NAME¶
al_fixatan2 - Allegro 5 API
SYNOPSIS¶
-
#include <allegro5/allegro.h>
al_fixed al_fixatan2(al_fixed y, al_fixed x)
DESCRIPTION¶
This is a fixed point version of the libc atan2() routine. It computes the arc
tangent of y / x, but the signs of both arguments are used to
determine the quadrant of the result, and x is permitted to be zero. This
function is useful to convert Cartesian coordinates to polar coordinates.
Example:
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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());
RETURN VALUE¶
Returns the arc tangent of y / x in fixed point binary format
angle, from -128 to 128. If both x and y are zero, returns zero and sets
Allegro's errno to EDOM.