[HN Gopher] Glider for Apple II
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Glider for Apple II
Author : rbanffy
Score : 101 points
Date : 2025-03-27 10:12 UTC (12 hours ago)
(HTM) web link (www.colino.net)
(TXT) w3m dump (www.colino.net)
| gxd wrote:
| Great work! I learned about this game just last week when reading
| "The Secret History of Mac Gaming". This looks like an excellent
| adaptation.
| jhbadger wrote:
| It is. If this had been available in the heyday of the II, I
| think it would have been quite viable as a commercial product.
| JKCalhoun wrote:
| Very cool. I'll have to get an emulator up and running to try it.
|
| Another wild one (back port?) was a small run a guy did for the
| Nintendo. Here's one on eBay for example:
| https://www.ebay.com/itm/186125162930
| wk_end wrote:
| (In case anyone doesn't look at/recognize the username, pretty
| sure this guy here is the developer responsible for the
| original Mac Glider!)
| nukem222 wrote:
| I was a big fan of glider pro, having been born long after apple
| ][s: http://macintoshgarden.org/games/glider-pro
|
| I would download it, but I wanted to be productive today.
| pkdpic wrote:
| Brings back good memories. But never thought to ask what a
| "defensive rubber" is...
| FabHK wrote:
| Amazing how they managed to make a whimsical, yet reasonably
| legible font with these few pixels.
| colinlm wrote:
| I didn't create it, it's Motter Tektura 9pt
| (https://fontsgeek.com/fonts/Motter-Tektura-Normal) and I
| manually fixed a few characters that looked bad at 9px.
|
| On the splash screen, it's just an image, made with Gimp and
| converted to HGR.
| retrac wrote:
| That's some wacky smooth animation for the Apple II. It's quite a
| feat to have multiple apparent sprites move so smoothly like
| that.
|
| Apple II high resolution graphics are 280x192 pixels stored in 8
| kilobytes at 2000 - 3fff or 4000 - 5fff. (With a fun interleaving
| where bits in memory are not in the same order as the bits on the
| display. Woz saved a few chips that way.)
|
| That is to say, there are no hardware sprites.
|
| The fastest way to clear the display is an unrolled loop in the
| form of LDA #0, STA $2000, STA $2001, STA $2002 etc. That works
| out to about 30,000 cycles which takes 30 milliseconds. A more
| plausible operation - displaying a whole-screen bitmap by copying
| it from another location in RAM to the framebuffer using a loop
| with indexes - weighs in at several hundred thousand cycles, or
| an appreciable fraction of a second.
| dekhn wrote:
| My initial imposter syndrome came from not being able to
| understand enough machine language and the Apple II graphics
| format to be able to duplicate Ultima IV (with simultaneous
| sound and animation).
|
| But this exists now: https://github.com/fadden/fdraw
| JKCalhoun wrote:
| Wild if Apple had had something like a library or framework
| with this kind of stuff in the Apple II days.
| jdswain wrote:
| Not at all the same, but they did have QuickDraw II for the
| IIgs. This library had the benefit of using the simpler
| IIgs graphics modes, avoiding all the Apple II weirdness.
| With a little bit of searching the source can be found
| online.
| AndrewStephens wrote:
| I had an Apple][+ and can confirm that the HiRes mode was
| devilishly difficult to work with, to the extent that even many
| commercial games had visible artifacts and flickering.
|
| These smoothly moving graphics over a background image would
| have blown everyone out of the water in 1982.
| deater wrote:
| having VBLANK available works wonders, see this double-hires
| code I just put together that only looks nice due to the
| magic of VBLANK on Apple IIe/IIgs (Apple IIc is much harder
| to get VBLANK from if you're playing music with interrupts)
| https://www.youtube.com/watch?v=1QwUGFDcQcI
| scarface_74 wrote:
| Now imagine working with the double hires mode with vertical
| interleaving that has already been discussed and horizontal
| interleaving between the main memory and bank switched memory
| to the higher 64K of extended RAM.
| thought_alarm wrote:
| This game achieves its smoothness by synchronizing to the video
| refresh. That's not a particularly challenging thing to do, but
| it wasn't a viable option for commercial games back in the day
| due to uncertainty of how to do it properly across the
| different Apple II models.
|
| Apple added VBL polling with the IIe in 1983, and then broke it
| a year later with the IIc. And an unfortunate typo in the IIc
| technical reference manual meant that developers couldn't
| figure out how to do it properly.
|
| The only official, cross-platform way to do it was through the
| mouse firmware, but most users didn't have the mouse hardware
| installed.
|
| This game uses the mouse firmware, if available (II+ w/ mouse
| card, IIc, IIgs), to generate VBL interrupts. On the IIe
| without a mouse card, it polls for VBL.
|
| By the way, if you're running this game on the Virtual ][
| emulator for MacOS, be sure to disable the mouse card. Its
| emulated mouse card only generates VBL interrupts at 30 Hz, so
| the game runs at half speed.
| tinmith wrote:
| I loved the original Glider game on the old Mac. Back in 1997
| when I was in undergrad I made my own port using ASCII art to run
| on the VT100 terminals we had at the time. When I started
| learning Android, I ended up writing a VT100 emulator with the
| NDK to bring it back to life on modern devices:
| https://github.com/waynepiekarski/android-glider
| spicybright wrote:
| I played sooo much glider in highschool study hall, although it
| was the windows version, glider 4.0
|
| I liked the gameplay so much I learned 6502 asm and coded my own
| version for the atari 2600. Nowhere near parity with the real
| version obviously, but I was able to make 3 screens with 1 to 2
| moving obstacles, and a clock collectable that did nothing.
| JKCalhoun wrote:
| Yeah, Gregg Bieser did the Windows port of Glider 4.0 for
| Casady & Green (back in 1991 or thereabouts).
| jdswain wrote:
| For anyone wanting to build sprite type code on the Apple II, you
| really should read this article in Byte magazine:
|
| Preshift-Table Graphics on your Apple by Bill Budge, with Gregg
| Williams and Rob Moore. A23 Move blocks of pixels across the
| screen with only 3K bytes of overhead
|
| It's kind of hard to find, it's in the December 1984 Byte
| magazine, but an additional magazine at the end of the PDF, Bytes
| Guide to Apple.
|
| At the time this was huge, Bill Budge was probably the most well
| known game programmer, so getting a look inside how he wrote code
| was a big thing.
|
| Of course, as mentioned elsewhere, graphics is hard on the Apple
| II because of the complex memory layout due to Woz wanting to
| save a few chips. This can be contrasted with the Atari and
| Commodore computers that had custom chips that made graphics a
| lot easier.
|
| https://archive.org/details/byte-magazine-1984-12/page/n397/...
| colinlm wrote:
| This is the scalable and hard way :) I had no memory pressure
| issue with this game so I went with preshifted shapes instead
| (as described in page 4 of https://mirrors.apple2.org.za/ftp.ap
| ple.asimov.net/documenta...).
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