colors.h

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#pragma once
 
#include "base/angle.h"
#include "base/vec3.h"
 
// todo(Gustav): split into 2 headers, one color (rgb + linear) and one extra
 
namespace eu
{
 
struct Rgb
{
    float r;
    float g;
    float b;
 
    constexpr Rgb(float red, float green, float blue)
        : r(red)
        , g(green)
        , b(blue)
    {}
};
 
struct Lin_rgb
{
    float r; float g; float b;
};
 
struct OkHsv
{
    An hue;
    float saturation;
    float value;
};
 
struct OkHsl
{
    An hue;
    float saturation;
    float lightness;
};
 
struct Hsl
{
    An hue;
    float saturation;
    float lightness;
};
 
struct OkLch
{
    float l;
    float c;
    An h;
};
 
struct OkLab
{
    float l;
    float a;
    float b;
};
 
struct Color
{
    Rgb rgb;
    float alpha;
 
    constexpr Color(const Rgb& a_rgb, float a_alpha = 1.0f)
        : rgb(a_rgb)
        , alpha(a_alpha)
    {
    }
};
 
// linear-space gamma-space
// todo(Gustav): should the functions that take gamma still be used?
float linear_from_srgb(float value, float gamma);
Lin_rgb linear_from_srgb(const Rgb& value, float gamma);
 
float linear_from_srgb(float value);
Lin_rgb linear_from_srgb(const Rgb& value);
 
float srgb_from_linear(float value);
Rgb srgb_from_linear(const Lin_rgb& value);
 
 
// oklab & oklch
// from: https://bottosson.github.io/posts/oklab/
OkLab oklab_from_linear(const Lin_rgb& c);
Lin_rgb linear_from_oklab(const OkLab& c);
OkLch oklch_from_oklab(const OkLab& c);
OkLab oklab_from_oklch(const OkLch& c);
 
 
// gammut clipping functions from https://bottosson.github.io/posts/gamutclipping/
Lin_rgb gamut_clip_preserve_chroma(const Lin_rgb& rgb);
Lin_rgb gamut_clip_project_to_0_5(const Lin_rgb& rgb);
Lin_rgb gamut_clip_project_to_l_cusp(const Lin_rgb& rgb);
Lin_rgb gamut_clip_adaptive_L0_0_5(const Lin_rgb& rgb, float alpha = 0.05f);
Lin_rgb gamut_clip_adaptive_l0_l_cusp(const Lin_rgb& rgb, float alpha = 0.05f);
 
 
 
 
Rgb srgb_from_okhsv(const OkHsv& hsv);
OkHsv okhsv_from_srgb(const Rgb& rgb);
 
Rgb srgb_from_okhsl(const OkHsl& hsl);
OkHsl okhsl_from_srgb(const Rgb& rgb);
 
// srgb from hsl (not ok hsl)
Rgb srgb_from_hsl(const Hsl& hsl);
 
Lin_rgb keep_within(Lin_rgb c);
 
}
 
namespace eu::hues
{
// https://tympanus.net/codrops/css_reference/hsl/
constexpr eu::An red = An::from_degrees(0.0f);
constexpr eu::An orange = An::from_degrees(30.0f);
constexpr eu::An yellow = An::from_degrees(60.0f);
constexpr eu::An green = An::from_degrees(120.0f);
constexpr eu::An cyan = An::from_degrees(180.0f);
constexpr eu::An blue = An::from_degrees(240.0f);
constexpr eu::An magenta = An::from_degrees(300.0f);
}
 
namespace eu::colors
{
 
constexpr eu::Rgb rgb(int r, int g, int b)
{
    return {static_cast<float>(r) / 255.0f, static_cast<float>(g) / 255.0f, static_cast<float>(b) / 255.0f};
}
 
constexpr Hsl hsl(int deg, float s, float l)
{
    return {.hue = An::from_degrees(static_cast<float>(deg)), .saturation = s / 100.0f, .lightness = l / 100.0f};
}
 
constexpr auto white = eu::Rgb{1.0f, 1.0f, 1.0f};
constexpr auto black = eu::Rgb{0.0f, 0.0f, 0.0f};
 
// https://www.nature.com/articles/nmeth.1618
constexpr eu::Rgb orange = rgb(230, 159, 0);
constexpr eu::Rgb blue_sky = rgb(86, 180, 233);
constexpr eu::Rgb green_bluish = rgb(0, 158, 115);
constexpr eu::Rgb yellow = rgb(240, 228, 66);
constexpr eu::Rgb blue = rgb(0, 114, 178);
constexpr eu::Rgb red_vermillion = rgb(213, 94, 0);
constexpr eu::Rgb purple_redish = rgb(204, 121, 167);
 
}  //  namespace eu::colors