RE: Lunar Lander on Asteroids. :-)

> Lunar Lander does use the same landscape over and over again.
> I had thought about hacking it and making a random landscape (too bad
> there's not a pokey chip on LL, since there's not one, you would have
> to
> write a random number generator).
>
:-) Ahhhh, but I'm adding a POKEY for sound for Ast. Dlx anyway!
Pseudo-random number in there!

> Another option would be to have several landscapes prebuilt and just
> select
> from one of them. (this would be real easy, just start a counter from
> the
> time someone puts a coin in until the game starts, then just mask off
> the
> high bits and use the number to select the terrain)
>
Yeah, I was thinking along the same lines-- maybe add a "terrain select"
after coin drop...

> The only thing I don't know is how they do the collision detection (as
> well
> as the height above landscape), they either calculate it from the map
> or
> there is a table somewhere else in memory they use that matches the
> map. (If
> they do it from another table, it could be a real pain to change the
> landscape)
>
Affirmative. :-/ When I wrote Moon Lander for the Vectrex I had this
really hellish table system that pre-computed a bunch of stuff to reduce
the realtime math required. (Excel crunched the data from a spreadsheet
that I'd then cut and past into the code.) When digging through the
disassembly of LL I found a lot of large-ish data tables. I'm assuming
they're rise-run tables or something similar that they use for collision
detection and game logic.

I've got a lot of free ROM space in the LL memory map. Instead of
mirroring the "top" of memory on an Asteroids board (7800-7FFF) up into
F800-FFFF like the original hardware, I have my own ROM code up there.
I think it's probably safe to use all of 8000-F7FF too. So we could
make as many tables as we wanted in ROM, as long as we have a way to
index into them...

> Let me know if you want me to start hacking through the code (I can do
> this
> when I get board of working on my color space wars, and when I'm not
> doing
> homework)
>
Feel free to tinker around! (That goes for any/all of you.) MAME will
work fine for that. I can tell you where I think the tables are. A
fair first-test would probably just be to zero out the tables and see if
you can fly through the mountains...

There's some neat ideas for Asteroids "patches" floating around too--
rapid fire, smart-bomb instead of hyperspace, etc. (Smart bomb would be
neat, IMHO. Use the Pokey's pseudo random number generator to pick a
random number of rocks to "detonate" and then load the hit tables
simultaneously. Make some neat POKEY-sound to go with the carnage.
Lots of rocks simultaneously appearing and taking off in different
directions would probably make it a fairly dangerous move too. Maybe
limit it to once per "life" or something...)

-Clay
Received on Thu Feb 18 18:55:48 1999