Ironman Atari: A compilation of advanced Atari 8-bit programming techniques

[Rybags]

No idea how G2F implements it's priority emulation or if it's correct - I haven't really used it in a productive way.

 

That should be easy enough for someone to test.

 

I'll have to whip up a program later on the emulator, then verify on the real thing.

[Rybags]

 

pmgtest.zip

 

PMGTEST.BAS file contained in Zip.

 

 

Simple program shows the interaction between player/missiles and playfield.

 

Vertical stripes are Players and missiles with multicolour bit set and partial overlaps of PL0/1 and PL2/3 (and same again for missiles).

 

GPRIOR = $20

 

Horizontal stripes are Graphics 5 playfields 0, 1 and 2.

Top line of the text window changed to Graphics 12 (tall multicolour text) with some stuff printed to show interaction of Playfield 3.

 

Playfield colours left at defaults.

 

So, there should be about 18 or so colours visible on that particular screen, with no DLIs or other trickery. ed: actually, a bit less. Since the colour registers are ORed together, some of these combinations cause no change.

 

Note: picture is a screencap from real machine, white text added in Paint.

Edited April 10, 2008 by Rybags

[pseudografx]

So, there should be about 18 or so colours visible on that particular screen, with no DLIs or other trickery. ed: actually, a bit less. Since the colour registers are ORed together, some of these combinations cause no change.

In fact it is possible to put up to 23 colours on every line in ANTIC 4 mode, with no mid-scanline changes :-) The possibilities are interesting. We're experimenting with it right now...

[Heaven/TQA]

That is cool... i can not wait for PG gfx...

[NRV]

nice "graphic mode"

 

a fast test in the emulator:

 

 

and a fast test for the new lineUp 2.0

 

 

(well this mode is perfect for a Tetris..)

 

NRV

[analmux]

note however that colpf2 and 3 (mixing with PM2 &3) cannot both be used inside one character.

 

yeah, gprior possibilities give some nice and weird effects.

 

did anyone however notice that, using missiles in 5th player mode, you can mix them again in the gprior=48 mode with PM2&3? This results in an 8-colored sprite.....I didn't count the number of possible distinct colours (without DLI) yet

 

anyone ever noticed that colpf3 has in fact priority over the other colpf's? At least in 5th-player mode?

[NRV]

note however that colpf2 and 3 (mixing with PM2 &3) cannot both be used inside one character.

yeah.. the only mode that let you use colpf3 doesn't like that mix (I tried)

 

did anyone however notice that, using missiles in 5th player mode, you can mix them again in the gprior=48 mode with PM2&3? This results in an 8-colored sprite.....I didn't count the number of possible distinct colours (without DLI) yet

wouldn't that be 7 colored? 3 colors from pm2, pm3 and the "or" mix, plus the 3 colors from the "or" with "pm4", plus the pm4 color?

 

NRV

[analmux]

wouldn't that be 7 colored? 3 colors from pm2, pm3 and the "or" mix, plus the 3 colors from the "or" with "pm4", plus the pm4 color?

 

Of course

 

I counted the 'transparent' colour also.

 

You can get a nice rainbow-alike sprite by this trick. Especially nice when using quad-width and as underlays in hi-res gfx or textmode.

Edited April 14, 2008 by Analogue Multiplexer

[cas]

The content of IRONMAN Atari is now also available in the AtariWiki at http://atariwiki.strotmann.de/xwiki/bin/vi...G/Ironman+Atari

 

If you have any corrections or additions, and you do not like to edit in the wiki yourself, please send the changes to Marc or me. I will update the pages as new content comes in.

 

You can find a PDF version of the content in the attachment section of the page.

[Heaven/TQA]

that looks far more interesting than thought....