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AA in the house

Posted by SpiceWare, in Draconian 11 June 2017 · 591 views

Got quite a bit done the past few days!

  • AtariAge logo in place.  Not tune yet, so it's blink and you'll miss it ;)
  • fixed the screen roll issue on B-8.  It was due to left over code from this build, which took 6+ scanlines of time to set the positions of the objects during vertical blank.  This was no longer needed as object positions are now set during the first 5 scanlines of the game screen.
  • fixed the graphic glitch at bottom-right of gameplay area.  The repositioning of the players to draw the radar was occuring 1 scanline too soon.
  • Fixed a problem where the new mine explosions were not deadly on the right half of the explosion.  Problem was caused by the collision detection routines only supporting line-by-line shifting of the station sprites.
  • Added support for "tunes" - basically 2 sound effects that play concurrently on both channels.
  • iesposta's finished the sound effects for Player Shoots, Missile Spy Ship Hit, and Cannon Hit.  All are in place, though Missile Spy Ship Hit isn't used yet as that part of the game has yet to be written.
  • iesposta's finished the tune for Round Clear
  • Revised end-of-round logic to freeze the player's ship, remove all enemy ships, remove all station shots, and play the Round Clear tune.
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I've been doing more play testing in MAME to get a handle on how the game plays (it's difficult to write game code when you don't know the rules!). I plan to post a blog entry in the next day or two which documents what I've figured out so far. I would appreciate feedback on anything I get wrong or haven't yet figured out.
Additionally cd-w's been working on the driver trying to fix the boot problem with the Evil 7800s like mine.  It's possible the final solution will require an update to Stella as well.
For Harmony or Stella (requires Stella 5.0.0-pre8 or newer)
Attached File  draconian_20170611.bin (32KB)
downloads: 24

Have you ever taken your evil 7800's apart?  I'd love to take a look at some high-res pics of those boards.


I like the NTSC logo the best, it is super close.

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Love the sound effects and attention to detail, like the ghost of the pilot flashing when your ship gets all blowed up!

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Love the sound effects and attention to detail, like the ghost of the pilot flashing when your ship gets all blowed up!


Thanks - although I'm not sure what it was really supposed to be. It's in the arcade explosion though, so I kept it. It almost looks like a leftover graphic from some other game:



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I took my 7800 apart once when I was going to attempt an AV mod.  Decided not to do it, and closed it back up.  When I get a chance I'll open it back up and take some photos.
The colors for NTSC are 0x36 and 0x96. For PAL and SECAM I use color conversion functions.  For PAL I use this:
const unsigned char NTSCtoPAL[16] =
  // SeaGtGruff's conversion values from this post at AtariAge:
  // http://atariage.com/forums/topic/165424-modify-colour-palette/?p=2043124
  0x00, 0x20, 0x20, 0x40, 0x60, 0x80, 0xa0, 0xc0,
  0xd0, 0xb0, 0x90, 0x70, 0x50, 0x30, 0x30, 0x20

int ColorPAL(int color)
  return NTSCtoPAL[color>>4] +    // chroma value
  (color & 0x0f);          // luma value
For SECAM I use:
const unsigned char NTSCtoSECAM[16] =
  0x0e,   // 0 = white            e = white
  0x0c,   // 1 = yellow           c = yellow
  0x0c,   // 2 = yellowish orange c = yellow
  0x04,   // 3 = reddish orange   4 = red
  0x04,   // 4 = red              4 = red
  0x06,   // 5 = reddish purple   6 = purple
  0x06,   // 6 = purple           6 = purple
  0x06,   // 7 = bluish purple    6 = purple
  0x02,   // 8 = blue             2 = blue
  0x02,   // 9 = blue             2 = blue
  0x0a,   // a = bluish cyan      a = cyan
  0x0a,   // b = cyan             a = cyan
  0x08,   // c = green            8 = green
  0x08,   // d = green            8 = green
  0x08,   // e = olive green      8 = green
  0x0c    // f = brown            c = yellow

int ColorSECAM(int color)
  if (color < 2)
    return 0;   // return black for 0 or 1
    return NTSCtoSECAM[color>>4];
Hmm, reminiscent of the Enterprise - wonder if that's what the player's ship looked like in early versions.
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It almost looks like a leftover graphic from some other game:


From StrategyWiki:

Note: If you watch the Star Fighter explosion carefully, you will see the original Galaxip explosion from Galaxian.
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Not completely buying it...



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Yeah, that's doesn't look right.  Maybe it was from Galaga, I seem to recall it had an unused sprite that was similar to the Enterprise.

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It's not the Galaga explosion...




But a very similar sprite is in there (note also a close cousin to the Bosconian Spy Ship):



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