missing something ?