Function easeInOutCubic16

src/fl/math/ease.cpp.hpp:215–235

}

u16 easeInOutCubic16(u16 x) {
    const u32 MAX = 0xFFFF;             // 65535
    const u32 HALF = (MAX + 1) >> 1;    // 32768
    const fl::u64 M2 = (fl::u64)MAX * MAX; // 65535² = 4 294 836 225

    if (x < HALF) {
        // first half:  y = 4·(x/MAX)³  →  y_i = 4·x³ / MAX²
        fl::u64 xi = x;
        fl::u64 cube = xi * xi * xi; // x³
        // add M2/2 for rounding
        fl::u64 num = 4 * cube + (M2 >> 1);
        return (u16)(num / M2);
    } else {
        // second half: y = 1 − ((2·(1−x/MAX))³)/2
        // → y_i = MAX − (4·(MAX−x)³ / MAX²)
        fl::u64 d = MAX - x;
        fl::u64 cube = d * d * d; // (MAX−x)³
        fl::u64 num = 4 * cube + (M2 >> 1);
        return (u16)(MAX - (num / M2));
    }
}

u16 easeOutQuad16(u16 i) {
    // ease-out quadratic: 1 - (1-t)²