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gpui: Add linear gradient support to fill background (#20812)

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Release Notes:

- gpui: Add linear gradient support to fill background

Run example:

```
cargo run -p gpui --example gradient
cargo run -p gpui --example gradient --features macos-blade
```

## Demo

In GPUI (sRGB):

<img width="761" alt="image"
src="https://github.com/user-attachments/assets/568c02e8-3065-43c2-b5c2-5618d553dd6e">

In GPUI (Oklab):

<img width="761" alt="image"
src="https://github.com/user-attachments/assets/b008b0de-2705-4f99-831d-998ce48eed42">

In CSS (sRGB): 

https://codepen.io/huacnlee/pen/rNXgxBY

<img width="505" alt="image"
src="https://github.com/user-attachments/assets/239f4b65-24b3-4797-9491-a13eea420158">

In CSS (Oklab):

https://codepen.io/huacnlee/pen/wBwBKOp

<img width="658" alt="image"
src="https://github.com/user-attachments/assets/56fdd55f-d219-45de-922f-7227f535b210">


---

Currently only support 2 color stops with linear-gradient. I think this
is we first introduce the gradient feature in GPUI, and the
linear-gradient is most popular for use. So we can just add this first
and then to add more other supports.
This commit is contained in:
Jason Lee 2024-12-12 03:52:52 +08:00 • committed by GitHub
parent c594ccb0af
commit de89f8cf83
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GPG key ID: B5690EEEBB952194
9 changed files with 902 additions and 73 deletions
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235
crates/gpui/src/platform/blade/shaders.wgsl
View file

@ -15,18 +15,21 @@ struct Bounds {
origin: vec2<f32>,
size: vec2<f32>,
}
struct Corners {
top_left: f32,
top_right: f32,
bottom_right: f32,
bottom_left: f32,
}
struct Edges {
top: f32,
right: f32,
bottom: f32,
left: f32,
}
struct Hsla {
h: f32,
s: f32,
@ -34,6 +37,24 @@ struct Hsla {
a: f32,
}
struct LinearColorStop {
color: Hsla,
percentage: f32,
}
struct Background {
// 0u is Solid
// 1u is LinearGradient
tag: u32,
// 0u is sRGB linear color
// 1u is Oklab color
color_space: u32,
solid: Hsla,
angle: f32,
colors: array<LinearColorStop, 2>,
pad: u32,
}
struct AtlasTextureId {
index: u32,
kind: u32,
@ -43,6 +64,7 @@ struct AtlasBounds {
origin: vec2<i32>,
size: vec2<i32>,
}
struct AtlasTile {
texture_id: AtlasTextureId,
tile_id: u32,
@ -96,6 +118,24 @@ fn srgb_to_linear(srgb: vec3<f32>) -> vec3<f32> {
return select(higher, lower, cutoff);
}
fn linear_to_srgb(linear: vec3<f32>) -> vec3<f32> {
let cutoff = linear < vec3<f32>(0.0031308);
let higher = vec3<f32>(1.055) * pow(linear, vec3<f32>(1.0 / 2.4)) - vec3<f32>(0.055);
let lower = linear * vec3<f32>(12.92);
return select(higher, lower, cutoff);
}
/// Convert a linear color to sRGBA space.
fn linear_to_srgba(color: vec4<f32>) -> vec4<f32> {
return vec4<f32>(linear_to_srgb(color.rgb), color.a);
}
/// Convert a sRGBA color to linear space.
fn srgba_to_linear(color: vec4<f32>) -> vec4<f32> {
return vec4<f32>(srgb_to_linear(color.rgb), color.a);
}
/// Hsla to linear RGBA conversion.
fn hsla_to_rgba(hsla: Hsla) -> vec4<f32> {
let h = hsla.h * 6.0; // Now, it's an angle but scaled in [0, 6) range
let s = hsla.s;
@ -135,6 +175,43 @@ fn hsla_to_rgba(hsla: Hsla) -> vec4<f32> {
return vec4<f32>(linear, a);
}
/// Convert a linear sRGB to Oklab space.
/// Reference: https://bottosson.github.io/posts/oklab/#converting-from-linear-srgb-to-oklab
fn linear_srgb_to_oklab(color: vec4<f32>) -> vec4<f32> {
let l = 0.4122214708 * color.r + 0.5363325363 * color.g + 0.0514459929 * color.b;
let m = 0.2119034982 * color.r + 0.6806995451 * color.g + 0.1073969566 * color.b;
let s = 0.0883024619 * color.r + 0.2817188376 * color.g + 0.6299787005 * color.b;
let l_ = pow(l, 1.0 / 3.0);
let m_ = pow(m, 1.0 / 3.0);
let s_ = pow(s, 1.0 / 3.0);
return vec4<f32>(
0.2104542553 * l_ + 0.7936177850 * m_ - 0.0040720468 * s_,
1.9779984951 * l_ - 2.4285922050 * m_ + 0.4505937099 * s_,
0.0259040371 * l_ + 0.7827717662 * m_ - 0.8086757660 * s_,
color.a
);
}
/// Convert an Oklab color to linear sRGB space.
fn oklab_to_linear_srgb(color: vec4<f32>) -> vec4<f32> {
let l_ = color.r + 0.3963377774 * color.g + 0.2158037573 * color.b;
let m_ = color.r - 0.1055613458 * color.g - 0.0638541728 * color.b;
let s_ = color.r - 0.0894841775 * color.g - 1.2914855480 * color.b;
let l = l_ * l_ * l_;
let m = m_ * m_ * m_;
let s = s_ * s_ * s_;
return vec4<f32>(
4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s,
-1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s,
-0.0041960863 * l - 0.7034186147 * m + 1.7076147010 * s,
color.a
);
}
fn over(below: vec4<f32>, above: vec4<f32>) -> vec4<f32> {
let alpha = above.a + below.a * (1.0 - above.a);
let color = (above.rgb * above.a + below.rgb * below.a * (1.0 - above.a)) / alpha;
@ -197,6 +274,94 @@ fn blend_color(color: vec4<f32>, alpha_factor: f32) -> vec4<f32> {
return vec4<f32>(color.rgb * multiplier, alpha);
}
struct GradientColor {
solid: vec4<f32>,
color0: vec4<f32>,
color1: vec4<f32>,
}
fn prepare_gradient_color(tag: u32, color_space: u32,
solid: Hsla, colors: array<LinearColorStop, 2>) -> GradientColor {
var result = GradientColor();
if (tag == 0u) {
result.solid = hsla_to_rgba(solid);
} else if (tag == 1u) {
// The hsla_to_rgba is returns a linear sRGB color
result.color0 = hsla_to_rgba(colors[0].color);
result.color1 = hsla_to_rgba(colors[1].color);
// Prepare color space in vertex for avoid conversion
// in fragment shader for performance reasons
if (color_space == 0u) {
// sRGB
result.color0 = linear_to_srgba(result.color0);
result.color1 = linear_to_srgba(result.color1);
} else if (color_space == 1u) {
// Oklab
result.color0 = linear_srgb_to_oklab(result.color0);
result.color1 = linear_srgb_to_oklab(result.color1);
}
}
return result;
}
fn gradient_color(background: Background, position: vec2<f32>, bounds: Bounds,
sold_color: vec4<f32>, color0: vec4<f32>, color1: vec4<f32>) -> vec4<f32> {
var background_color = vec4<f32>(0.0);
switch (background.tag) {
default: {
return sold_color;
}
case 1u: {
// Linear gradient background.
// -90 degrees to match the CSS gradient angle.
let radians = (background.angle % 360.0 - 90.0) * M_PI_F / 180.0;
var direction = vec2<f32>(cos(radians), sin(radians));
let stop0_percentage = background.colors[0].percentage;
let stop1_percentage = background.colors[1].percentage;
// Expand the short side to be the same as the long side
if (bounds.size.x > bounds.size.y) {
direction.y *= bounds.size.y / bounds.size.x;
} else {
direction.x *= bounds.size.x / bounds.size.y;
}
// Get the t value for the linear gradient with the color stop percentages.
let half_size = bounds.size / 2.0;
let center = bounds.origin + half_size;
let center_to_point = position - center;
var t = dot(center_to_point, direction) / length(direction);
// Check the direct to determine the use x or y
if (abs(direction.x) > abs(direction.y)) {
t = (t + half_size.x) / bounds.size.x;
} else {
t = (t + half_size.y) / bounds.size.y;
}
// Adjust t based on the stop percentages
t = (t - stop0_percentage) / (stop1_percentage - stop0_percentage);
t = clamp(t, 0.0, 1.0);
switch (background.color_space) {
default: {
background_color = srgba_to_linear(mix(color0, color1, t));
}
case 1u: {
let oklab_color = mix(color0, color1, t);
background_color = oklab_to_linear_srgb(oklab_color);
}
}
}
}
return background_color;
}
// --- quads --- //
struct Quad {
@ -204,7 +369,7 @@ struct Quad {
pad: u32,
bounds: Bounds,
content_mask: Bounds,
background: Hsla,
background: Background,
border_color: Hsla,
corner_radii: Corners,
border_widths: Edges,
@ -213,11 +378,13 @@ var<storage, read> b_quads: array<Quad>;
struct QuadVarying {
@builtin(position) position: vec4<f32>,
@location(0) @interpolate(flat) background_color: vec4<f32>,
@location(1) @interpolate(flat) border_color: vec4<f32>,
@location(2) @interpolate(flat) quad_id: u32,
//TODO: use `clip_distance` once Naga supports it
@location(3) clip_distances: vec4<f32>,
@location(0) @interpolate(flat) border_color: vec4<f32>,
@location(1) @interpolate(flat) quad_id: u32,
// TODO: use `clip_distance` once Naga supports it
@location(2) clip_distances: vec4<f32>,
@location(3) @interpolate(flat) background_solid: vec4<f32>,
@location(4) @interpolate(flat) background_color0: vec4<f32>,
@location(5) @interpolate(flat) background_color1: vec4<f32>,
}
@vertex
@ -227,7 +394,16 @@ fn vs_quad(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) insta
var out = QuadVarying();
out.position = to_device_position(unit_vertex, quad.bounds);
out.background_color = hsla_to_rgba(quad.background);
let gradient = prepare_gradient_color(
quad.background.tag,
quad.background.color_space,
quad.background.solid,
quad.background.colors
);
out.background_solid = gradient.solid;
out.background_color0 = gradient.color0;
out.background_color1 = gradient.color1;
out.border_color = hsla_to_rgba(quad.border_color);
out.quad_id = instance_id;
out.clip_distances = distance_from_clip_rect(unit_vertex, quad.bounds, quad.content_mask);
@ -242,21 +418,23 @@ fn fs_quad(input: QuadVarying) -> @location(0) vec4<f32> {
}
let quad = b_quads[input.quad_id];
let half_size = quad.bounds.size / 2.0;
let center = quad.bounds.origin + half_size;
let center_to_point = input.position.xy - center;
let background_color = gradient_color(quad.background, input.position.xy, quad.bounds,
input.background_solid, input.background_color0, input.background_color1);
// Fast path when the quad is not rounded and doesn't have any border.
if (quad.corner_radii.top_left == 0.0 && quad.corner_radii.bottom_left == 0.0 &&
quad.corner_radii.top_right == 0.0 &&
quad.corner_radii.bottom_right == 0.0 && quad.border_widths.top == 0.0 &&
quad.border_widths.left == 0.0 && quad.border_widths.right == 0.0 &&
quad.border_widths.bottom == 0.0) {
return blend_color(input.background_color, 1.0);
return blend_color(background_color, 1.0);
}
let half_size = quad.bounds.size / 2.0;
let center = quad.bounds.origin + half_size;
let center_to_point = input.position.xy - center;
let corner_radius = pick_corner_radius(center_to_point, quad.corner_radii);
let rounded_edge_to_point = abs(center_to_point) - half_size + corner_radius;
let distance =
length(max(vec2<f32>(0.0), rounded_edge_to_point)) +
@ -277,13 +455,13 @@ fn fs_quad(input: QuadVarying) -> @location(0) vec4<f32> {
border_width = vertical_border;
}
var color = input.background_color;
var color = background_color;
if (border_width > 0.0) {
let inset_distance = distance + border_width;
// Blend the border on top of the background and then linearly interpolate
// between the two as we slide inside the background.
let blended_border = over(input.background_color, input.border_color);
color = mix(blended_border, input.background_color,
let blended_border = over(background_color, input.border_color);
color = mix(blended_border, background_color,
saturate(0.5 - inset_distance));
}
@ -408,7 +586,7 @@ fn fs_path_rasterization(input: PathRasterizationVarying) -> @location(0) f32 {
struct PathSprite {
bounds: Bounds,
color: Hsla,
color: Background,
tile: AtlasTile,
}
var<storage, read> b_path_sprites: array<PathSprite>;
@ -416,7 +594,10 @@ var<storage, read> b_path_sprites: array<PathSprite>;
struct PathVarying {
@builtin(position) position: vec4<f32>,
@location(0) tile_position: vec2<f32>,
@location(1) color: vec4<f32>,
@location(1) @interpolate(flat) instance_id: u32,
@location(2) @interpolate(flat) color_solid: vec4<f32>,
@location(3) @interpolate(flat) color0: vec4<f32>,
@location(4) @interpolate(flat) color1: vec4<f32>,
}
@vertex
@ -428,7 +609,17 @@ fn vs_path(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) insta
var out = PathVarying();
out.position = to_device_position(unit_vertex, sprite.bounds);
out.tile_position = to_tile_position(unit_vertex, sprite.tile);
out.color = hsla_to_rgba(sprite.color);
out.instance_id = instance_id;
let gradient = prepare_gradient_color(
sprite.color.tag,
sprite.color.color_space,
sprite.color.solid,
sprite.color.colors
);
out.color_solid = gradient.solid;
out.color0 = gradient.color0;
out.color1 = gradient.color1;
return out;
}
@ -436,7 +627,11 @@ fn vs_path(@builtin(vertex_index) vertex_id: u32, @builtin(instance_index) insta
fn fs_path(input: PathVarying) -> @location(0) vec4<f32> {
let sample = textureSample(t_sprite, s_sprite, input.tile_position).r;
let mask = 1.0 - abs(1.0 - sample % 2.0);
return blend_color(input.color, mask);
let sprite = b_path_sprites[input.instance_id];
let background = sprite.color;
let color = gradient_color(background, input.position.xy, sprite.bounds,
input.color_solid, input.color0, input.color1);
return blend_color(color, mask);
}
// --- underlines --- //