MAME Ms. Pac Man Issue

[FrizzleFried]

OK...I have been playing Ms. Pac Man for  years and this never happened once,  so it has GOT to be a MAME thing.

...I go through ghosts.  Thats right...3 times now I have been able to simply glide through a ghost.  It seems it happens when being chased and pulling a 180 degree reverse right through the sucker.

This has happened only on my MAME .108 vertical cabinet...I have yet to experience the same issue on my horizontal cabinet (but I don't play Ms. Pac on it any longer).

Anyone know of a documented issue with Ms. Pac with Mame .108?   I REALLY don't want to change versions...and lose all my hiscores....again.

[Hoopz]

I think it does NOT have to be a MAME thing.  I know that in playing both Pac Man and Ms. Pac Man, that going through ghosts is something that does happen on original boards.

[Dav]

OK...I have been playing Ms. Pac Man for  years and this never happened once,  so it has GOT to be a MAME thing.

...I go through ghosts.  Thats right...3 times now I have been able to simply glide through a ghost.  It seems it happens when being chased and pulling a 180 degree reverse right through the sucker.

This has happened only on my MAME .108 vertical cabinet...I have yet to experience the same issue on my horizontal cabinet (but I don't play Ms. Pac on it any longer).

Anyone know of a documented issue with Ms. Pac with Mame .108?   I REALLY don't want to change versions...and lose all my hiscores....again.

This is correct behavior.  The collision detection works by keeping track of what 8x8 pixel square all the objects are on.   So if you step off of your square onto a ghosts square and he steps off his square and on to yours simultaneously you didn't ever occupy the same square.

Dave

[Donkey_Kong]

Frizzle- Happens frequently back then (80's) and now on MAME. I like Davs technical explanation myself & I just thought I would chime in to reinforce that the behavior is normal. 

[FrizzleFried]

That is bloomin' strange....I must have pumped a couple hundred dollars in to Ms. Pac Man over the years and never once experienced that bug...

...and I can appreciate the technical explaination...and that would work if we were taking about an 8 pixel max opject....but I don't think that is the case here...anything larger than the size of the space being reported (in this case 8 pixels) would not 100% swap spaces and would therefore cause a collision detection...right? 

That said,  it is obviously normal behavior,  but perhaps not exactly for the reason Dev stated.

[Dav]

That is bloomin' strange....I must have pumped a couple hundred dollars in to Ms. Pac Man over the years and never once experienced that bug...

...and I can appreciate the technical explaination...and that would work if we were taking about an 8 pixel max opject....but I don't think that is the case here...anything larger than the size of the space being reported (in this case 8 pixels) would not 100% swap spaces and would therefore cause a collision detection...right? 

That said,  it is obviously normal behavior,  but perhaps not exactly for the reason Dev stated.

Regardless of the size of the sprite it has an exact pixel point coordinate location.  It doesn't check all points on the sprite; only the origin point of the sprite is converted to the grid squares. 

That's also the reason why sometimes you barely touch a ghost and die and other times you can be partially engulfed and still survive.


The reason most people don't see it is they don't usually charge head first into a ghost. 

[Hoopz]

The reason most people don't see it is they don't usually charge head first into a ghost. 

Hence why I see it all the time!   

[ppilot]

This is known as a 'booey', and there are even patterns that take advantage of it (I know a 9-key pacman pattern that has 4 booeys in it, it's great fun.)  More info here:

http://www.twingalaxies.com/forums/viewtopic.php?t=5727&view=next&sid=97bf758352a15ca0250daf2188d1196e

[FrizzleFried]

I dunno...I played a game this morning where it happened twice in a single game...and once when my Ms. Pac traveled a good inch toward the ghost first (not a direct switch of directions).

Being I don't think I had ever saw it before ... and now it is happening multiple times in a single game...something's GOTTA be up.

[Hoopz]

Why not post this over at the Mameworld forums???     

Seriously, why do you think it HAS to be a problem with Mame? Did you read the posting on the link at Twin Galaxies?

[FrizzleFried]

Mameworld forums is a touchy subject with me...

...and I did read the Twin Galaxies link...interesting stuff for sure.  I just find it to be quite out of the ordinary that for countless years I had not experienced this bug,  now I have seen it 5 times in a week,  twice in one game.

I guess it is my lucky week or something...because I had played Ms. Pac on my cabinet at least a hundred times prior without it happening.

Maybe I should go buy a lotto ticket today...

[Thenasty]

I just find it to be quite out of the ordinary that for countless years I had not experienced this bug,  now I have seen it 5 times in a week,  twice in one game.

You're catching up now......

Maybe I should go buy a lotto ticket today...

Good luck.... Don't forget us BYOAC users