Re: [stella] single line res

Subject: Re: [stella] single line res
From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 22 Jun 2000 16:57:20 +0200
At 18:56 21.06.2000 -0500, you wrote:

>I'm not sure I follow that.  The point is to be able to position the
>sprites at every scan line, when only updating the graphics register every
>other line.  This way if update graphics at the beginning of even lines,
>then you would turn on vdel if you wanted the graphics to start on the odd
>line.  Turn off vdell if you wan the graphics to start on the even one.

You are right. If you change the state of VDEL between frames, you can
get single scanline motion for the players. However you have to to update
the graphics for the different players on alternating scanlines, as that
is how the graphics data gets copied from the normal graphics register
into the delayed graphics register. There is no counter that transfers the
data automatically one scanline after you have written it to the normal
graphics register.

They don't explicitly say that this is how you have to do it, but it
is the method that is decribed in the programmers guide.

Ciao, Eckhard Stolberg

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