Function solve_strict_subgamut

src/fl/gfx/rgbw_colorimetric.cpp.hpp:481–531

}

bool solve_strict_subgamut(const ProfileCache& cache, float s_r,
                           float s_g, float s_b,
                           float out_rgbw[4]) FL_NOEXCEPT {
    zero4(out_rgbw);

    const float value = max3f(s_r, s_g, s_b);
    if (value <= 1e-9f) {
        return true;
    }

    // Native topology authority is split by case:
    //   n == 1: exact single-axis identity is correct.
    //   n == 2: keep the active RG/RB/GB edge locked, but still solve that
    //           two-emitter topology colorimetrically from measured XYZ/Y.
    // The previous n<=2 passthrough fixed W/third-channel bleed, but regressed
    // dual edges into raw 1:1 input->output tuples.
    if (is_native_input_gamut(*cache.profile)) {
        const int n_active = count_active_channels(s_r, s_g, s_b);
        if (n_active == 1) {
            return native_single_identity(s_r, s_g, s_b, out_rgbw);
        }
        if (n_active == 2) {
            return solve_native_dual_edge_fixed_topology(cache, s_r, s_g,
                                                         s_b, out_rgbw);
        }
    }

    // Interior colors must preserve value separately from chroma. Solving the
    // already value-scaled node and then normalizing is what collapsed several
    // HSV v055/v075/v100 rows to identical saturated tuples. Instead, solve
    // the full-chroma endpoint once, normalize/project there, then apply the
    // original value scale.
    const float c_r = s_r / value;
    const float c_g = s_g / value;
    const float c_b = s_b / value;

    float X_full[3];
    source_rgb_to_XYZ(cache, c_r, c_g, c_b, X_full);

    float full[4];
    if (!solve_strict_subgamut_from_XYZ(cache, X_full, full)) {
        return false;
    }

    out_rgbw[0] = full[0] * value;
    out_rgbw[1] = full[1] * value;
    out_rgbw[2] = full[2] * value;
    out_rgbw[3] = full[3] * value;
    normalize4_if_needed(out_rgbw);
    return true;
}

bool solve_strict_subgamut_xy(const ProfileCache& cache,
                              const float xy_t[2], float Y_t,