Difference between revisions of "Active sprites rendered one pixel to the right of actual location"

Revision as of 04:18, 1 July 2018 (edit (login required)) Squirminator2k (Talk | contribs) ← Older edit		Latest revision as of 15:20, 22 July 2020 (edit (login required)) Squirminator2k (Talk | contribs)
(5 intermediate revisions by the same user not shown)
Line 1:		Line 1:
	{{ParentArticle|[[Tricks and glitches (first generation)]]}}		{{ParentArticle|[[Tricks and glitches (first generation)]]}}
−	In [[WinUAE]], the sprites for worms, projectiles, mines and in-motion gravestones are 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 Once the object has stopped moving or is no longer active, the sprite shifts back to its "real" location.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.	+	[[File:WDC-halfpixel.jpg|200px|thumb|right|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 Once the object has stopped moving or is no longer active, the sprite shifts back to its "real" location.
−	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.	+	An extreme version of this glitch is also present in [[FS-UAE]], a multi-platform Amiga emulator, causing the [[Horizontal graphics distortion|entire horizontal space aligned with an object to jiggle or sheer]].
−	Curiously, this glitch appears to affect sprites at the ''half-pixel'' level. The Amiga's native "Hires" mode halves the horizontal width of pixels, resulting in rectangular pixels and more horizontal detail. WormsDC uses this mode on the menus, but appears to use the Amiga's default "Lores" mode in-game. It's therefore unusual that WinUAE and FS-USE would render this error at a Hires pixel depth, unless WormsDC is doing something sneaky with the screen mode.	+	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.		This glitch also affects the brush in [[Graffiti]] mode.
−	== Possible fix ==	+	== Cause ==
		+	This was caused by WinUAE's incomplete or inaccurate subpixel emulation. A partial fix for this issue at the time could be found in the '''Resolution''' toggle in the '''Display''' settings in WinUAE. By default, this is set to "Hires (normal)". By changing this to "Lores", the issue would be resolved, with the downside that the main menu will be rendered at a lower resolution, and this may also affect other Amiga games, as well as Workbench.
−	A temporary solution for this bug is to change the '''resolution''' setting on WinUAE's '''Display''' settings from "Hires (normal)" to "Lores". This resolves the issue in normal play but, as a side-effect, reduces the pixel depth of the menu interface.	+	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.
−	Changing this setting to SuperHires results in a version 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.	+	The issue is no longer present in WinUAE as of version 4.1.0.

---

Latest revision as of 15:20, 22 July 2020

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.

An extreme version of this glitch is also present in FS-UAE, a multi-platform Amiga emulator, causing the entire horizontal space aligned with an object to jiggle or sheer.

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

This was caused by WinUAE's incomplete or inaccurate subpixel emulation. A partial fix for this issue at the time could be found in the Resolution toggle in the Display settings in WinUAE. By default, this is set to "Hires (normal)". By changing this to "Lores", the issue would be resolved, with the downside 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.

The issue is no longer present in WinUAE as of version 4.1.0.