vg4->misc->angle_from_xy()

Return angle according to a given x-/y-direction.

SYNTAX

int vg4->misc->angle_from_xy(int xdelta, int ydelta, int *pixelpercent)

FUNCTION PARAMETERS

xdelta	x-direction in 1/100 pixels
ydelta	y-direction in 1/100 pixels
pixelpercent	Percent of pixels on which xdelta/ydelta is based, may be NULL

RETURN VALUE

Returns the angle in degrees from 0 to 359, or -1 if xdelta and ydelta are both 0

DESCRIPTION

Return angle according to a given x-/y-direction. The parameter pixelpercent, if not NULL, returns the velocity of the x-/y-direction.

EXAMPLE

int angle, xdelta, ydelta, pixelpercent;

/* x-direction shall be 0.87 pixels to the right */
xdelta = 87;
/* y-direction shall be 0.5 pixels upward */
ydelta = -50;

angle = vg4->misc->angle_from_xy(xdelta, ydelta, &pixelpercent);
/* now angle is 60, and pixelpercent is 100 which means based on 1 pixel */


/* x-direction shall be 1.74 pixels to the right */
xdelta = 174;
/* y-direction shall be 1 pixel upward */
ydelta = -100;

angle = vg4->misc->angle_from_xy(xdelta, ydelta, &pixelpercent);
/* now angle is 60, and pixelpercent is 200 which means based on 2 pixels */