Subject: Another Berzerk discovery...at least for me :-) From: "Dennis Debro" <dennis@xxxxxxxxxxxxxxx> Date: Wed, 17 Nov 2004 12:33:11 -0800 (PST) |
Hi there, I was looking at Berzerk again and I see Dan used fractional positioning to help keep the game speed consitent between NTSC and PAL :-) This is the first game I've disassembled see do this. Here is the player movement code... lda playerMotion ; get the player's fractional delay clc adc #PLAYER_FRACTIONAL_DELAY sta playerMotion bcc LF42C PLAYER_FRACTIONAL_DELAY is 112 for NTSC (i.e. 7*256 / 16 -or- move 7 out of 16 frames) and 134 for PAL (i.e. [7*256 / 16] * 1.2 adjusted for 50 frames per second). He does fractional positioning for the missile movement too. I'll try to push to finish this listing quickly because it's pretty nice and I'd like to share it. Take care, Dennis
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