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From: GRGREF@BYUVM.BITNET
Newsgroups: comp.sys.amiga.tech
Subject: Re: Writing clipping routines
Message-ID: <90210.094954GRGREF@BYUVM.BITNET>
Date: 29 Jul 90 15:49:54 GMT
References: <900721.220121.MDT.GRGREF@BYUVM> <32207@cup.portal.com>
Organization: Brigham Young University
Lines: 22

>I have the 1.3 release of the RKM Libraries & Devices, which explains in
>somewhat better detail what the Layers library does.  Basically, if what
>you need is _rectangular_ clipping, then the Layers library does it for you.
>You create a "Layer" (i.e. clipping rectangle) of the desired size, and
>then draw to its RastPort (NOT the window's RastPort).  The Layers library
>will clip to the RastPort.

What I need to know is not how to use the OS's clipping routines, but how to
*extend* them.  I need to add new routines which use the blitter directly,
but can clip using regular RastPorts.  I am quite experienced in graphics and
clipping, I just need to know how to use the Layers structures.

As an example, one routine I need to do is a replacement for the
BltMaskBitMapRastPort() routine.  This routine in the OS is very slow and
flashes the display terribly.  Therefore I want to create a replacement
routine which goes more quickly and smoothly.

Thanks!

>                Lee Willis

                                 Bryan Ford