# Objective
The false and true arguments for the select statement in `lerp_hue_long`
are misordered, resulting in it taking the wrong hue path:
## Solution
Swap the arguments around.
Also fixed another case I found during testing. The hue was interpolated
even when it is undefined for one of the endpoints (for example in a
gradient from black to yellow). In those cases it shouldn't interpolate,
instead it should return the hue of the other end point.
## Testing
I added a `linear_gradient` module to the testbed `ui` example, run
with:
```
cargo run --example testbed_ui
```
In the linear gradients screen (press space to switch) it shows a column
of red to yellow linear gradients. The last gradient in the column uses
the OKLCH long path, which should look like this:
matching the same gradient in CSS:
https://jsfiddle.net/fevshkdy/14/
if the correct hue path is chosen.
# Objective
Add interpolation in HSL and HSV colour spaces for UI gradients.
## Solution
Added new variants to `InterpolationColorSpace`: `Hsl`, `HslLong`,
`Hsv`, and `HsvLong`, along with mix functions to the `gradients` shader
for each of them.
#### Limitations
* Didn't include increasing and decreasing path support, it's not
essential and can be done in a follow up if someone feels like it.
* The colour conversions should really be performed before the colours
are sent to the shader but it would need more changes and performance is
good enough for now.
## Testing
```cargo run --example gradients```
# Objective
- for smallvec some crates specify default features false, other dont.
turns out we dont need them
## Solution
- remove
## Testing
- 3d_scene
# Objective
- Progress towards #19887.
## Solution
- Convert `FromWorld` impls into systems that run in `RenderStartup`.
- Move `UiPipeline` init to `build_ui_render` instead of doing it
separately in `finish`.
Note: I am making several of these systems pub so that users could order
their systems relative to them. This is to match the fact that these
types previously were FromWorld so users could initialize them.
## Testing
- Ran `ui_material`, `ui_texture_slice`, `box_shadow`, and `gradients`
examples and it still worked.
# Objective
Move Bevy UI's rendering into a dedicated crate.
Motivations:
* Allow the UI renderer to be used with other UI frameworks than
`bevy_ui`.
* Allow for using alternative renderers like Vello with `bevy_ui`.
* It's difficult for rendering contributors to make changes and
improvements to the UI renderer as it requires in-depth knowledge of the
UI implementation.
## Solution
Move the `render` and `ui_material` modules from `bevy_ui` into a new
crate `bevy_ui_render`.
## Testing
Important examples to check are `testbed_ui`, `testbed_full_ui`,
`ui_material`, `viewport_node` and `gradients`.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
