Green Hill Zone SNES port demo

Discussion in 'Engineering & Reverse Engineering' started by joyeux, Aug 13, 2020.

  1. MarkeyJester


    Vague Memories Resident Jester
    In my opinion, many of those affects can be achieved quite reasonably on the Mega Drive given the right circumstances:

    - Rotating bosses/backgrounds.

    The background rotations are usually the platform on lava (which can be achieved via H/V-scroll manipulation given it doesn't rotate further than what looks to be about 30 degrees), and the wheel with those rhinos (which is a little more complicated, but has been done before, and luckily the background is black in the boss, so a plane is free for this). The bosses themselves are usually very small sprite sized characters, so some art rendering can be done for those. The final boss with the ship can be done on a plane using slit scanning for various widths, and v-scroll manipulation for various heights.

    - Ghost house transparency

    This one would be an annoyance admitedly. The ghost itself in the secret boss could be done reasonably thanks to the fact that it's in a fixed non-moving room, art/palette manipulation can achieve it, but the ghost house's mist would have to be simplified in some way. I am wondering if the shadow/highlight with sprites would be an acceptable compromise, I mean, not many sprites load on-screen at once for SMW right?

    - Keyhole transition

    This would normally be an issue, except for the fact that the level graphics are very primitive and to me they look like they use very little colours or the colours are extremely similar, what could be done to some great success, would be fusing the FG tiles currently displaying onto the BG in a free VRAM space, and then using the FG with H-blank V-scroll manipulation to mask off the shape of the keyhole.

    - Pixelated transition

    This is probably the easiest within reason, iirc didn't Pier Solar do something similar? At any rate, H-blank V-scroll manipulation again.

    - Music/sfx might not be perfect

    You'd be surprised, I am confident the audio can be replicated to the point where you couldn't tell the difference unless you were to hear them side by side.
  2. Granville


    Yeah Pier Solar has a similar effect used for enemy encounter transitions (maybe elsewhere). It's a reasonable facsimile.

    There are several different transparency effects in the ghost houses. Two of which you mentioned with the Big Boo and mist. It should be noted that the Big Boo battle is accompanied by two smaller boos, which can also be positioned where they float on top of the transparent Big Boo sprite. Not sure if that would cause further complication. There's also transparent floating green bubbles in a few areas. Though the effect has issues and will actually mask out the foreground layer, you can only see the background layer through them.

    But there are also rooms with swarms of transparent small boo sprites. Over 20 can appear onscreen simultaneously. They can also turn opaque and rush at Mario.

    The sunken ship also has these boo hoards, and they can smoothly fade in and out of existence with transparency.
  3. Lostgame


    turntablist, dinosaur goddess Oldbie
    Toronto, ON
    The O.I.C.
    I mean, screen door transparency can work for this, and Sandopolis from S&K kinda has this same principle-ish...obviously the transparency won't be the same, but certainly this Sonic demo isn't 'perfect', either.

    There's some weird choices in this demo. Why the S3K item boxes? o.o
  4. Black Squirrel

    Black Squirrel

    this is what KLF is about Wiki Sysop
    I don't think anyone would really miss the transparency here - if there was a disappearing animation similar to Sonic & Knuckles' ghosts, I think that would be more than satisfactory (it might even look better(?!)).

    The problem will be the number of boos. IIRC most of them aren't sprites on the SNES - it's more hardware background effects.
  5. Techokami


    For use only on NTSC Genesis systems Researcher
    Sonic Worlds Next
    Yes there is!
  6. Granville


    They're all sprites. They disappear if you disable the sprite layer in a SNES emulator (and remain if you disable all of the 4 background layers).
  7. Black Squirrel

    Black Squirrel

    this is what KLF is about Wiki Sysop
    Fair enough. There's a playlist on YouTube that explains the SNES better than I ever could.
  8. Granville


    A new update was released-

    There's not a changelog, but some obvious improvements I noticed are as follows-

    -Sonic can now lose 32 rings
    -Powerups now work (shield, speed shoes, invincibility)
    -Released animals now hop around instead of falling offscreen
    -Swinging platforms now change direction smoothly
    -Sound effects now work
    -Sonic can now die (still can't game over)
    -The psudo debug mode was removed
    -MASSIVE performance boost.

    The last point cannot be understated. The SNES demo seems to maintain a comparable level of performance to the Genesis original, even when losing rings in notoriously stressful areas such as the spiked bridge and swinging platform (or the various enemy-dense areas around breakable cliffs and pits of spikes).
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