CIRCLE(9.3) CIRCLE(9.3)
NAME
circle, disc, arc, ellipse, eldisc, elarc - circle drawing
functions for jerq
SYNOPSIS
#include <jerq.h>
void circle(bp, p, r, f) Bitmap *bp; Point p; int r; Code f;
void disc(bp, p, r, f) Bitmap *bp; Point p; int r; Code f;
void arc(bp, p0, p1, p2, f) Bitmap *bp; Point p0, p1, p2;
Code f;
void ellipse(bp, p, a, b, f) Bitmap *bp; Point p; int a, b;
Code f;
void eldisc(bp, p, a, b, f) Bitmap *bp; Point p; int a, b;
Code f;
void elarc(bp, p0, a, b, p1, p2, f) Bitmap *bp; Point p0,
p1, p2; int a, b; Code f;
DESCRIPTION
Circle draws the best approximate circle of radius r cen-
tered at point p in the Bitmap bp with Code f. The circle is
guaranteed to be symmetrical about the horizontal, vertical
and diagonal axes. Disc draws the corresponding disc.
Arc draws a circular arc centered on p0, travelling
counter-clockwise from p1 to the point on the circle closest
to p2.
Ellipse draws an ellipse centered at p with horizontal
semi-axis a and vertical semi-axis b in Bitmap bp with Code
f. Eldisc draws the corresponding elliptical disc. Elarc
draws the correspoding elliptical arc, travelling counter-
clockwise from the ellipse point closest to p1 to the point
closest to p2. (Beware the regrettable difference between
the calling conventions for arc and elarc.)
BUGS
When an endpoint of an arc lies on a tail of an ellipse so
thin that its ends degenerate into straight lines, elarc
does not try to distinguish which `side' of the tail the
point belongs on.