From: Erik Thiele <erikyyy@studbox.uni-stuttgart.de>
  To  : ggi-develop@eskimo.com
  Date: Thu, 19 Aug 1999 19:10:29 +0200

Re: circle,dotted line

On Thu, Aug 19, 1999 at 06:23:50PM +0200, becka@rz.uni-duesseldorf.de wrote:
> > any urls to algorithms drawing shaped lines
> > and circles ?
> 
> Hmm - aren't they implemented in LibGGi2D ?

hmm. i browsed source code and found only interfaces
but no implementations.

i am c++ programmer do not understand black macro magic ;)

is there some code ???
or is libggi2d only a interface to not existing routines ?

> Dotted stuff is usually done like this
> 
> while(not done) {
> 
> 	rotl(mask);	/* rotate left. like mask=(mask<<1)+(mask>>31); */
> 	if (pattern&mask) really_draw();
> }
> 
> For circles there are several different algorithms. The most common one is 
> probably a squared bresenham variant, but that is pretty complex to
> understand. For simple stuff I'd resort to calculate a bunch of points
> on the border (like every 5 degrees or so) and draw lines in between.
thanks!

cu
erik


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