# Objective
Implements border radius for UI nodes. Adopted from #8973, but excludes
shadows.
## Solution
- Add a component `BorderRadius` which contains a radius value for each
corner of the UI node.
- Use a fragment shader to generate the rounded corners using a signed
distance function.
<img width="50%"
src="https://github.com/bevyengine/bevy/assets/26204416/16b2ba95-e274-4ce7-adb2-34cc41a776a5"></img>
## Changelog
- `BorderRadius`: New component that holds the border radius values.
- `NodeBundle` & `ButtonBundle`: Added a `border_radius: BorderRadius`
field.
- `extract_uinode_borders`: Stripped down, most of the work is done in
the shader now. Borders are no longer assembled from multiple rects,
instead the shader uses a signed distance function to draw the border.
- `UiVertex`: Added size, border and radius fields.
- `UiPipeline`: Added three vertex attributes to the vertex buffer
layout, to accept the UI node's size, border thickness and border
radius.
- Examples: Added rounded corners to the UI element in the `button`
example, and a `rounded_borders` example.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Zachary Harrold <zac@harrold.com.au>
Co-authored-by: Pablo Reinhardt <126117294+pablo-lua@users.noreply.github.com>
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