Active sprites rendered one pixel to the right of actual location

(Up to Tricks and glitches (first generation))

The glitch occurring at the half-pixel level (or "Hires" mode) in WinUAE 4.0.0.

In WinUAE, the sprites for worms, projectiles, mines and in-motion gravestones can be shifted to the right by one pixel, resulting in an inaccurate representation of the object's current location. Once the object has stopped moving or is no longer active, the sprite shifts back to its "real" location. This issue is still present as of WinUAE 4.0.0.

An extreme version of this glitch is also present in FS-UAE, a multi-platform Amiga emulator - the entire horizontal band of the display - terrain, mountain background and all - is shifted by one pixel to the right. This is also present in the GUI, suggesting the possibility that WinUAE is not accurately displaying the wind and weapon power levels.

This glitch can appear to affect sprites at the half-pixel level, thanks to the Amiga's two default resolutions - Lores, which renders more-or-less square pixels, and Hires, which renders pixels at half the width, allowing for more horizontal detail.

This glitch also affects the brush in Graffiti mode.

Cause and partial fix

The cause of this glitch is the Resolution setting in the Display settings in WinUAE. By default, this is set to "Hires (normal)". By changing this to "Lores", the issue appears to resolve itself. The downside is that the main menu will be rendered at a lower resolution, and this may also affect other Amiga games, as well as Workbench.

Changing the Resolution setting to SuperHires results in a variant of this glitch that occurs on the quarter-pixel level, with Worms that come to a stop appearing to "settle" into a particular position that can be off by a quarter-pixel.

As yet, the relevant setting has not been found in FS-UAE.

TODO: Find out if FS-UAE has a comparable setting.