Noob Atari 8-bit development and graphics questions

[emkay]

How about a question? If the screen has to be 3 times bigger, what is it worth, if a pixel can have the double resolution?

[Alfred]

It's only funny if I knew what you were talking about. I'm assuming the larger image with the two characters is the C64 and the purple thing is the Atari, since you said the image with the two characters had never been done on the Atari. As for the rest, I really have no idea what you're on about. I find it hard to believe that you can have a scrolling background with characters and have character-based players in the foreground. You would need dozens if not hundreds of copies of the player characters to match the background character that was behind them every frame, I imagine you'd run out of memory.

 

The image looks nice, but I still don't see how you can animate your player character horizontally say, a pixel width at a time without needing a huge number of characters. E mode allows this, it just swaps space for time, but time is (almost) unlimited, space is not.

[R0ger]

Why mode 4 ? Every color counts, and you use tiles for the map anyway.

You can still move enemies and objects smoothly, with some extra processing. But you have to do the processing in bitmap mode too. You can merge the enemies with background. Again, it's about the same as with bitmap mode. Character mode eats a bit more DMA, and you will most likely need some DLIs (or many), but the extra color is imho worth it.

 

Btw. international karate is in character mode. With shifting and background merging (background being the other character). Games like these will never be 50/60 fps, but you don't really need that.

[Turbo Laser Lynx]

8 hours ago, carlsson said:

Not sure if the Channel F is unknown really. Pretty well documented with development resources, all games dumped and emulated, rather big company who stood behind it etc. A couple of years ago a lengthy article was posted about the origins, how it started as a video game using the Intel 8008 or possibly 8080 (a bit unclear) and when the developers approached Fairchild, had to adopt it to use their own F8 CPU instead.

 

Colour computer graphics in general probably predates a little earlier, though it was a matter of making it practical and economical. I found the Cromemco Dazzler from 1976, an add-on card to S-100 bus machines like the Altair 8800. It generates colour graphics before the Apple II, though at a lower resolution.

 

It came bundled with this kaleidoscope program:

 

 

 

Hey thanks! Interesting stuff! I hadn't heard about the Fairchild until a couple of months ago, so perhaps I put a little bit too much weight on my own experiences

 

3 hours ago, Alfred said:

 Why all the obsession with Antic 4 ? I get it about the 5 colours, but it's character based, so either you can only have 4 single colour players, or more likely two multi-colour players. Any enemies would have to be animated via character set and means they'd have to be full cell-size, so no background could show through, and they can only move in character width jumps, right ? So why not use E mode where you can have your multi-colour PMG guys and still smoothly animate other moving objects ? I don't get it.

Probably mostly up to personal preference. It's a lot of fun though, weighing the pros and cons of the different modes on these old computers. Personally I don't mind character based movement in 8-bit games so I think I'd usually prefer more colors instead. Then again when talking about scrolling perhaps smoothnes would be nicer. I'll have a closer look at mode E too to be sure though what would make sense using for my own game.
 

9 minutes ago, R0ger said:

Why mode 4 ? Every color counts, and you use tiles for the map anyway.

You can still move enemies and objects smoothly, with some extra processing. But you have to do the processing in bitmap mode too. You can merge the enemies with background. Again, it's about the same as with bitmap mode. Character mode eats a bit more DMA, and you will most likely need some DLIs (or many), but the extra color is imho worth it.

 

Btw. international karate is in character mode. With shifting and background merging (background being the other character). Games like these will never be 50/60 fps, but you don't really need that. 

 

Thanks for clarifying that, it really makes sense. I was also already wondering about that if you want to have pixel-smooth movement, you probably have to do some similar movement processing in bitmap mode as in character mode.
 

Edited October 16, 2019 by Turbo Laser Lynx

[Alfred]

2 minutes ago, R0ger said:

Btw. international karate is in character mode. With shifting and background merging (background being the other character). Games like these will never be 50/60 fps, but you don't really need that.

Sure and it works there because the background where they are is a solid colour. Bruce Lee as an example has a character-based background, but I don't see how you could animate Bruce, Yamo and the Ninja with character tiles and have smooth animation, You'd need a boat load of characters for each player to match the backgrounds they are jumping around, I don't think you'd have enough memory to do that and have smooth movement.

 

It just seems to me that E mode gets disparaged a great deal, when I think it really has a place for many game types. Antic 4 doesn't strike me as being this super amazing mode, just because you can get a fifth colour. Being character-based, it seems to me to have a lot of limitations of its own.

[NRV]

26 minutes ago, Alfred said:

Sure and it works there because the background where they are is a solid colour. Bruce Lee as an example has a character-based background, but I don't see how you could animate Bruce, Yamo and the Ninja with character tiles and have smooth animation, You'd need a boat load of characters for each player to match the backgrounds they are jumping around, I don't think you'd have enough memory to do that and have smooth movement.

Nope, that's not how you do it.

You can have smooth animation and movement of your software sprites, in a char based mode, over a detailed and scrolling background (if you want), without requiring a lot of memory.

And in some cases it could be faster than doing the same in bitmap mode.. but that analysis would be for a long post x)

 

You don't need to have every combination of a sprite and background in memory (well.. if you have the memory, then that would be faster :)).

What you do is to reserve some some chars in the font for your sprite, and when you want to draw it to the screen, you put those chars over the background.

THEN you write the same background info that was there before, INTO the memory in the font, for those chars.

After that you write the sprite data over that same font memory, using proper masking (and, ora instructions).

 

There is some extra details, but that's the general idea..

 

Edited October 16, 2019 by NRV

[rensoup]

31 minutes ago, Alfred said:

Sure and it works there because the background where they are is a solid colour. Bruce Lee as an example has a character-based background, but I don't see how you could animate Bruce, Yamo and the Ninja with character tiles and have smooth animation, You'd need a boat load of characters for each player to match the backgrounds they are jumping around, I don't think you'd have enough memory to do that and have smooth movement.

 

It just seems to me that E mode gets disparaged a great deal, when I think it really has a place for many game types. Antic 4 doesn't strike me as being this super amazing mode, just because you can get a fifth colour. Being character-based, it seems to me to have a lot of limitations of its own.

ModeE's the fastest mode as far as I'm concerned... If you need the best performance and you're ok spending some memory for it, it's probably the most suitable mode

 

Mode4 still allows for smooth movement though, you just need to keep some chars aside for masking the sprites and background in realtime, like modeE just less easy and slower (You seem to assume that every combination of sprite and background has to be precomputed which is not the case)

(just like NRV said a minute before me!)

 

For this game though, Mode4 seems good enough.

Edited October 16, 2019 by rensoup

[R0ger]

Some game are also only possible in character mode, like this project of mine: https://atariage.com/forums/topic/284327-puyo-puyo-wip/

Here is video: https://www.youtube.com/watch?v=VAXHc5DWb0M

 

First there are tons of movement. When the stacks collapse, it's one character per frame speed. Impossible in bitmap mode.

Second there are 'tiles' which the playfield consist off, so the character mode is logical.

Third .. character mode and PMG give me those extra colors. 6 is so much more than 4.

And last - watch the black puyos .. time to time they all shrink at the same time. It's to distinguish them more from the rest .. and it's very simple to do in character mode, even if I have 4 character sets. Even platformers use this 'repeated animation' often.

 

I'd say for a platformer, or puzzle game like Puyo, I don't see any advantage in bitmap mode at all.

 

 

 

[Alfred]

47 minutes ago, NRV said:

You don't need to have every combination of a sprite and background in memory (well.. if you have the memory, then that would be faster :)).

What you do is to reserve some some chars in the font for your sprite, and when you want to draw it to the screen, you put those chars over the background.

THEN you write the same background info that was there before, INTO the memory in the font, for those chars.

After that you write the sprite data over that same font memory, using proper masking (and, ora instructions).

 

There is some extra details, but that's the general idea..

 

Ok, that makes sense. I figured I had to be missing something, that there was a reason it gets used so much.

[Alfred]

3 minutes ago, R0ger said:

Some game are also only possible in character mode, like this project of mine: https://atariage.com/forums/topic/284327-puyo-puyo-wip/

Here is video: https://www.youtube.com/watch?v=VAXHc5DWb0M

 

I'd say for a platformer, or puzzle game like Puyo, I don't see any advantage in bitmap mode at all.

 

 

 

Yes, for that game character mode makes perfect sense.

[rensoup]

3 hours ago, R0ger said:

I'd say for a platformer, or puzzle game like Puyo, I don't see any advantage in bitmap mode at all.

I meant in general of course, puzzle games are an exception... platformers hmm... I dont know... I wouldn't attempt to port a game like Bubble Bobble in character mode (even in bitmap mode it would be tricky)

[R0ger]

11 hours ago, rensoup said:

I meant in general of course, puzzle games are an exception... platformers hmm... I dont know... I wouldn't attempt to port a game like Bubble Bobble in character mode (even in bitmap mode it would be tricky)

That's good argument for bitmap mode ! I mean 2D movement. Character mode is good for movement in one direction. Horizontal only is the best. You only need 1 extra character on each row as buffer. IK works like that. Also in many platformers, enemies only move in one direction, and often even only in horizontal.

Vertical only also only needs one extra character per every column. But you are likely to cross DLI lines, with possible charset change, and you have to have slightly more complex logic. Nothing impossible though.

2D movement of sprite requires extra character in both direction. So 2x2 sprite requires 3x3 characters, AND you can cross DLI lines. The sprite processing is more complex. And if sprites can move freely, it will be harder to use the extra color. You can only do that on places where no SW sprite can go over it.

 

[emkay]

16 hours ago, Alfred said:

It's only funny if I knew what you were talking about. I'm assuming the larger image with the two characters is the C64 and the purple thing is the Atari, since you said the image with the two characters had never been done on the Atari.

 

It is of course an Image "done" on the Atari. There is just no game using that method.

 

16 hours ago, Alfred said:

 

 

 

As for the rest, I really have no idea what you're on about. I find it hard to believe that you can have a scrolling background with characters and have character-based players in the foreground.

 

 

The Background is PMg .

 

16 hours ago, Alfred said:

 

You would need dozens if not hundreds of copies of the player characters to match the background character that was behind them every frame, I imagine you'd run out of memory.

 

No, you just set the x position of every player to scroll the background. The two guys were build on characters.

 

Funny additional fact ? You could add several scrolling layers with a very low CPU usage.  

 

16 hours ago, Alfred said:

The image looks nice, but I still don't see how you can animate your player character horizontally say, a pixel width at a time without needing a huge number of characters. E mode allows this, it just swaps space for time, but time is (almost) unlimited, space is not.

Mode E is the death of all speed on the Atari.

[emkay]

 

Here is some update:

 

 

As you might see, it is working in ALTIRRA

 

This time I added some Door. As there are about 16 Characters free, something like a "Door" could be set to the Front. The boundaries are given by the character graphics. The guys will stay "behind the door" without any calculation for masking. Scrolling the background (PMg) slower than the "Door" would be no problem. If the guys get handled interleaved, they could be updated without double buffering. 

In fact, as there is no comparable solution available, it is about "fine tuning" , how far colors and details can be added. It's also depending on the engine, how many DLIs could be added to not interfere the speed of the projection of the two guys.    

 

[emkay]

Thinking about it, a Torii might fit better to a Dojo