Viewing Issue Advanced Details
ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
04593 Graphics Minor Always Jan 4, 2012, 19:25 Feb 6, 2019, 09:15
Tester hap View Status Public Platform
Assigned To Resolution Open OS
Status [?] Confirmed Driver aerofgt.cpp
Version 0.144u4 Fixed in Version Build
Fixed in Git Commit Github Pull Request #
Summary 04593: aerofgt: Sprites vs background alignment is sometimes off when scrolling.
Description Sprites vs background alignment is sometimes off when scrolling. This is especially noticeable when it's crowded on screen with the game having slowdowns.
Steps To Reproduce - just play
- easiest to reproduce bug with: Take the Japanese plane and power it up to the max, shoot a lot to make it taxing on the game and have it slow down. More chance for the bug to occur then, look at ground object sprites.
Additional Information driver says:
MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(400)) /* wrong but improves sprite-background synchronization */

Setting vblank time to anything else may improve or worsen the problem, but won't fix the problem completely. This is more likely a blatant hack than accurate emulation.
Github Commit
Regression Version
Affected Sets / Systems aerofgt
Attached Files
related to 05105Confirmed All games in fromance.c: Screen is shifted 
related to 04413Confirmed  tail2nos and clones: Title screen's car movement is inverted 
related to 00234Confirmed  sformula: Side-by-side test. 
User avatar
Senior Tester
Jan 4, 2012, 22:00
I do wonder if these games ever had proper sprite / bg sync on real hw.

If you look at the PSX version (Sonic Wings Special) it has horrific desync (at least in MAME/MESS), and afaik the PSX doesn't even have a concept of different layers...

Some evidence as to how bad the sync is (or if it remains perfect all the time) on real hardware would be interesting.
User avatar
Jan 5, 2012, 14:24
agreed, I'll set the bug to [possible]

btw, you have the ability/right to change bug status, for example setting this one to 'confirmed' if you know the bugreport is valid. It doesn't necessarily have to be an admin (like Tafoid) that does it.
User avatar
Dec 26, 2016, 00:22
VBlank is controlled by that funny CRTC device, also reinstating this being something to be done anyway.
User avatar
Senior Tester
Feb 5, 2019, 17:35
Here's a pcb video:
User avatar
Senior Tester
Feb 6, 2019, 09:15
edited on: Feb 6, 2019, 09:15
This is the type of thing where you'd need a 60fps video to really notice it, 30fps videos on YouTube are going to mask the issue even if it does occur on hardware.