[stella] Death Derby Milestone
Subject: [stella] Death Derby Milestone|
From: Glenn Saunders <mos6507@xxxxxxxxxxx>
Date: Mon, 24 Feb 2003 05:02:36 -0800
Okay, I've been holding off on posting to the list until I felt I made more
significant progress with the game. Since I haven't seen a post here in a
while, now might be a good time.
I've been corresponding back and forth with Thomas privately in order to
fix some of the remaining kernel glitches and they are all gone except for
one (which is probably a minor fix, read on).
I'm not ready to have end-users play with it yet on Atari Age, but I'm far
enough along that I'd like to solicit opinions from the list.
I've been adding in one feature a day to the code on average, so things are
moving along steadily.
For instance, take a look at how I did the score routine. I rolled this
one from scratch based on memories of reading disassemblies (for the
doubled characters and the masking). Anyway, I'm using indirect indexed Y
loads there and I know there is a faster way to do it. If there is a way I
could speed it up and drop the interlace and do all the work on one
scanline, it's worth pursuing. Note that I'm trying to use as little
vertical real-estate for the score as possible to make room for the cars.
If anyone has an example of a game that uses 3 2-digit score chunks using
players I'd take a look at that too. It's just that I'm trying not to have
to reposition the players during the active kernel, and I'm also trying to
be purposefully minimalistic to emulate the 1st generation game aesthetic
(in which case the score might remind you of something like Canyon Bomber).
But if the general feeling is that it would be better to do it with
sprites, to more closely match the coin-op score fonts, then I'll make an
effort to do that.
This current binary supports the Y-cable interface (maybe for now on let's
call it the GearBox adapter). Wiring information for this can be obtained
Right now the game only responds by toggling the blocks in the corners of
the screen to indicate forward or reverse gear. Tap forward to kick the
car into forward gear, tap back to go into reverse. A visual cue is
important since I don't want to force people to hold the joystick forward
or back to stay in forward or reverse gear. The joystick is just a latched
toggle switch. So I need something in the score to indicate that. If I
had used the difficulty switches, I wouldn't need the indicators as much,
at least if you were using a six-switcher ;)
The rotation of the cars is completely independent of the joystick
functions and they don't interfere with eachother.
I've also implemented the Color/BW switch for an authentic grey-scale display.
The current movement of the gremlins is probably pretty close to what it
will be in the finished game (although right now there is no AI so they are
just moving in a single fixed direction). It gives you a taste of the
stagger-step diagonal way they move, but I'm not at all happy with the way
the code handles the movement. It's pretty kludgy, but it works enough for
this demo. I'm hoping nobody notices so much that the vertical movement on
the gremlins is in 2-scanline jumps and that the gremlins never start on
the same scanline. Unless I slow the gremlins down any more than this, I
don't think the 2-scanline jumps are a problem. I also tweaked the running
animation and I'm hoping everyone agrees that these missiles really do look
like honest to goodness players. Because the animation of the legs is so
fast it almost looks like I'm painting both legs all the time but there are
frames where I'm just animating a single leg going through a sweeping
motion. There are only two extreme poses that feature two legs, one with a
leg outstretched forward and one with a leg outstretched backward.
Pressing fire on the driving controller will move either car up. I'm just
putting in the hooks for the controllers. I still have to work on a system
of animation that accounts for rotation and acceleration.
If anyone has some thoughts on how best to do that, please post them. I'd
love to hear it, and wouldn't want to have to reinvent the wheel.
The current glitch I have is when the green car crosses the top of the
screen it looks like its graphic isn't getting zeroed out properly.
If anyone (in addition to Thomas) could review the code, I'd appreciate it.
In the meantime, I'll be updating my journal pages. I've been too busy
coding day in day out to maintain the journal of late.
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