easeInOutSine16()

u16 fl::easeInOutSine16

(

u16

i

)

16-bit sine ease-in/ease-out function Takes an input value 0-65535 and returns an eased value 0-65535

Definition at line 327 of file ease.cpp.hpp.

                                        {
    // ease-in-out sine: -(cos(π*t) - 1) / 2
    // Handle boundary conditions explicitly
    if (i == 0)
        return 0;
    if (i == 65535)
        return 65535;
 
    // For 16-bit: use cos32 for efficiency and accuracy
    // Map i from [0,65535] to [0,8388608] in cos32 space (0 to half wave)
    // Formula: (1 - cos(π*t)) / 2 where t goes from 0 to 1
    // sin32/cos32 half cycle is 16777216/2 = 8388608
    u32 angle = ((fl::u64)i * 8388608ULL) / 65535ULL;
    i32 cos_result = fl::cos32(angle);
 
    // Convert cos32 output and apply easing formula: (1 - cos(π*t)) / 2
    // cos32 output range is [-2147418112, 2147418112]
    // We want: (2147418112 - cos_result) / 2, then scale to [0, 65535]
    fl::i64 adjusted = (2147418112LL - (fl::i64)cos_result) / 2;
    return (u16)((fl::u64)adjusted * 65535ULL / 2147418112ULL);
}

References cos32(), and FL_NO_EXCEPT.

Referenced by ease16(), ease16(), and easeInOutSine8().

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