Jump to content

Escape sprite handling glitch: Difference between revisions

A word.
>Bbbbbbbbba
(Added explanation.)
old->Bbbbbbbbba
(A word.)
 
Line 10:
To display the Start menu, the game needs to load the tileset used for text, which overwrites half of the tileset used for overworld sprites. Specifically, the "walking" frames of sprites are overwritten. NPCs respond to this by reverting to the "standing" state whenever the tileset for text is loaded. The player sprite does not check the tileset, but normally it's impossible to open the Start menu (or display any sort of text) in the middle of a player step, so it's not a problem.
 
The problem comes from the code that handles the animation of the escape item. The player is supposed to first spin in place for a while, then start to move up while continuecontinuing spinning. For both parts of the animation, the function SpinPlayerSprite is used to change the facing of the player. That function assumes that the 4 byte list wFacingDirectionList has been initialized to some cyclic permutation of $00, $08, $04, $0C (down, left, up, right), with hl pointing into somewhere into the list. This is indeed the case for the first part of the animation.
 
However, for the second part of the animation, hl is erroneously left pointing to somewhere else, namely, wPlayerSpinWhileMovingUpOrDownAnimFrameDelay. This value is explicitly set to 2 on SGB, and 3 otherwise. Therefore, SpinPlayerSprite would futilely shift wFacingDirectionList around, while setting the player's facing byte to $02 or $03 depending on the platform.
Anonymous user
Cookies help us deliver our services. By using our services, you agree to our use of cookies.