al_fixatan2(3)

✨ al_fixatan2(3) ✨

okay bestie, welcome to the Allegro 5 API corner of the universe 💖 this little icon is al_fixatan2, and she's here to do trigonometry for you in fixed point. no floats, no drama, just vibes and angles 🎀

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🌸 SYNOPSIS 🌸

#include <allegro5/allegro.h>

al_fixed al_fixatan2(al_fixed y, al_fixed x)

like, that's it. two fixed point numbers in, one angle out. slay 💅

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🦋 DESCRIPTION 🦋

so bestie, this is literally the fixed point version of the libc atan2() routine. same energy, but without any of that floating point nonsense 💀

what she does: computes the arc tangent of y / x. but here's the iconic part — the signs of both arguments get used to determine the quadrant of the result, and x is permitted to be zero. so she's not just blindly dividing, she's actually paying attention to where you are on the plane 👑 iykyk

this function is useful to convert Cartesian coordinates to polar coordinates. literally her whole purpose in life ✨

🍓 Example 🍓

al_fixed result;

/* Sets `result' to binary angle 64. */
result = al_fixatan2(al_itofix(1), 0);

/* Sets `result' to binary angle -109. */
result = al_fixatan2(al_itofix(-1), al_itofix(-2));

/* Fails the assert. */
result = al_fixatan2(0, 0);
assert(!al_get_errno());

look at her go 😭 note that last one — when both are zero she sets errno and the assert fails, which is the whole point of the example. read it carefully bestie, don't come for me 🫶

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🌈 RETURN VALUE 🌈

returns the arc tangent of y / x in fixed point binary format angle, from -128 to 128. that range is not a suggestion, it's the whole map 🗺️

but if both x and y are zero? returns zero and sets Allegro's errno to EDOM. that's the error case, no cap 💀

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⚠️ heads up gorgeous — the (0, 0) case is the one that gives you EDOM, so if you're checking for it, al_get_errno() after the call is your bestie 🎀

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and that's the tea 💜 this page came from the Allegro reference manual, manual name al_fixatan2(3) — big fan honestly — and the version/date on the tin is the Allegro reference manual, al_fixatan2(3). mwah, go write some polar coordinates, queen 👑🌸