| 21-Feb-09 |
Atari XL/XE Space Harrier Conversion Project
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| Dec-03 | Jul-03 | Mar-03 | Jan-03 | Dec-02 | Jun-02 | Apr-02 |
21st February 2009
- Stage 6 and 7 completed
- Title screen
- High score entry and display
Here's a movie showing some of the new work. I like the quality of Vimeo, and I wanted to do some comparison movies, but I don't think I'll be able to put those on Vimeo, as they dislike video game footage (unless it's original work). There's quite a few Clips on YouTube of the original if anyone is interested enough, so I guess it doesn't really matter. I want to say thanks to the AtariAge members who uploaded last year's clips to YouTube after my dire experience of trying to have my ISP host the streaming media.
The game tries to create the illusion of more than the 4 colour per screen line limit at this resolution by dithering colours every TV frame (50 times per second for PAL, 60 for NTSC). Since the movies run at a slower frame rate than this, the frames had to be blurred together to see the extra colours on the movies. The net result of this is that the movies don't flicker like the actual game does, but they look blurrier.
Space Harrier Atari 8-bit Conversion Stage 6 and 7 from Chris Hutt on Vimeo.Creating the movies was a bit of a pain because of the interlace/dithering used by the game, but thanks to some fantastic free video processing software - VirtualDub and MediaCoder, I was able to get some half decent results. I was surprised to find out that the author of VirtualDub, Avery Lee, was an Atari 8-bit fan. He recently created his own Atari Emulator from scratch, just for fun and educational purposes! This guy is seriously talented. If you ever get to read this, thanks for the great software, Avery.
A few random comments as I'm reading back over my notes for the last year:
The original arcade title screen has some very nice spinning and slow zooming on the Space Harrier logo which hasn't been recreated exactly. If there's enough memory on the cartridge at the end of the day it might get redone.
The arcade game uses in-game sprites for doing most of the title screen. I decided to do the Atari version the same way - it's constantly clearing and redrawing the screen, which may seem a bit wasteful, but helps with the animations. Thought it might struggle with the frame rate with having several of the full size sprites on screen, but it is barely ticking over. In fact the frame rate had to be slowed down to make the logo zooming seem more sedate and leisurely, like the original.
Discovered the robot sprite had been scaled incorrectly ages ago, and was too big when seeing it on the title screen next to the one-eyed mammoth.
Never having written a high score entry screen before, I was slightly surprised at the amount of logic required to recreate the behaviour of the original arcade high score screen. In contrast the sorting and insertion into the high score table was much easier - only a single pass bubble sort is needed.
Only when I put an accurate countdown timer into the high score entry screen, did I realise that the music was much too slow compared to the original. It's better now, but maybe slightly too fast.
I couldn't overlay the high score entry screen onto the in-game screen as the original does, unless I went for a much chunkier font for the text. Keeping the same background colours seems a fair compromise though.
Never planned on doing a full attract mode, but the background colours from the title screen on the high score display don't look very good together. The original does a playthrough demo and then overlays the high scores on that when it is over.
Had to free up some memory and increase the number of simultaneous pattern handlers for an accurate recreation of the robots on Stage 7 that jump up to form a tower of robots. I had assumed they cheated in some way, and were really just following each other as nearly all the other patterns, but they don't.
Looks like I won't be able to have a completely seamless transition from one Stage to the next without a huge effort. The background graphics code needs to get generated for the next stage during the transition, and it's using a lot of the screen memory to do this right now. There may not be enough memory even on the 8Mbit cartridge if all the different backgrounds' code was pre-generated though! For now the plan is for just a text screen showing the number of the next stage using the nice double height and width font used by the original game. There is a preliminary version of it in the movie clip (showing just one letter).