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2019-10-21 10:02

Proton

Registered: Jul 2019
Posts: 7

Ghost data on the right border while opening side borders

Hello Mates,

This is an oldschool coder having kinda issue.
Since I started coding again after nearby 30 years of break, I have faced this issue more than once.
Well, ages ago, we were not able to see everything clearly as we can see now using emulator or proper adjustable display whrere you can see the real borders.
For some unknown reason, some sprites may cause ghost data appearing in the right border. approx. 5 pixels or so.
This is not happening always, so why it happens?
Is it just another bug in the bug or what?

Bug can be seen here: http://loxa.pw/fig/ghostdatabug.png

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2019-10-22 22:13

tlr

Registered: Sep 2003
Posts: 1790

Quote: judging by the screenshot looks like the glitch happens on a specific xcoo, and iirc sprites glitch if they have xcoo changed while they are displayed.

From what I've been able to tell there is no effect when changing the x-pos of an already triggered sprite.

The theory is that the sprite shift register is loaded on the sprite data fetch and triggered when the x-pos matches, then shifts countinously (which eventually results in all zeroes) until the next fetch. Triggering again while triggered does nothing.

I'm happy to be proven wrong though.

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