tone_map.hpp

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#pragma once

 
#include <array>
#include <cstdint>
#include <string_view>
 
namespace orrery::viz {

struct ToneMapping {
    float exposure = 1;

    float white_point = 4;
};

[[nodiscard]] float tone_curve(float radiance, ToneMapping mapping) noexcept;

[[nodiscard]] std::uint8_t encode_srgb(float linear) noexcept;

[[nodiscard]] std::array<std::uint8_t, 3> to_display(float red, float green, float blue,
                                                     ToneMapping mapping) noexcept;

[[nodiscard]] constexpr std::string_view tone_curve_glsl() noexcept {
    return R"(vec3 orrery_tone_curve(vec3 radiance, float exposure, float white_point) {
    vec3 exposed = max(radiance * exposure, vec3(0.0));
    vec3 mapped = exposed * (1.0 + exposed / (white_point * white_point)) / (1.0 + exposed);
    return clamp(mapped, 0.0, 1.0);
}
)";
}
 
} // namespace orrery::viz