Sprite positions issue

Sprite positions issue
by oRBIT2002 on 2011-05-16 (#78239)

I've a small spriteproblem in my emulator. In some games, the positions have a slightly off Y-position (-1 pixel too much). However in other games it works fine which confuses me.
The titles I am testing are "The Goonies II (PAL)" (Great game btw) and "Super Mario Bros (PAL)".
The above have sprites positioned -1 pixel wrong. However "Super Mario Bros 3" (PAL) looks fine as default.
So if I fix one game I break the other, sort of.
Anyone happens to have any hints for me?

by Dwedit on 2011-05-16 (#78240)

Positions should be one pixel below what the Y coordinate byte says it should be. So a sprite at position 8.8 is actually at 8,9. No sprites are ever drawn in visible scanline 0.

by tokumaru on 2011-05-16 (#78250)

Also, some games (mostly early ones) use a "negative" Y scroll value to push the whole screen down 1 scanline, to compensate for the way sprites work. Maybe your emulator is not handling the Y scroll properly in those cases?

by 3gengames on 2011-05-16 (#78252)

^ My game does that right now to make it all align.