From 3653f24e060425831b8addbb6b450e0fd82729e4 Mon Sep 17 00:00:00 2001
From: Shadow Cat <shadowcatzero@protonmail.com>
Date: Sat, 20 Sep 2025 13:34:04 -0400
Subject: [PATCH] store color in linear

---
 src/layout/color.rs    | 24 ++++++++++++++++++++++--
 src/render/shader.wgsl | 19 +------------------
 src/testing/mod.rs     |  4 ++--
 3 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/src/layout/color.rs b/src/layout/color.rs
index 8b6e629..d058f5f 100644
--- a/src/layout/color.rs
+++ b/src/layout/color.rs
@@ -1,5 +1,6 @@
 #![allow(clippy::multiple_bound_locations)]
 
+/// stored in linear for sane manipulation
 #[repr(C)]
 #[derive(Clone, Copy, bytemuck::Zeroable, Debug)]
 pub struct Color<T: ColorNum> {
@@ -63,6 +64,7 @@ impl ColorNum for f32 {
 
 unsafe impl bytemuck::Pod for Color<u8> {}
 
+#[const_trait]
 pub trait F32Conversion {
     fn to(self) -> f32;
     fn from(x: f32) -> Self;
@@ -87,9 +89,27 @@ impl<T: ColorNum + F32Conversion> Color<T> {
             a: self.a,
         }
     }
+
+    pub fn srgb(r: T, g: T, b: T) -> Self {
+        Self {
+            r: s_to_l(r),
+            g: s_to_l(g),
+            b: s_to_l(b),
+            a: T::MAX,
+        }
+    }
 }
 
-impl F32Conversion for f32 {
+fn s_to_l<T: F32Conversion>(x: T) -> T {
+    let x = x.to();
+    T::from(if x <= 0.0405 {
+        x / 12.92
+    } else {
+        ((x + 0.055) / 1.055).powf(2.4)
+    })
+}
+
+impl const F32Conversion for f32 {
     fn to(self) -> f32 {
         self
     }
@@ -98,7 +118,7 @@ impl F32Conversion for f32 {
     }
 }
 
-impl F32Conversion for u8 {
+impl const F32Conversion for u8 {
     fn to(self) -> f32 {
         self as f32 / 255.0
     }
diff --git a/src/render/shader.wgsl b/src/render/shader.wgsl
index 9a3ae21..456390b 100644
--- a/src/render/shader.wgsl
+++ b/src/render/shader.wgsl
@@ -106,7 +106,7 @@ fn draw_texture(region: Region, info: TextureInfo) -> vec4<f32> {
 }
 
 fn draw_rounded_rect(region: Region, rect: Rect) -> vec4<f32> {
-    var color = read_color(rect.color);
+    var color = unpack4x8unorm(rect.color);
 
     let edge = 0.5;
 
@@ -133,20 +133,3 @@ fn distance_from_rect(pixel_pos: vec2<f32>, rect_center: vec2<f32>, rect_corner:
     return length(max(q, vec2(0.0))) - radius;
 }
 
-fn read_color(c: u32) -> vec4<f32> {
-    let color = unpack4x8unorm(c);
-    return vec4(
-        srgb_to_linear(color.r),
-        srgb_to_linear(color.g),
-        srgb_to_linear(color.b),
-        color.a,
-    );
-}
-
-fn srgb_to_linear(c: f32) -> f32 {
-    if c <= 0.04045 {
-        return c / 12.92;
-    } else {
-        return pow((c + 0.055) / 1.055, 2.4);
-    }
-}
diff --git a/src/testing/mod.rs b/src/testing/mod.rs
index 97dd9e9..c530b2b 100644
--- a/src/testing/mod.rs
+++ b/src/testing/mod.rs
@@ -157,10 +157,10 @@ impl Client {
             let rect = rect(color)
                 .id_on(Sense::click(), move |id, ctx: &mut Client, _| {
                     ctx.ui[main].inner.set_static(to);
-                    ctx.ui[id].color = color.add_rgb(-0.2);
+                    ctx.ui[id].color = color.mul_rgb(0.7);
                 })
                 .edit_on(Sense::HoverStart | Sense::unclick(), move |r, _| {
-                    r.color = color.add_rgb(0.4);
+                    r.color = color.add_rgb(0.2);
                 })
                 .edit_on(Sense::HoverEnd, move |r, _| {
                     r.color = color;