Subject: Re: [stella] the B. Watson's problem...|
From: "B. Watson" <atari@xxxxxxxxxxxxxx>
Date: Mon, 20 Aug 2001 09:50:37 -0400 (EDT)
On Mon, 20 Aug 2001 cybergoth@xxxxxxxx wrote: > Hi B. Watson! > > > <snip> > > Some comments: > > - This isn't really a 2-line kernel, it's just a *forced* one. > You're doing only one line and expand it via the second STA WSYNC. > > - To avoid your problem, you can do the playfield on the first line and the sprites on the second for example. D'oh! > > - Having both sta HMOVE & sta HMCLR inside the kernel is senseless > (in your case). Do that once outside the kernel. > double D'oh! > - Learn how to enable the missile via PHP, find the trick in the combat > source for example. All your branching would be reduced to > > cpy evpos > php > > if the stack is set/reset properly before and after the kernel > hmmmm... > - Learn how to display sprites properly via subtractions, there's > no need to have tons of bytes zeroed out in the ROM. Find > examples of this technique in the Stella archive under the > 'Gunfight' topic. Thomas posted some detailed hints *how* it's done > there. Find it utilised in (some :-)) Gunfight sources as well. > Yeah, the zeroed bytes seemed wasteful, also in an early version they caused me grief because they crossed a page boundary.. At the moment, I'm late for work, but when I get home I'm going to sit down with your email and my code and spend some time cleaning house. I just wish I could get this kind of useful advice in code reviews at work! Actually... I spent a lot of time yesterday figuring out how to get multiple moving objects (re-use both players 6 times, one ship and 5 enemies)... The source is a complete mess right now, but I'm attaching a rom image to this message, if anyone has time to look at this, let me know what you think... Thanks, Brian --- If a trainstation is the place where trains stop, what is a workstation?
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