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From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga.tech,comp.sys.amiga
Subject: Re: Multiple viewports
Keywords: two viewports for every bitmap
Message-ID: <5542@well.UUCP>
Date: 27 Mar 88 09:39:17 GMT
References: <2554@usceast.UUCP>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: "I don't like pink....."
Lines: 28

In article <2554@usceast.UUCP> baldwin@usceast.UUCP (Chuck Baldwin) writes:
>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.
>
	I'm assuming that you've got one viewport on top of another, sort of
like a dragged screen effect.

>[ Outlines his procedure... ]
>
>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.
>
	Sounds like it's not making it to the second ViewPort.  I would check
to make sure that the ViewPort.{DxOffset,DyOffset} variables are set up
correctly.  You must leave at least on blank video line between the bottom
of one viewport, and the top of the next one.

	It's hard to say what's going on without looking at the relevant
code section; this is only my suspicion.

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