I think at least Nestopia does not trigger it at 9+ sprites (which I always lamented) if extra sprites are turned on, if you want something to test with.DRW wrote:But shouldn't the sprite overflow bit still be triggered at nine sprites, independent from how many sprites are actually capable to be shown on screen?
"City Trouble" by Den Kat Games
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Re: "City Trouble" by Den Kat Games
Download STREEMERZ for NES from fauxgame.com! — Some other stuff I've done: fo.aspekt.fi
Re: "City Trouble" by Den Kat Games
Thanks for that information.
And yes, this actually was the reason why the game freezes on some AVSes.
And yes, this actually was the reason why the game freezes on some AVSes.
My game "City Trouble":
Gameplay video: https://youtu.be/Eee0yurkIW4
Download (ROM, manual, artworks): http://www.denny-r-walter.de/city.html
Gameplay video: https://youtu.be/Eee0yurkIW4
Download (ROM, manual, artworks): http://www.denny-r-walter.de/city.html
Re: "City Trouble" by Den Kat Games
Weird that they would change the behavior of the flag when configured to display more sprites, since that could break existing logic.
IMO this should be a visual change only, specially when the sprite limit is eliminated, not increased. But even changing the behavior so the flag only gets set when the increased limit is broken doesn't really help.
IMO this should be a visual change only, specially when the sprite limit is eliminated, not increased. But even changing the behavior so the flag only gets set when the increased limit is broken doesn't really help.
Last edited by tokumaru on Mon Sep 18, 2017 9:08 am, edited 1 time in total.
Re: "City Trouble" by Den Kat Games
I imagine it would have been very tricky to have the OAM evaluator process both the normal OAM fetch pattern, which is required for increasing the sprite limit, and the pathological diagonal fetch pattern, which is required for accurate sprite overflow flag behavior. I guess the firmware could have treated "9th secondary OAM slot filled" as an approximation of the result of the pathological diagonal fetch pattern when the sprite limit is increased.
Re: "City Trouble" by Den Kat Games
Yeah, that's true. You can't easily "break" the evaluation process like the original PPU does and still fetch extra valid sprites.