C64 Games memories International Karate Plus

In this episode of Commodore 64 retro games memories, I look at IK+ (International Karate Plus), the graphics data layout, how the player characters are drawn, and reverse engineer some of the animation code.
github.com/martinpiper/Debugg...
00:12 Introduction
00:40 Sprite grids and characters
02:40 Examine the sprite updates
04:18 Quite a lot of memory updates
04:50 Graphics data memory layout
05:33 Double buffered rendering
06:28 Three duplicate characters
07:49 Several frames to calculate
08:29 Game memories
09:30 Analyse animation code
28:52 Writing debug code

[@cpu_UP]

I spent ages trying to figure out how all players were drawn. Tried only sprites multiplexed. Character based players, bitmap drawings. None was a good approach. The mix of the techniques was the solution. Thanks for soling a mystery I had for about 40 years.

[@Sumaleth]

That is a lot more complex than I'd always assumed. But very cleverly done too.

[@3vi1J]

Love your insights. Awesome investigation, as usual.

[@MartinPiper6502]

Thank you for your support :)

[@cpu_UP]

I always tried to understand how the characters were drawn. I checked only sprites, only character, and bitmap approaches. None was good enough to draw everything. Mixing the modes was the trick. Thanks for solving a mystery I had for about 40 years.

[@cpu_UP]

Thanks!

[@MartinPiper6502]

Thank you for the support

[@agpxnet]

IK+ is my favorite fighting game of all time. Technically it's impressive, the graphics, the animations are excellent, the dynamics of the game are formidable. I've always been curious about the algorithm that makes opponents move: it's truly remarkable, but I've never found an explanation on the internet.

[@LogrusUK]

Awesome.

[@MartinPiper6502]

Thanks!

[@PeranMe]

It’s been a while since I played the first International Karate, but listening to IK+ here, I can’t help but wonder about the sample playback; the IK+ samples feel dirtier. I’m not read up enough on the CIA chips to suss out the sample rate myself, but maybe that would be a fun summer project :-) The original IK clearly used samples taken from the brilliant movie ”Enter the Dragon”, but I suspect that’s common knowledge these days. Anyone know if the IK+ samples came from there too? Anyway, thanks for another great video, IK+ is one of the C64 games I seriously doubt can be bested, even with all the tools and experience we have today. Archer was one-of-a-kind.

[@stevethepocket]

Something you did made a little worm start crawling across the screen at 31:32. It actually popped up before you paused.

[@MartinPiper6502]

The worm, jumping fish, birds are all part of the "random" triggers in the background.

[@ArneChristianRosenfeldt]

Looks like VIC should have laid out sprite patterns in a hidden graphics screen with 40*25 chars. Or 39*25

[@beelinkk]

so cool

[@NorthWay_no]

How about looking at Bubble Bobble? It should have some interesting software sprite work going on.

[@MartinPiper6502]

This will be next.