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From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Problems with clipping
Message-ID: <12548@cbmvax.commodore.com>
Date: 11 Jun 90 19:48:04 GMT
References: <1959@cernvax.UUCP>
Reply-To: jesup@cbmvax (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 21

In article <1959@cernvax.UUCP> rmal@cernvax.UUCP (richard lucock) writes:
>routines.  For the first few 'zoom steps', I have no problems.  However, I
>find that when the vectors get very long (eg coordinates of +/-20000)
>funny things happen - the lines are draw outside the window area, wrap
>around the screen (off at the top, on again at the bottom) etc.
>
>I have checked that the coordinate *are* still within the range of the
>variable types required by the drawing routines.

	graphics and maybe layers have trouble dealing with positions
that are more 16 or 32K from 0,0.  The problem is that somethings are
manipulated in WORDs (such as pixel positions).

	Only solution at this point is to do your own clipping to
+-32K (or +-16K to be safer).  I advise using midpointing until it fits,
then hand it off to graphics.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"