From c498be6597f316c93ed6b9f0c13838802fb23123 Mon Sep 17 00:00:00 2001
From: Meghan Denny <hello@nektro.net>
Date: Thu, 14 Sep 2023 18:29:10 -0700
Subject: [PATCH] add LinearRgb

---
 LinearRgb.zig | 26 ++++++++++++++++++++++++++
 mod.zig       |  1 +
 sRGB.zig      | 18 ++++++++++++++++++
 3 files changed, 45 insertions(+)
 create mode 100644 LinearRgb.zig

diff --git a/LinearRgb.zig b/LinearRgb.zig
new file mode 100644
index 0000000000000000000000000000000000000000..07b9c9c806f96fddb3374a3ee0761ccfbf6faa2a
--- /dev/null
+++ b/LinearRgb.zig
@@ -0,0 +1,26 @@
+//! object representing a single color in the Linear RGB colorspace with channel values from 0-1
+
+const std = @import("std");
+const Self = @This();
+
+r: f32,
+g: f32,
+b: f32,
+a: f32,
+
+pub fn initRGBA(r: u8, g: u8, b: u8, a: u8) Self {
+    std.debug.assert(r >= 0.0 and r <= 1.0);
+    std.debug.assert(g >= 0.0 and g <= 1.0);
+    std.debug.assert(b >= 0.0 and b <= 1.0);
+    std.debug.assert(a >= 0.0 and a <= 1.0);
+    return Self{
+        .r = r,
+        .g = g,
+        .b = b,
+        .a = a,
+    };
+}
+
+pub fn eql(x: Self, y: Self) bool {
+    return x.r == y.r and x.g == y.g and x.b == y.b;
+}
diff --git a/mod.zig b/mod.zig
index 57ad889c6ce4d4b1c786cfc962819e770258c28b..3068e2b407e22eb6c28394df90b3f90ffba82e36 100644
--- a/mod.zig
+++ b/mod.zig
@@ -2,3 +2,4 @@ const std = @import("std");
 const color = @This();
 
 pub const sRGB = @import("./sRGB.zig");
+pub const LinearRgb = @import("./LinearRgb.zig");
diff --git a/sRGB.zig b/sRGB.zig
index f52c17efbc3fdce8532a34bea39ff6fecb62210d..d62e5c38e6ebd063d8a924b4e4d93244f3d08b35 100644
--- a/sRGB.zig
+++ b/sRGB.zig
@@ -2,6 +2,7 @@
 
 const std = @import("std");
 const Self = @This();
+const color = @import("./mod.zig");
 
 r: u8, // red value
 g: u8, // green value
@@ -63,3 +64,20 @@ pub fn format(x: Self, comptime fmt: []const u8, options: std.fmt.FormatOptions,
         std.fmt.fmtSliceHexLower(&.{x.b}),
     });
 }
+
+pub fn to_linear_rgb(x: Self) color.LinearRgb {
+    const lut = comptime blk: {
+        var res: [256]f32 = undefined;
+        for (0..256) |i| {
+            const c = @as(f32, @floatFromInt(i)) / 255.0;
+            res[i] = if (c <= 0.04045) c / 12.92 else std.math.pow(f32, (c + 0.055) / 1.055, 2.4);
+        }
+        break :blk res;
+    };
+    return color.LinearRgb.initRGBA(
+        lut[x.r],
+        lut[x.g],
+        lut[x.b],
+        lut[x.a],
+    );
+}
-- 
2.54.0