HELP RC_FILLEDCIRCLE                                David Young
                                                    April 1994

LIB * RC_FILLEDCIRCLE uses the RC_GRAPHIC facilities to draw a circular
blob filled with the current foreground colour.

rc_filledcircle(x, y, rad)
        The blob is drawn centred on (x, y) and with radius rad in the
        current *RC_GRAPHIC coordinates.

The algorithm exploits the eightfold symmetry of a circle on a square
grid to cut down computation, and uses a lookup table to hold the
outline coordinates for small circles. Its speed is therefore limited by
the primitive pixel-setting routine XpwDrawPoint, and it would be worth
implementing this facility at a lower level using the same algorithm.

The blob is always circular on the screen, even if rc_xscale and
rc_yscale differ.


--- $popvision/help/rc_filledcircle
--- Copyright University of Sussex 1994. All rights reserved.
