74acb95ed3
# Objective Fixes #17561 ## Solution The anti-aliasing function used by the UI fragment shader is this: ```wgsl fn antialias(distance: f32) -> f32 { return saturate(0.5 - distance); // saturate clamps between 0 and 1 } ``` The returned value is multiplied with the alpha channel value to get the anti-aliasing effect. The `distance` is a signed distance value. A positive `distance` means we are outside the shape we're drawing and a negative `distance` means we are on the inside. So with `distance` at `0` (on the edge of the shape): ``` antialias(0) = saturate(0.5 - 0) = saturate(0.5) = 0.5 ``` but we want it to be `1` at this point, so the entire interior of the shape is given a solid colour, and then decrease as the signed distance increases. So in this PR we change it to: ```wgsl fn antialias(distance: f32) -> f32 { return saturate(1. - distance); } ``` Then: ``` antialias(-0.5) = saturate(1 - (-1)) = saturate(2) = 1 antialias(1) = saturate(1 - 0) = 1 antialias(0.5) = saturate(1 - 0.5) = 0.5 antialias(1) = saturate(1 - 1) = 0 ``` as desired. ## Testing ```cargo run --example button``` On main: <img width="400" alt="bleg" src="https://github.com/user-attachments/assets/314994cb-4529-479d-b179-18e5c25f75bc" /> With this PR: <img width="400" alt="bbwhite" src="https://github.com/user-attachments/assets/072f481d-8b67-4fae-9a5f-765090d1713f" /> Modified the `button` example to draw a white background to make the bleeding more obvious. |
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
Bevy UI
