Mark Wolfe Posted June 23, 2008 Share Posted June 23, 2008 There is a great twist I came across on a homebrew version of space invaders for Atari St, called simply: "Invaders" where the terrain your ship is on has peaks and valleys so it is uneven and it creates this great challenge for shooting down enemy invaders because you have to also traverse these hills at the bottom of the screen. I'd LOVE to see that feature added to more space invader clones and homebrews. Quote Link to comment Share on other sites More sharing options...
mimo Posted June 23, 2008 Share Posted June 23, 2008 There is a great twist I came across on a homebrew version of space invaders for Atari St, called simply: "Invaders" where the terrain your ship is on has peaks and valleys so it is uneven and it creates this great challenge for shooting down enemy invaders because you have to also traverse these hills at the bottom of the screen. I'd LOVE to see that feature added to more space invader clones and homebrews. Sounds like Wavy Navy on the Atari 8bit Quote Link to comment Share on other sites More sharing options...
HammR25 Posted June 24, 2008 Share Posted June 24, 2008 Put this on my CC2 at lunch. Man it's hard with moving shields. lol Great job so far Bob. I know I can look it up, but what settings did you use for menu.txt? I've got: 7800: Space Invaders INVADERS 7800_32K 78BIOS once Bob gets the High score cart stuff done it'll be: 7800: Space Invaders INVADERS HSC_32K HSC Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 24, 2008 Share Posted June 24, 2008 Wow, looking pretty good so far. I do hope it's possible to replicate the ripple effect as the full formation of invaders moves across the screen. This side effect of the limited blit speed of the original arcade hardware has become emblematic of the series. Even the various arcade sequels have preserved it. Quote Link to comment Share on other sites More sharing options...
PacManPlus Posted June 24, 2008 Author Share Posted June 24, 2008 (edited) Thanks for the compliments and pointers, everyone. New Version: - UFO appears about evert 25 seconds or so - UFO stops appearing when there are less than 8 invaders on the screen - Dual player mode shows both player's lives on either side of the screen - single and 2 player alternating have the level number at the bottom right of the screen (although it's in HEX for the moment; need to find a good routine for converting hex to decimal in assembler) - Game Over logic in place - Invisible Invaders added - Added time out on options screen @DracIsBack - yes, I did use 320A for this game @Zylonbane - thanks! I tried to do the 'ripple effect' (it's in my blog), but removed it as it took too many cycles to keep track of each line. The last invader ended up not being very fast. Also, I am using Character Mode for the invaders, and offsetting the starting x position to move the line. The result is I can't move a single invader per frame like the arcade does. I'm surprised nobody said anything about the 'upside down Y' in attract mode and how I changed the effect slighty. Keep watching; it will show up. Edited July 24, 2008 by PacManPlus Quote Link to comment Share on other sites More sharing options...
HammR25 Posted June 24, 2008 Share Posted June 24, 2008 (edited) Going back to the menu after playing a game in invisible mode makes the menu invisible. It certainly makes picking another game mode harder. lol Basically push down 3 times to get to the invisible invader line to switch it back. It's the third option. The first one gets ride of the points screen and the next two down pushes get you to the proper line. edit: just noticed the Y you were talking about. That's pretty cool. The "S" feature is cool too. I assume the real game does that. I wouldn't know though because 99.99999% of my space invaders experience has been with the 2600 version. Edited June 24, 2008 by HammR25 Quote Link to comment Share on other sites More sharing options...
keitaro Posted June 24, 2008 Share Posted June 24, 2008 It's very good to see new homebrews for 7800. Good work!! It's would be interesting including, as said before in other post, sequels like Space Invaders Deluxe, and the Midway's Space Invaders II (with 2 players versus ) A future cart release? Quote Link to comment Share on other sites More sharing options...
PacManPlus Posted June 24, 2008 Author Share Posted June 24, 2008 Going back to the menu after playing a game in invisible mode makes the menu invisible. It certainly makes picking another game mode harder. lol oops That's an easy fix. edit: just noticed the Y you were talking about. That's pretty cool. The "S" feature is cool too. I assume the real game does that. I wouldn't know though because 99.99999% of my space invaders experience has been with the 2600 version. Thanks. The extra 'S' is actually the extra 'C' in 'INSERT COIN' on the arcade game. Being that there are no coins in the home version, I made it an extra 'S' inn 'INVADERS' instead. The upside down 'Y' in the arcade is actually taken away (off the screen) by that invader, and then brought back in the correct orientation. I thought it would be cute to actually have him flip it in place instead. Quote Link to comment Share on other sites More sharing options...
Lord Helmet Posted June 24, 2008 Share Posted June 24, 2008 Great stuff Bob Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 24, 2008 Share Posted June 24, 2008 @Zylonbane - thanks! I tried to do the 'ripple effect' (it's in my blog), but removed it as it took too many cycles to keep track of each line. I'm not terribly familiar with 7800 programming, but this is surprising to me. I'm guessing you tried implementing each row of invaders as an independent character-mode sprite? If so, that seems like a simple task for MARIA. What was chewing all the cycles? Also, are the sound effects final? That buzzing noise when you fire just sounds... wrong (I have a Space Invaders Part II machine, so the sounds are kind of burned into my brain). Probably not helpful, but it looks like this guy is working on emulating the original analog sound circuitry in software. Yikes. Quote Link to comment Share on other sites More sharing options...
Jess Ragan Posted June 24, 2008 Share Posted June 24, 2008 Niiiiice! I'm glad you went with a straight translation, rather than taking artistic liberties with the source material like the 2600 and 5200 versions of Space Invaders. Quote Link to comment Share on other sites More sharing options...
NE146 Posted June 24, 2008 Share Posted June 24, 2008 I have a Space Invaders Part II machine Nice! Space Invaders Part 2? Or SI Deluxe? And is it a cabinet? Cocktail? Pics! Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 24, 2008 Share Posted June 24, 2008 Nice! Space Invaders Part 2? Or SI Deluxe? And is it a cabinet? Cocktail? Pics! You're asking if my Space Invaders Part II is a Space Invaders Part 2? Also, yes, it's a cocktail model. Paid $100 for it, many years ago. Works perfectly. Quote Link to comment Share on other sites More sharing options...
gambler172 Posted June 24, 2008 Share Posted June 24, 2008 It's very good to see new homebrews for 7800. Good work!! It's would be interesting including, as said before in other post, sequels like Space Invaders Deluxe, and the Midway's Space Invaders II (with 2 players versus ) A future cart release? Hi And do not forget the Space Invaders "Time Attack" with different Invaders..... greetings Walter Quote Link to comment Share on other sites More sharing options...
PacManPlus Posted June 24, 2008 Author Share Posted June 24, 2008 (edited) I'm not terribly familiar with 7800 programming, This is my issue as well. I'm still learning, so I may not have done this the most efficient way. I'm guessing you tried implementing each row of invaders as an independent character-mode sprite? If so, that seems like a simple task for MARIA. What was chewing all the cycles? It wasn't that - Once one invader was left, there was so much checking going on (top line, bottom line, frame number, which line to move, the DLL for that line, etc.) that the last invader did not move fast at all. So I had to scrap. I am, however, using each row as an independant character-mode sprite like you said. I couldn't move each invader on a separate frame like the arcade. Also, are the sound effects final? That buzzing noise when you fire just sounds... wrong (I have a Space Invaders Part II machine, so the sounds are kind of burned into my brain). Buzzing? I tried to get it as close as possible (with the TIA) to the sound of the shot in the arcade... There shouldn't be a buzzing Was that on the real thing or an emulator? Probably not helpful, but it looks like this guy is working on emulating the original analog sound circuitry in software. Yikes. Yikes is right. I am always envious of people like that. BTW, thanks for the additional compliments, guys. Bob Edited June 24, 2008 by PacManPlus Quote Link to comment Share on other sites More sharing options...
NE146 Posted June 25, 2008 Share Posted June 25, 2008 (edited) Nice! Space Invaders Part 2? Or SI Deluxe? And is it a cabinet? Cocktail? Pics! You're asking if my Space Invaders Part II is a Space Invaders Part 2? No.. I'm asking if it's a Taito Space Invaders Part 2. Or a Midway Space Invaders Deluxe. There are a number of differences in the game (200 vs. 500 pt UFO's for example. Also the 1st level the invaders split, etc.). Not to mention if you look at the mirrored holographic upright versions of the game, there are a large number of differences in the artwork and colors itself. Different moons, different bezels, different backgrounds. etc. But yeah.. it's no biggie. I like Space Invaders. You said you had one. I'm just asking which one, because I think it's cool. Easy Edited June 25, 2008 by NE146 Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 25, 2008 Share Posted June 25, 2008 (edited) Once one invader was left, there was so much checking going on (top line, bottom line, frame number, which line to move, the DLL for that line, etc.) that the last invader did not move fast at all. I don't get this. The fewer invaders are left, the fewer sprites there are to process, right? It sounds like you're calculating a lot more stuff every frame than you should need to. Like, how are you currently figuring out when the formation needs to change direction? Worst-case, you could include a custom kernel for the last invader. Buzzing? I tried to get it as close as possible (with the TIA) to the sound of the shot in the arcade... There shouldn't be a buzzing Was that on the real thing or an emulator? I tried it in MESS. And by buzzing, I meant that sound kind of like what Centipede uses. The thing with the Space Invaders shot sound is that it doesn't modulate the pitch, like you're currently doing. It holds a steady pitch (of some annoyingly complex waveform) and volume level for ~0.13 seconds (about 8 NTSC frames), then decays to silence over the next ~0.16 seconds (around 10 frames). Hey, have you written to Opcode about this? Around the time he was working on Space Invaders Collection, I seem to recall him mentioning that he had a commented dissassembly of the arcade source code. Nice! Space Invaders Part 2? Or SI Deluxe? And is it a cabinet? Cocktail? Pics! You're asking if my Space Invaders Part II is a Space Invaders Part 2? No.. I'm asking if it's a Taito Space Invaders Part 2. Or a Midway Space Invaders Deluxe. I've already said twice that it's a Space Invaders Part II. So I'm really confused why you keep asking. Edited June 25, 2008 by ZylonBane Quote Link to comment Share on other sites More sharing options...
NE146 Posted June 25, 2008 Share Posted June 25, 2008 I've already said twice that it's a Space Invaders Part II. ok! Nice Quote Link to comment Share on other sites More sharing options...
Shannon Posted June 25, 2008 Share Posted June 25, 2008 I agree about the shooting sound and like Zylone tried it in a MESS based emulator, not a real thing. I do have a CC2 somewhere though. Can't seem to remember where I put it. There were a couple other odd little "quirks" that occured when quitting in the middle of a game and going back to the main menu. Although I honestly do not remember what they were. Just figured I'd mention so people could keep an eye out for them. I think in one case the sound didn't turn off (whatever channel is used for the thump, thump, thump). Quote Link to comment Share on other sites More sharing options...
mimo Posted June 25, 2008 Share Posted June 25, 2008 Hey Bob, fantastic work as always. Just to let you know I found no buzzing noise on the real thing. Also it plays ok on a PAL 7800 with the usual graphic glitching at the bottom of the screen and the colours being off. On a PAL system the menu was seriously hard to read as the red that you are using turns a dark brown. Also the blue invaders turn yellow. I know that you have not mentioned PAL, but I thought I would let you know. Quote Link to comment Share on other sites More sharing options...
TrekMD Posted June 28, 2008 Share Posted June 28, 2008 This game is amazing! Well done. Quote Link to comment Share on other sites More sharing options...
PacManPlus Posted June 30, 2008 Author Share Posted June 30, 2008 (edited) Thanks again guys, and thanks for the PAL test, Mimo. I'll work on fixing that once I have a complete game going. I want to try and make it auto-detect. Sorry for the lack of updates. Some real life issues going on here... That being said, I do have an update: - Bonus Life awarded at 1500 points - Pause now works - Local High Score (not HSC) works - 2 Player Alternating game works - Fixed the bug where making the invaders invisible made the options screen invisible - Added a 'No Shots' (children) option. SHOT SPEED: Normal, Fast, or None (thanks, Allan) Things Left: - Tweak Invader Bomb placement, frequency - Invader Bomb / Player Shot collision - High Score Cart - Invader / Shield Collision - Possible tweak shot sound One thing I need to do, is to figure out how to clear the stack that holds the return address for a subroutine. There are a few places where I had to 'jmp' out of a subroutine that was called with a 'jsr', and I don't want to end up with an overflow. BTW, you guys have to see the AWESOME artwork (again) done by Atariboy2600. Edited July 24, 2008 by PacManPlus Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 30, 2008 Share Posted June 30, 2008 One thing I need to do, is to figure out how to clear the stack that holds the return address for a subroutine. There are a few places where I had to 'jmp' out of a subroutine that was called with a 'jsr', and I don't want to end up with an overflow. Why can't you just pull the return address off the stack? All JSR does is shove the program counter onto the stack before performing an implicit JMP. Quote Link to comment Share on other sites More sharing options...
Shannon Posted June 30, 2008 Share Posted June 30, 2008 (edited) Yeah I was thinking the same thing... Or have it jmp to a rts statement... An indirect jmp can typically go 256 bytes right? Or is it 128 either way.. Edited June 30, 2008 by Shannon Quote Link to comment Share on other sites More sharing options...
ZylonBane Posted June 30, 2008 Share Posted June 30, 2008 An indirect jmp can typically go 256 bytes right? Or is it 128 either way.. An indirect jump can go anywhere in memory. What you're describing is a branch. Quote Link to comment Share on other sites More sharing options...
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