Re-visiting Defender...

[RevEng]

26 minutes ago, ZylonBane said:

Jesus, some people really don't think before they post.

There's no reason to be so toxic. If you disagree, then state your reasons for disagreement, but there's no need to accuse the other person of idiocy. It's a cheap shot, and it says more about you than them.

[+Stephen]

28 minutes ago, RevEng said:

53 minutes ago, ZylonBane said:

Jesus, some people really don't think before they post.

There's no reason to be so toxic. If you disagree, then state your reasons for disagreement, but there's no need to accuse the other person of idiocy. It's a cheap shot, and it says more about you than them.

But that wouldn't be a ZylonBane post then - 20 years and counting

[Paul Westphal]

That type of toxic behavior is mostly why I do not reply to many posts. It’s very frequent in the Jaguar forums. It’s mostly ego based IMO. That being said, I applaud all the adults that can work together to solve problems while having mutual respect  for each other in the process. 

[Cris1997XX]

ZylonBane acting like a toxic twat? Nothing new to see her

[Zonie]

On 1/11/2022 at 10:25 AM, ZylonBane said:

Oh sure, throw out one of the most distinctive aspects of the original game, which is present in literally every port. Nobody would mind that.

 

Jesus, some people really don't think before they post.

Well excuse me, I did think before I posted. I literally don't pay attention to that scanner. Too much going on in real time. But hey, you're the expert.?

Just an option.

[kiwilove]

On 1/11/2022 at 1:38 PM, Synthpopalooza said:

I will still work on the Defender sounds, just in case Bob reconsiders.

I listened to some bloke who described in detail (above my head) about how the sound was generated in the Defender coin-op.  The sounds coming from that cabinet was so iconic - and you certainly know when Defender was being played.  To have any home version able to come close to the coin-op, is I think a massive achievement and I think it's brilliant to have someone keen on doing what they can with it.

I'm always in favor of fixing any flaws in the original.  Like there wasn't a fine scroll in the coin-op and home versions have a very jerky fast scroll.  I think Dropzone on the A8 shows how it should be done?  That programmer actually did work on a Defender game, that was demoed but very few people got to see it.  I think he then redid everything which then became Dropzone - changed it, so that he would not then infringe copyright with Defender.  Seeing that he couldn't make any money from his Defender conversion.

Seeing Defender 7800 would be very nice indeed - and hopefully some aspects of the 7800 could be taken advantage of and able to deliver a 7800 conversion that'll stand out.

 

Harvey

[GaryH917]

13 hours ago, Zonie said:

Well excuse me, I did think before I posted. I literally don't pay attention to that scanner. Too much going on in real time. But hey, you're the expert.?

Just an option.

I agree with Zonie 100%. Never paid attention to the scanner as there was always too much going on in the game plus hitting the buttons at the right moment. 8/83 and I got 739,000 on the 5200 version which I couldnt come close to now lol.

 

Edited January 27, 2022 by GaryH917

[+Stephen]

13 hours ago, Zonie said:

Well excuse me, I did think before I posted. I literally don't pay attention to that scanner. Too much going on in real time. But hey, you're the expert.?

Just an option.

 

11 minutes ago, GaryH917 said:

I agree with Zonie 100%. Never paid attention to the scanner as there was always too much going on in the game plus hitting the buttons at the right moment. 8/83 and I got 739,000 on the 5200 version which I couldnt come close to now lol.

 

I was never worth a crap at Defender.  When Defender 2000 came out on the Jaguar, many people played the 2000 version by only watching the scanner and not the main play area.  While it may not be used by everyone, not having the scanner in Defender would be like Battlezone without the vector graphics.

[desiv]

4 minutes ago, Stephen said:

not having the scanner in Defender would be like Battlezone without the vector graphics.

To be fair, there are some very fun versions of Battlezone that don't have vector graphics...   

 

[+sramirez2008]

2 hours ago, GaryH917 said:

I agree with Zonie 100%. Never paid attention to the scanner as there was always too much going on in the game plus hitting the buttons at the right moment. 8/83 and I got 739,000 on the 5200 version which I couldnt come close to now lol.

 

 

[+Cafeman]

Defender needs some form of the scanner.  It is crucially important near the end of a stage and mutants and baiters are after you. 

 

I've got some experience with the asm side but I dont understand why the powerful 7800 can't pull off the scanner. This is going to make me do some reading and research once I have the free brain cells. Would it be easier if the scanner blips used fewer colors?

[RevEng]

The difficulty is mainly a matter of having to do 42 point plots within one frame, in addition to regular game logic, in addition to DL updates for some on-screen subset of that 42, in addition to AI updates for all enemies, etc. It's a lot of stuff going on in any one frame, to be sure.

 

But the radar doesn't need to done all in one frame. The coarse resolution of of the scanner isn't sensitive to minor movement anyway, so updating at 15Hz will ikely be fine. If you have memory to throw at it (Bob decided he wanted a stock config) you can do double-buffering of the scanner, and you'll get no visible quirks at all. If you update at 15Hz without double-buffering, you'll get a bit of drift on the dots (enemies plotted on frame N+0 only scroll/move next on frame N+4, enemies plotted on N+1 only scroll/move next on frame N+5, ...). I don't think this drift will be too bad, but it's one of those things you need to try before making a final decision. (there's also some hacks you can do to avoid the radar drift)

 

If more CPU is needed, beyond the scanner, I think there's other optimisation that can be done for off-screen enemy AI. (e.g. double the distance at half the frame rate, or less)

 

The issue here is Bob has been running his engine too hard and too long while his wheels were spinning in the mud. We've all been there. But this isn't a matter of the 7800 being technically incapable of recreating the Defender radar. (see the Petscii Robots 128x64 radar/map, for one example)

 

[NIKON]

throwing my 2 cents worth in here....

 

Doesn't have to be perfect...just be fun. 

 

I know Bob is a perfectionist but, again, does not have to be perfect to be fun

 

Done

Cheers

 

NIKON

[+Karl G]

1 hour ago, NIKON said:

throwing my 2 cents worth in here....

 

Doesn't have to be perfect...just be fun. 

True...but the project does need to be fun for the developer. If a project becomes too frustrating, putting it aside is a good idea. Sometimes that leads to picking it up again later, and sometimes it just means pursuing other projects that are less frustrating instead. 

[Goochman]

Just curious - anyone know if the Arcade is frame perfect on the scanner - I doubt it is - My vague memories didnt rely on a baiter coming exactly when the scanner said it should -  more like its headed my way!

[+Cafeman]

My eyes can't tell if a blip's movement was delayed 1/60 of a second. 

[PacManPlus]

Hi guys - this is why I wanted to have a chat with Mr. Jarvis.  I wanted to find out his thinking of how he did things.  The reason I first got into the 7800 was because I wanted to fill two holes (ok that sounds a bit... creepy....) - namely Pac-Man and Defender which were only missing from the 7800.

 

Pac-Man I did in spades, and it's bothering me that after all of the games I've done, I 'can't' do Defender.  That being said, I have some ideas:

- I've already reduced the collision check for the player's shot to only screen objects (of which there are 16, and held in a different list).  Why I was originally the player's shot against all 42 objects was idiotic.

- I wanted to break up the scanner updates over 4 frames.  I divide the object's horizontal column (which itself is the horizontal position divided by 4) on the *planet* (which is 1024 pixels) by 4 to get the column in the scanner anyway, so breaking up 48 objects (the player will be done every frame) over 4 frames should help a lot.

- Possibly breaking up processing the off-screen enemies over a few frames (2 or 4, it depends).  They aren't seen except for in the scanner, and the landers are really the only ones that interact with other objects (the humanoids)

 

Things that I didn't consider:

- I need more player shots.  I only have room for 1 where I should have 4.  This will add to the issue.

- I do need 48 slots for enemies (possibly more), not 42.  I'll need more spaces for swarmers for when the pod gets shot.  This will also add to the issue.

 

So I kind of got discouraged for a bit.

 

However, I did get back to thinking about "Adventure III: The Quest For the Chalice":  I *really* want to use the separate dual scrolling screen kernel I came up with in this game.  But right now the terrain is hard-coded.  I need to convert it to RAM and compact it before I can start moving forward:

NOTE: The Intellivision graphics are place-holders.

 

...but I digress...

 

Anyway, here's where I am at with Defender so far.  The attract mode works nicely... but once you start the 'game' (all it is right now is vertical movement, forced right movement, player shot, and randomly placed enemies - with shot collision detection), you'll see some slowdown, ghost objects, and other glitches.

 

 

Defender.A78 Defender.BIN

Edited January 28, 2022 by PacManPlus

[RevEng]

Think big, Bob... you can fill all of the holes! ?

[+Stephen]

Awesome.  Sleep on it for a while, and you'll have some ideas I am sure.  I recently did this with some 8-bit code (VBXE).  Couldn't come to grips with some of the documentation.  But I found myself thinking about it every night while trying to fall asleep.  Finally I just sat down and did some coding, and voila, it clicked into place.

[+sramirez2008]

1 hour ago, PacManPlus said:

Anyway, here's where I am at with Defender so far.  The attract mode works nicely... but once you start the 'game' (all it is right now is vertical movement, forced right movement, player shot, and randomly placed enemies - with shot collision detection), you'll see some slowdown, ghost objects, and other glitches.

Still looks great!  Please take whatever time you need you to complete this game.  In the end, I'm sure it'll be the best home console version of Defender and it will exist for our beloved 7800.  Looking forward to jumping into the DeLorean and sharing this with my younger self. ?

[+darryl1970]

20 hours ago, PacManPlus said:

Hi guys - this is why I wanted to have a chat with Mr. Jarvis.  I wanted to find out his thinking of how he did things.  The reason I first got into the 7800 was because I wanted to fill two holes (ok that sounds a bit... creepy....) - namely Pac-Man and Defender which were only missing from the 7800.

19 hours ago, RevEng said:

Think big, Bob... you can fill all of the holes! ?

Haha! Nothing creepy here at all! LOL! ?

 

20 hours ago, PacManPlus said:

Anyway, here's where I am at with Defender so far.  The attract mode works nicely... but once you start the 'game' (all it is right now is vertical movement, forced right movement, player shot, and randomly placed enemies - with shot collision detection), you'll see some slowdown, ghost objects, and other glitches.

Thanks for sharing. Even bits and pieces are a bit of a dopamine rush.

[SlidellMan]

With all the great work you have done, I say take a break from it.

[+Allan]

Sorry. I couldn't help myself. It popped in my head when I read PacPanPlus' post.

 

 

[Almost Rice]

I'll just pop in the 2600 version of Defender Arcade.

[PacManPlus]

Just out of curiosity, is anyone very familiar with the source code for 2600 Stargate?  I'm curious on how Atari/GCC (whoever it was) did things, as they seemed to not have an issue.  I may use elements from that if so.

Even though I worked on 'Defender Arcade' (which started with Stargate), I didn't have a disassembly and was able to search for tables - that was most of what I changed.

 

The disassembly for the arcade Defender, while commented, isn't much in the places where I need to see what they did (i.e. enemy AI).  (Just for comparison, arcade Galaxian was *completely* commented; so much so that I could convert, line by line, the code from Z80 to 6502).