Subject: Meltdown programming tricks From: "Thomas Jentzsch" <tjentzsch@xxxxxx> Date: Wed, 25 Aug 2004 12:54:27 +0200 |
Hi, I don't know if anybody else has already looked into the Meltdown code. I got curious because it doesn't work perfect on emulators. The code is IMO quite sophisticated: 1. It uses selfmodifying code for kernel display! 2. It uses flicker for some quite effective anti-aliasing 3. Is uses a trick which is new too me to display two wide spaced AND double size players! Here is the code, which I suppose is responsible for that: 009e: ldx #04 ; two copies wide 00a0: lda #35 ; double sized player 00a2: stx NUSIZ0 00a4: sta NUSIZ0 00a6: lda #15 ; double sized player 00a8: sty GRP0 00aa: stx NUSIZ1 00ac: sta NUSIZ1 (AFAIK you can ignore the bits for missile size) So by switching the register to two wide copies and *immediately* after set switching to double size player, you seem to be able to combine both settings. Isn't that cool?!? Maybe it is also possible to combine other settings (e.g. quad size player and three copies wide) by using this trick. I'll start experimenting with that when I return home. Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ____________________________________________________ Aufnehmen, abschicken, nah sein - So einfach ist WEB.DE Video-Mail: http://freemail.web.de/?mc=021200
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