rotating blocks (with shadows) by RasterDream
screenshot added by rudi on 2012-11-17 22:24:22
platform :
type :
release date : november 2012
  • rulez 5
  • is ok 4
  • sucks 0
popularity : 0%
  • rulez 0.56
alltime top: #13880
added on the 2012-11-17 22:24:22 by rudi rudi

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ok, i tried to analyze this, just for fun:

Code: ; rotating blocks (with shadows) ; rudi of hxs^dke^rsd ; ; analyzed by vibrator^luaos (yeah it is a demo group too :)) *=$032c .word *+2 ; clever autostart sei ; no interruptions please while we do this shit lda #%11111111 sta $d015 ; turn all sprites on l: ldy #$70 cpy $d001 ; compare sprite #1 y with $70. (what?) beq *+2 ; change A only if last comparison not equal adc #$f5 ; A marches through its range in some odd pattern sta $d000 ; set sprite colors and positions (X and Y) in VIC ; lower byte of target address modified by sta below and #%11101111 ; skip some parts of VIC (D01x) to avoid too much mayhem sta *-4 ; modify VIC target address jmp l ; ...and loop

Is that about right? I think the smooth down movement and the sprite multiplexing is just a product of clever timing while writing weird shit to the sprite registers.

How long did you experiment?
added on the 2012-11-17 22:59:04 by vibrator vibrator
Yeah I'm bored :)
added on the 2012-11-17 23:00:06 by vibrator vibrator
I think it's the 'mayhem' instruction that does all the work ;p
added on the 2012-11-17 23:35:18 by Photon Photon
quite nice for 32b
rulez added on the 2012-11-17 23:59:16 by cruzer cruzer
vibrator: thats about right. i experimented not too long. i found these square sprites changing locations in a hurry most of the time. then i found these movements by accident.
added on the 2012-11-17 23:59:40 by rudi rudi
Sweeet... Quite a trick you pulled out. :)
rulez added on the 2012-11-18 12:48:20 by branch branch
added on the 2012-11-18 22:45:19 by BackSpace BackSpace
better :)
rulez added on the 2012-11-19 02:17:00 by neoman neoman
This is something interesting again. Now let's see who can open the sideborder in 32B. Cruzer? Are you there? ;)
rulez added on the 2012-11-19 08:43:17 by cryer cryer
rulez added on the 2012-11-21 10:41:17 by provod provod

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