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# Objective Add support for interpolation in OKLab and OKLCH color spaces for UI gradients. ## Solution * New `InterpolationColorSpace` enum with `OkLab`, `OkLch`, `OkLchLong`, `Srgb` and `LinearRgb` variants. * Added a color space specialization to the gradients pipeline. * Added support for interpolation in OkLCH and OkLAB color spaces to the gradients shader. OKLCH interpolation supports both short and long hue paths. This is mostly based on the conversion functions from `bevy_color` except that interpolation in polar space uses radians. * Added `color_space` fields to each gradient type. ## Testing The `gradients` example has been updated to demonstrate the different color interpolation methods. Press space to cycle through the different options. --- ## Showcase 
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| UI Gradients |
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Support for UI node's that display a gradient that transitions smoothly between two or more colors.
To draw a UI node with a gradient insert the components BackgroundGradient and BorderGradient, which both newtype a vector of Gradients. If you set a background color, the background color is drawn first and the gradient(s) are drawn on top.
The are three gradient structs corresponding to the three types of gradients supported: LinearGradient, ConicGradient and RadialGradient. These are then wrapped by the Gradient enum discriminator which has Linear, Conic and Radial variants.
Each gradient type consists of the geometric properties for that gradient, a list of color stops and the color space used for interpolation. Color stops consist of a color, a position or angle and an optional hint. If no position is specified for a stop, it's evenly spaced between the previous and following stops. Color stop positions are absolute. With the list of stops:
vec![vec![ColorStop::new(RED, Val::Percent(90.), ColorStop::new(Color::GREEN, Val::Percent(10.))
the colors will be reordered and the gradient will transition from green at 10% to red at 90%.
Colors can be interpolated between the stops in OKLab, OKLCH, SRGB and linear RGB color spaces. The hint is a normalized value that can be used to shift the mid-point where the colors are mixed 50-50 between the stop with the hint and the following stop.
For sharp stops with no interpolated transition, place two stops at the same point.
ConicGradients and RadialGradients have a center which is set using the new UiPosition type. UiPosition consists of a normalized (relative to the UI node) Vec2 anchor point and a responsive x, y offset.