[A83] Re: Screen refreshing when scrolling
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[A83] Re: Screen refreshing when scrolling
Try looking at the source code to Sqrxz.
Sqrxz loads the next tile in, calculates where the tile sprite is in ram,
adds y offset (get the correct row of the sprite), then checks a single
pixel from the sprite, based on X coordinate (ANDs the sprite with
%10000000>>x). If the pixel is true, then it sets the first bit at the
right edge of the graphscreen (turns on the pixel).
Of course, you can't use the code to sqrxz unless your data is formatted
identically to sqrxz...
(that was for horizonatl scrolling to the left)
>From: Darkfire139@aol.com
>Reply-To: assembly-83@lists.ticalc.org
>To: assembly-83@lists.ticalc.org
>Subject: [A83] Screen refreshing when scrolling
>
>I recently learned how to scroll the screen, but when it scrolls, I need
>the
>next part of the image that was off the screen to draw on the screen. (Onto
>the space generated by the screen being scrolled) The only way I thought I
>could accomplish this was by checking the number of times the screen has
>been
>scrolled, and drawing the specified column or row, based on that number.
>This
>doesn't sound right though. What do I do?
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