Path: utzoo!mnetor!uunet!husc6!uwvax!puff!avery
From: avery@puff.cs.wisc.edu (Aaron Avery)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Multiple ViewPorts
Message-ID: <1627@puff.cs.wisc.edu>
Date: 29 Apr 88 12:03:35 GMT
References: <8804251835.AA01654@jade.berkeley.edu>
Reply-To: avery@puff.WISC.EDU (Aaron Avery)
Organization: U of Wisconsin CS Dept
Lines: 24

In article <8804251835.AA01654@jade.berkeley.edu> BBOURBIN@UMDD.BITNET (Brett S Bourbin) writes:
>I am trying to write a program which uses multiple viewports so that I can
>have a double buffered upper screen, which is 352 X 130 lines (overscanned)
>and a bottom section which is 288 by 108 lines (narrow screen).  I am setting
>the DxOffset and DyOffsets to -16 and -16 for the top and 16 and 110 for the
>bottom section.  The routine I wrote is not working.  Matter of fact, it will
>not even execute my second ViewPort initialization code.  Could any please
>send me a code fragment which sets up two viewports to use different color
>palettes and different size screens?

If you examine those DyOffsets carefully, you'll find that 130 (from the
height of the upper screen) plus -16 (it's DyOffset) is more than 110 (from
the DyOffset for the bottom screen). That is -- 130 + (-16) = 114, and
114 > 110. I think you're trying to open overlapping ViewPorts, which the
system will not let you do. One additional note: you must allow at least
one scan line between the two ViewPorts, so that the copper can stuff the
new bitplane pointers, color registers, and screen dimention info into the
appropriate registers. I hope that's your only problem, as you SHOULD be able
to do what you're trying to do quite easily, especially since you seem to be
able to open the top screen already!

-- 
Aaron Avery (avery@puff.cs.wisc.edu)
	    ({seismo,caip,allegra,harvard,rutgers,ihnp4}!uwvax!puff!avery)