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.


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--- _________Copyright __________University __of ______Sussex _____1994. ___All ______rights _________reserved.