VgaGames4

VgaGames4 - miscellaneous man-pages

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# 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 | For returning 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 */

SEE ALSO
vg4->misc->xy_from_angle()