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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
00261 Graphics Minor Have not tried Jan 28, 2008, 01:01 Nov 26, 2016, 18:56
Tester Frotz View Status Public Platform
Assigned To Resolution Open OS
Status [?] Confirmed Driver aerofgt.cpp
Version 0.37b4 Fixed in Version Build
Summary 00261: karatblz: Right at the beginning, the heroes are introduced using a zoom effect. Several frames are glitched.
Description Right at the beginning the heroes are introduced using a zoom effect. Several frames of the zoom effect are glitched. It looks as if the image was cut into rectangular jigsaw pieces and then re-arranged with all pieces slightly out of place.
Steps To Reproduce
Additional Information
Regression Version
Affected Sets / Systems karatblz
Attached Files
png file icon karatblz337b4gre_shot1.png (7,074 bytes) Feb 14, 2008, 08:37
png file icon karatblz337b4gre_shot2.png (5,260 bytes) Feb 14, 2008, 08:38
There are no relationsihp linked to this issue.
User avatar
Apr 3, 2008, 15:25
the problem is the routine to use for handle the zoom with multi-sprite

actually in mame there's a linear conversion (with a wrap):
((oy + zoomy * y / 2 + 16) & 0x1ff) - 16;
in other words the "x distance" from sprite #1 to sprite #2 :
for zoom = 0 is 16
for zoom = 1 is 15,5
for zoom = 2 is 15
and so on (step = 0.5, constant)

for a perfect zoom it's necessary to use a non-linear conversion
the "x distance" from sprite #1 to sprite #2 :
for zoom = 0 is 16
for zoom = 1 is 15
for zoom = 2 is 14,125
for zoom = 3 is 13,25
for zoom = 4 is 12,75
for zoom = 5 is 12,125
for zoom = 6 is 11,5
for zoom = 7 is 11,125
for zoom = 8 is 10,5
for zoom = 9 is 10,125
for zoom = a is 9,75
for zoom = b is 9,375
for zoom = c is 9,125
for zoom = d is 8,625
for zoom = e is 8,375 (guessed, not used in the game)
for zoom = f is 8,125 (guessed, not used in the game)

yet, i'm not sure if these infos can be used in a acceptable fix
can i have a feedback by a dev?
User avatar
Apr 3, 2008, 15:51
Brought to top of list - was added while I adjusted dozens of bugs with the galaxian/galdrvr changes.
User avatar
Aug 3, 2009, 12:44
I don't know if the rectangles effect is wrong or not (low quality video), but the wobbly effect during zoom is definitely wrong.

Karate Blazers video from PCB:

Karate Blazers video from MAME:
User avatar
Aug 3, 2009, 13:29
There also seems to be a slight pitch difference in MAME (a bit higher) than PCB recording.
User avatar
Nov 22, 2016, 06:28
Here is an original PCB video of the Japanese version at 10% speed, sprite scaling is smooth not like MAME. Removing the possible tag.
User avatar
Senior Tester
Nov 22, 2016, 20:28
I believe there used to be a table in MAME to make this case smooth, but somebody (Nicola?) decided it was incorrect and removed it / suggested that drivers using the non-linear zoom table needed upgrading to the linear one (which causes these glitches)

it could be a difference between the older / newer video system sprite chip of course.
User avatar
Senior Tester
Nov 26, 2016, 18:56
The bug has always been present, since the game was added and the zoom table was used. Re-implementing it now (which is just a couple of line changes) doesn't fix the problem. I guess robiza table should be used or at least the info he provided implemented in a some way.