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diff --git a/README.md b/README.md new file mode 100644 index 0000000..a96a417 --- /dev/null +++ b/README.md @@ -0,0 +1,62 @@ +## An HLSL implementation of OKLAB + +OKLAB is a perceptually uniform color space. That means that blending +between colors in OKLAB space produces more perceptually uniform gradients, +without weird transitional colors or changes in perceptual brightness or +saturation. + + +*Top: HSV gradient varying only hue; Bottom: OKLCH gradient varying only hue.* + +The [original OKLAB blog post](https://bottosson.github.io/posts/oklab/) +explains its merits very well. + +OKLAB [should be supported in Unity +2022](https://twitter.com/bjornornorn/status/1512428218892095496?lang=en), but +for us stuck on older versions, a library like this is necessary. + +This is exploratory code and is *not* optimized. If using in a performance +critical setting, you should premultiply all matrices in your desired +transformation. + +APIs provided: +``` +float3 LRGBtoXYZ(float3 c); +float3 XYZtoLRGB(float3 c); + +float3 XYZtoOKLAB(float3 c); +float3 OKLABtoXYZ(float3 c); + +// Note: OKLCH hue is on the range [0, 2*PI], not [0, 1]. +float3 OKLABtoOKLCH(float3 c); +float3 OKLCHtoOKLAB(float3 c); + +// Everything below this line is unoptimized syntactic sugar. +float3 LRGBtoOKLAB(float3 c); +float3 OKLABtoLRGB(float3 c); + +float3 LRGBtoOKLCH(float3 c); +float3 OKLCHtoLRGB(float3 c); +``` + +The gradient above was generated with this fragment shader: +``` +fixed4 frag(v2f i) : SV_Target +{ + float4 albedo = 1; + + if (i.uv.y > 0.5) { + // HSV gradient + albedo.xyz = HSVtoRGB(float3(i.uv.x, 1.0, 1.0)); + } else { + // OKLAB gradient + float3 c0 = LRGBtoOKLCH(float3(1, 0, 0)); + c0.z += i.uv.x * 2 * 3.14159265; + albedo.xyz = OKLCHtoLRGB(c0); + } + + return albedo; +} +``` + +This content is released under the MIT license. |