Filling drawings

[baltasarq]

There's no function or command "fill", allowing to pass two coordinates and making the computer to fill all delimited pixels with the current color.

Code:

circle 50, 50, 30
fill 50, 50

In the eighties, I used to fill a circle with a for loop:

Code:

circle 50, 50, 30
for i = 1 to 30
    circle 50, 50, i
next i

I suppose I could do something like this for rectangles, as well. This is, however, slow, ugly (certain pixels remain unplotted), and clumsy. Is there an alternate way?
Thanks,