Xref: utzoo comp.sys.amiga.tech:124 comp.sys.amiga:16830
Path: utzoo!mnetor!uunet!cbmvax!steveb
From: steveb@cbmvax.UUCP (Steve Beats)
Newsgroups: comp.sys.amiga.tech,comp.sys.amiga
Subject: Re: Multiple viewports
Message-ID: <3532@cbmvax.UUCP>
Date: 28 Mar 88 14:34:45 GMT
References: <2554@usceast.UUCP>
Reply-To: steveb@cbmvax.UUCP (Steve Beats)
Organization: Commodore Technology, West Chester, PA
Lines: 30
Keywords: two viewports for every bitmap

In article <2554@usceast.UUCP> baldwin@usceast.UUCP (Chuck Baldwin) writes:
>
>[Not being entirely sure where this should go, I post to both]
>
>I am trying to perform a conceptually simple task, of showing two
>different views of a large bitmap by using two ViewPorts.  My code
>is not in obvious error, and I get bizarre but repeatable results.
>
>Allocate a View, two ViewPorts, two RasInfos, one RastPort, and one BitMap
>Initialize these items appropriately:
>   Point both RasInfo to BitMap
>   Give each ViewPort it's own RasInfo
>   Link two ViewPorts through vp.Next field
>   Link ViewPorts into View
>Do arcane things to generate copper lists
>ON_DISPLAY;
>
>
>The problem is this ... the first ViewPort has graphics correctly
>rendered, but the second doesn't. In fact, the second ViewPort is black, which
>is not the currently defined background color.  It's as if the display 
>is not spewing electrons for the bottom half of the screen.
>
I suspect the line where you 'Do arcane things to generate copper lists'.  I
had a similar problem with linked ViewPorts.  When you call MakeVPort(v, vp)
it is not enough to call it with a pointer to the first ViewPort in your list.
YOU MUST CALL MakeVPort() FOR EVERY VIEWPORT LINKED TO vp.Next!!  I am pretty
sure this will fix your problems (poof).

	Steve