Dual Layer Graphics example + source

[roondar]

Ever since making the Free Form Sprite Layer example a few years ago, I've been wanting to have another go at creating a dual layer screen on my A500 without using Dual Playfield mode. I eventually ended up with two ideas floating around in my head and decided that the best way to deal with these ideas was to turn them into my next video/article.

For comparison, I also added the standard repeating pattern Sprite background as used in several games. All in all, I ended up with an example program that shows three different ways of creating a dual layer screen.

As always, I've included the full source code and a download of the program itself on my website. Note that my example uses the startup code by Photon of Scoopex, a random number generator I found on EAB, written by Meynaf and uses tiles ripped from Turrican II. It requires at least 1MB of RAM (of which 512KB Chip RAM*).

The article & source can be found here:
https://powerprograms.nl/amiga/dual-layer.html

Here's the YouTube video:
[ Show youtube player ]

*) the example uses a lot of Chip Memory because everything for all three variants is kept in memory all the time. It needs at least 420KB of free Chip RAM to run.

[vulture]

Very nice and very informative, thx roondar!

[ross]

Very good article, as usual.
In particular the part about the dual layer with blitter in single playfield mode, which is not documented so precisely and exhaustively anywhere else.

[roondar]

Originally Posted by vulture

Very nice and very informative, thx roondar!

Thanks

Originally Posted by ross

Very good article, as usual.
In particular the part about the dual layer with blitter in single playfield mode, which is not documented so precisely and exhaustively anywhere else.

Thanks, it was a lot of fun to fiddle around with the Blitter and the palette settings. I had been wanting to one of these for aaaaages, but real life kept getting in the way.
I'm especially happy it managed to perform roughly identical to a simple Sprite layer

[Jobbo]

Really nice work!

It must take a ton of effort to make those videos and the write ups, even compared to how much time it takes to make the code.

Love hearing about these sorts of experiments in great detail, much appreciated!

[roondar]

Originally Posted by Jobbo

Really nice work!

It must take a ton of effort to make those videos and the write ups, even compared to how much time it takes to make the code.

Love hearing about these sorts of experiments in great detail, much appreciated!

Thanks!

Yes, the work on the article and video is "non-trivial"
I don't have an exact split, but it feels to me like it's a roughly 50/50 split between the code and the article/video.

[alkis]

Very nice work, thank you.
Liked and subscribed of course.

[robinsonb5]

Very nice - I really like the tabbed presentation on the webpage, too.

[paraj]

Very nice article! :
One small comment about the page is that the fixed margins makes it very hard to read on a small screen (e.g. phone).

[roondar]

Originally Posted by paraj

Very nice article! :
One small comment about the page is that the fixed margins makes it very hard to read on a small screen (e.g. phone).

I'll have to take a look at that. It didn't use to do that, it used to size alongside the display side (i.e. no margins on phones). Thanks for pointing it out!

Edit: should be fixed now, though you may have to force a browser cache clear on your phone first before it'll sort itself out.

[buzzybee]

Great feature, thank you for putting that together and sharing it. May I add that my games from the "Reshoot" series use the "fake" Dual Playfield mode that you mention, based on the benefits of AGA-chipset.

With the 256 color registers of the AGA-chipset, you may set up two playfields with 15 individual colors each; or two playfields with 15/7 individual colors. That way, sufficient color regs remain to set up sprite colors of your choice. Feels very desirable for a shoot-em-up game.

On AGA the color glitches mentioned in your video may be turned into a fake 3 or 4-bit alpha channel, thus providing the illusion of transparency. That is if the palette is chosen wisely.

[paraj]

Originally Posted by roondar

I'll have to take a look at that. It didn't use to do that, it used to size alongside the display side (i.e. no margins on phones). Thanks for pointing it out!

Edit: should be fixed now, though you may have to force a browser cache clear on your phone first before it'll sort itself out.

Yep, fixed now, and the tabs work much better. Now I can properly enjoy your articles on my morning commute

[roondar]

Originally Posted by buzzybee

Great feature, thank you for putting that together and sharing it. May I add that my games from the "Reshoot" series use the "fake" Dual Playfield mode that you mention, based on the benefits of AGA-chipset.

With the 256 color registers of the AGA-chipset, you may set up two playfields with 15 individual colors each; or two playfields with 15/7 individual colors. That way, sufficient color regs remain to set up sprite colors of your choice. Feels very desirable for a shoot-em-up game.

On AGA the color glitches mentioned in your video may be turned into a fake 3 or 4-bit alpha channel, thus providing the illusion of transparency. That is if the palette is chosen wisely.

That's a very clever way to use the extra bitplanes AGA offers for sure. I especially like those translucent clouds you added to Reshoot III.

[lmimmfn]

Originally Posted by roondar

That's a very clever way to use the extra bitplanes AGA offers for sure. I especially like those translucent clouds you added to Reshoot III.

Also a good for implementing shadows similar to HB mode.

Great video BTW, I really enjoyed that!!!

[ovale]

Thank you for the effort. What tools you used to make the animations in the video?