WIP: Cometfall

Mike · Post by **Mike** » Fri Jan 06, 2012 9:22 am

Kweepa wrote:The screen tear is because the scroll is unrolled once, so it scrolls the left and right at the same time. I agree it's ugly. I might revisit it. Perhaps try scrolling top to bottom rather than left to right (which would be slower, but more aesthetically pleasing).

That's the routine I use in you-know-where:

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.TScrollUp
 JSR TRange
 LDY y_top
.TScrollUp_00
 LDA $1100+ 0*192+8,Y:STA $1100+ 0*192,Y
 LDA $1100+ 1*192+8,Y:STA $1100+ 1*192,Y
 LDA $1100+ 2*192+8,Y:STA $1100+ 2*192,Y
 LDA $1100+ 3*192+8,Y:STA $1100+ 3*192,Y
 LDA $1100+ 4*192+8,Y:STA $1100+ 4*192,Y
 LDA $1100+ 5*192+8,Y:STA $1100+ 5*192,Y
 LDA $1100+ 6*192+8,Y:STA $1100+ 6*192,Y
 LDA $1100+ 7*192+8,Y:STA $1100+ 7*192,Y
 LDA $1100+ 8*192+8,Y:STA $1100+ 8*192,Y
 LDA $1100+ 9*192+8,Y:STA $1100+ 9*192,Y
 LDA $1100+10*192+8,Y:STA $1100+10*192,Y
 LDA $1100+11*192+8,Y:STA $1100+11*192,Y
 LDA $1100+12*192+8,Y:STA $1100+12*192,Y
 LDA $1100+13*192+8,Y:STA $1100+13*192,Y
 LDA $1100+14*192+8,Y:STA $1100+14*192,Y
 LDA $1100+15*192+8,Y:STA $1100+15*192,Y
 LDA $1100+16*192+8,Y:STA $1100+16*192,Y
 LDA $1100+17*192+8,Y:STA $1100+17*192,Y
 LDA $1100+18*192+8,Y:STA $1100+18*192,Y
 LDA $1100+19*192+8,Y:STA $1100+19*192,Y
 INY:CPY y_bot:BNE TScrollUp_00
 RTS

JSR TRange just fetches y_top and y_bot from the calling SYS statement, for a full screen you'd set y_top=0 and y_bot=184 (or use LDY #0 and CPY #184). With these parameters, the routine just needs some ~35000 cycles, and thus completes in 2 frames.

I'd rather have a single prg than a small file. Perhaps I'll run it through pucrunch to make the load times better.

You could pack the two files into a *.d64. Then you have a single file again, a convenient place for the savegame file, and the *.d64 is still small enough when zipped for transfer.

Kweepa · Post by **Kweepa** » Fri Jan 06, 2012 10:27 am

Lovely, I'll put that scroll function in! MG has some nice compact (and efficient!) code

I'd like to have a version that can be run in an on-line emulator. That's why I'm aiming for a single file. But I see the sense in a D64...

tokra · Post by **tokra** » Fri Jan 06, 2012 11:47 am

I'd prefer a single file as well if possible. Just easier to handle than a .d64 and if one wanted to transfer it to tape that would be possible as well. Using pucrunch or exomizer (which I prefer) all those 0-bytes are just happily crunched away

Kweepa · Post by **Kweepa** » Fri Jan 06, 2012 12:02 pm

tokra, I'm trying to use exomizer to crunch the prg, but the docs are rather confusing. Any chance you could give me a working command line? Ta!

tokra · Post by **tokra** » Fri Jan 06, 2012 12:43 pm

Yes, it's a little tricky. That's why I made my own example after I got it

A command line like:

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exomizer sfx 26603 -t52 -n auto.prg

has the following meaning:

sfx = create auto-start-program
26603 = this is the start address of the program after decrunching, eg. SYS26603 (you can use basic instead if you have a BASIC-program)
-t52 = sets decruncher target (52: Commodore Vic20, 32kB memory expansion)
-n = No decrunch effect (the VIC-20 programs are small so you won't even notice)
auto.prg = the program to crunch

Kweepa · Post by **Kweepa** » Fri Jan 06, 2012 12:58 pm

Ah yes.

Code: Select all

exomizer sfx basic -t52 -ocometfall_xmz.prg cometfall_propbeta.prg

Worked for me.
12.5k after compression!
Thanks!

Mike · Post by **Mike** » Fri Jan 06, 2012 3:19 pm

Kweepa wrote:MG has some nice compact (and efficient!) code.

Thanks! The scroll routine is not a permanent part of MG itself, though. Not all client programs would need a bitmap scroll routine. Rather it is part of the text display library for MG BROWSE, which can be linked to those programs which actually need that functionality. That way, there's no baggage of unused code around (and the MG core is only 1K in size).

rga24 · Post by **rga24** » Sun Jan 15, 2012 7:48 am

No idea what your memory footprint is, but you could squeeze 168*192 out of the VIC (21*12 in 8*16) if you can put the video matrix at $0200. That uses 252 characters with only 4 spare.

Kweepa · Post by **Kweepa** » Sun Jan 15, 2012 1:02 pm

Unfortunately the game uses a lot of memory locations in page 2, for file operations and the keyboard buffer for example.
I don't think one extra column is a big deal though.

Mike · Post by **Mike** » Tue Jan 17, 2012 1:56 pm

rga24 wrote:No idea what your memory footprint is, but you could squeeze 168*192 out of the VIC (21*12 in 8*16) if you can put the video matrix at $0200. That uses 252 characters with only 4 spare.

With a little more trickery, a program like MAXIGRAFIK does a fully bitmapped resolution of 208x256 pixels. However, it should give food for thought, that neither the graphic modes of MAXIGRAFIK, nor fcbpaint, and also not Picasso provide for much more than showing still images. If you're doing dynamic updates of the bitmap as it is being displayed, you're usually better off keeping most of the system area (i.e. the bottom 1K) untouched - at least if your graphics routines are working on application level and not in a demo.

darkatx · Post by **darkatx** » Sun Jan 22, 2012 8:44 pm

Finally beat the game!
Man this was so much fun - job well done.
Thanks Kweepa!

orion70 · Post by **orion70** » Mon Jan 23, 2012 5:15 am

I can't say the same - well it is fun indeed, but I didn't have time (or brain?) enough to beat it

. Anyway thanks again for that.

Peter · Post by **Peter** » Sat Mar 31, 2012 1:56 am

Great! Cometfall scores 89% in the latest Retro Gamer (issue 101).

Congratulations Kweepa!!!

Kweepa · Post by **Kweepa** » Sat Mar 31, 2012 10:50 am

Awesome news, thanks!
I won't be able to see the review for a while, as it takes about 6 weeks to get to the US.
Any chance of a pic?

Peter · Post by **Peter** » Sun Apr 01, 2012 1:20 am

Didn't have a scanner handy, so I took a picture of the review: