PM Graphics in Atari BASIC

[rdefabri]

I forgot how simultaneously frustrating and enlightening programming could be (although I suck, so it's more frustrating than enlightening).

 

Creating PM graphics in Atari BASIC is simple enough - the POKEs to set up virtually everything, including horizontal movement, are all there.  It's obviously vertical movement that becomes an issue, and standard practices yield a much slower moving sprite moving up / down.

 

There are known machine language VBI subroutines, and I can get them to work.  However, I have some issues when I determine a collision (in this case, PM0 to playfield) - if I end the program, the PM stays on screen and when I go to run again, the program is corrupted and/or doesn't run.

 

So a few questions - is there a standard way to clear all the memory out and reinitialize?  I've tried CLR, and even loops to zero out everything.  No dice.  The other question I have is that the VBI subroutines I've leveraged (mostly from Atari BASIC programming books) use lengthy DATA statements.  Not a big deal per se, but if I were ever to attempt a 10-line BASIC game, it's a non-starter...is there some simplified or smaller machine code subroutine to handle fast vertical movement?

 

I know the simple answer is to use a different BASIC.  BASIC XE and Altirra BASIC have built in PM commands that make it easier, but now I'm hellbent on doing this in BASIC.  Any advice?

 

[Preppie]

Machine language subroutines are not allowed in the 10 liner BASIC competition.

 

It's possible to use strings to move players faster vertically but it's a little tricky and has a lengthy setup routine.  Info can be found here: 

 

Or you could design a game around your limitations eg. just have players move horizontally.

 

 

 

 

[rdefabri]

1 hour ago, Preppie said:

Machine language subroutines are not allowed in the 10 liner BASIC competition.

 

It's possible to use strings to move players faster vertically but it's a little tricky and has a lengthy setup routine.  Info can be found here: 

 

Or you could design a game around your limitations eg. just have players move horizontally.

Yep I know you can't use machine language in 10-Liner, I kind of gave up on that until I can actually program something that works!

Edited February 20 by rdefabri

[Irgendwer]

31 minutes ago, Preppie said:

just have players move horizontally.

...or don't move them at all:

😁