The gigascreen thread!

[5MinuteRetro]

So, until the Super Mario Brothers thread, I'd not before heard of gigascreen. Or if I had, I'd forgotten about it. I'm gobsmacked by how good it looks on my ZXDS.

What other gigascreen games/demos do I need to download TODAY?!

[5MinuteRetro]

First on the list, courtesy of Ast A. Moore is Nether Earth, which has a subtle gigascreen effect applied to the radar, at the bottom, to create a kind of (to my eyes) light green/olive shade...

[djnzx48]

Gyron (1985) is the earliest game I know of to utilise gigascreen, for the map in the corner and the rotating polyhedron. Vradark's Sphere used a similar effect for its map.

As for demos, there are many that use gigascreen; Mescaline Synesthesia is one notable example.

[stupidget]

Having read about 'Gigascreen' for the first time on the Super Marion thread, could somebody please explain what it is? Is is for smoother scrolling or something to do with colour?

[Ast A. Moore]

Another game that uses gigascreen effects is Soldier of Fortune. (There’s also a link to my bug fix for the game a couple of posts later in that thread.) The effect is more apparent. It’s used for some in-game text that appears on the screen during gameplay and for quite a few objects you interact with.

[Ersh]

Having read about 'Gigascreen' for the first time on the Super Marion thread, could somebody please explain what it is? Is is for smoother scrolling or something to do with colour?

On every frame you basically alternate between two screens. The colours will "blend" creating faux colours. Like if you have red on one screen, blue on the other, then you will perceive something purple.Though the further the two colours' brightness are from each other the more it'll appear to flicker. A higher refresh rate will reduce the flicker, but the PAL Spectrum is of course stuck at 50hz.

[5MinuteRetro]

Gyron (1985) is the earliest game I know of to utilise gigascreen, for the map in the corner and the rotating polyhedron. Vradark's Sphere used a similar effect for its map.

Just checked Gyron. The effect is evident on the map, but truly awful -- very, very flickery (on my DS, anyway). Don't see it applied to the polyhedron, but perhaps I'm looking at the wrong thing.

[5MinuteRetro]

Another game that uses gigascreen effects is Soldier of Fortune. (There’s also a link to my bug fix for the game a couple of posts later in that thread.) The effect is more apparent. It’s used for some in-game text that appears on the screen during gameplay and for quite a few objects you interact with.

So it does! Yeah, the effect is obvious. Also quite flickery, though -- at least on my DS. The gigascreen effects in Super Mario Brothers are way more convincing, for whatever reason.

[stupidget]

Having read about 'Gigascreen' for the first time on the Super Marion thread, could somebody please explain what it is? Is is for smoother scrolling or something to do with colour?

On every frame you basically alternate between two screens. The colours will "blend" creating faux colours. Like if you have red on one screen, blue on the other, then you will perceive something purple.Though the further the two colours' brightness are from each other the more it'll appear to flicker. A higher refresh rate will reduce the flicker, but the PAL Spectrum is of course stuck at 50hz.

So when I run the TAP of Super Mario on my original +2 plugged into a new flatscreen TV will I not get the desired gigascreen effect? Reason I ask is that all i see are reds, greens and cyans and nothing I wouldn't expect from a normal speccy game.

[5MinuteRetro]

So when I run the TAP of Super Mario on my original +2 plugged into a new flatscreen TV will I not get the desired gigascreen effect? Reason I ask is that all i see are reds, greens and cyans and nothing I wouldn't expect from a nor al speccy game.

I can't answer that, per se, because I don't know the technical ins and outs. But what I can say is focus on Mario -- particularly large Mario -- when he's standing still. His arms and body (and hat and feet) are stippled, which I think is a simple case of two versions of Mario being rapidly refreshed. But the effect of those offset pixels being on then off is that these areas appear as a (near-)solid grey that the Spectrum cannot normally produce. I think that effect is also dependent on persistence of vision so much as anything else, so I'm guessing people will sometimes see it differently, even on the same display.

Btw, I just grabbed this shot from my DS running SMB on ZXDS. You can clearly see the stippling, but to the naked eye (or my naked eye), and on the DS screen, this is a virtually-solid grey. See also the red platform at the bottom. Here it's clearly stippled, but on the DS screen it looks like a more subdued (or at least different) solid red than the Spectrum's only real solid red (be that BRIGHT 1 or BRIGHT 0 red).

(Click the image to see the full-size version)

[stupidget]

Yeah i don't get any of that. Even in that image I can see the flooring is more of a brown than the Speccy Red that I get on my +2.

[Ersh]

So when I run the TAP of Super Mario on my original +2 plugged into a new flatscreen TV will I not get the desired gigascreen effect? Reason I ask is that all i see are reds, greens and cyans and nothing I wouldn't expect from a normal speccy game.

You'll get the effect if you run it on real hardware, like 5min said it's a persistence of vision thing. I've read that there is a hardware mod for Pentagon machines that will blend the frames and output them as one, this would remove all perceived flicker.

[stupidget]

So when I run the TAP of Super Mario on my original +2 plugged into a new flatscreen TV will I not get the desired gigascreen effect? Reason I ask is that all i see are reds, greens and cyans and nothing I wouldn't expect from a normal speccy game.

You'll get the effect if you run it on real hardware, like 5min said it's a persistence of vision thing. I've read that there is a hardware mod for Pentagon machines that will blend the frames and output them as one, this would remove all perceived flicker.

But I think because my +2 is plugged into a modern TV and not a CRT then the effect isn't working.

[Ersh]

But I think because my +2 is plugged into a modern TV and not a CRT then the effect isn't working.

It should work regardless, it's still refreshing the screen at 50hz.

The ground in SMB is mixing red with black and should produce a darker red, not brown. I think that photo may contain some artifacts.

When you look at Mario clothes, aren't they grey-ish? Or do you simply see the checkerboard pattern?

[stupidget]

Mario's clothes are checkerboard and the colours are just normal speccy colours.

[Ersh]

All colour blending in the game seems to be with black as one colour so don't focus on seeing 'new' colours here. They'll all just be a darker version of their original colour. You should be able to see Mario in 3 colours though, black,white and a grey. If you're just seeing the checkerboard pattern, I've got no idea mate.

[Alessandro]

So, until the Super Mario Brothers thread, I'd not before heard of gigascreen.

And it was all my fault...

[Guesser]

It will depend on what deinterlacing algorithm your TV uses, and how it interprets the spectrum's video signal.

[djnzx48]

Gyron (1985) is the earliest game I know of to utilise gigascreen, for the map in the corner and the rotating polyhedron. Vradark's Sphere used a similar effect for its map.

Just checked Gyron. The effect is evident on the map, but truly awful -- very, very flickery (on my DS, anyway). Don't see it applied to the polyhedron, but perhaps I'm looking at the wrong thing.

The polyhedron effect is visible in the RZX demo of Gyron Atrium, at the beginning anyway.

One of the reasons these uses of the effect doesn't look so good is that they're flickering entire sections of the screen on and off. Modern demos usually interleave the two screens together using rapid screen switching, so the flicker is only applied to small screen sections and it's not so noticeable.

[djnzx48]

So when I run the TAP of Super Mario on my original +2 plugged into a new flatscreen TV will I not get the desired gigascreen effect? Reason I ask is that all i see are reds, greens and cyans and nothing I wouldn't expect from a normal speccy game.

You'll get the effect if you run it on real hardware, like 5min said it's a persistence of vision thing. I've read that there is a hardware mod for Pentagon machines that will blend the frames and output them as one, this would remove all perceived flicker.

Do you know any details about such a hardware mod? I've heard many rumours about this but I can't find any actual examples of mods that can do frame blending.

[DenisGrachev]

So, until the Super Mario Brothers thread, I'd not before heard of gigascreen. Or if I had, I'd forgotten about it. I'm gobsmacked by how good it looks on my ZXDS.

What other gigascreen games/demos do I need to download TODAY?!

Maybe it's time to heard about MultiGigaScreen - it's a combination of multicolor and gigascreen, or even about interlaced multigigascreen as a most powerfull speccy mode?

Btw, my game Twinglight https://spectrumcomputing.co.uk/index.p ... 6&id=31994 use a sort of uninterlaced multigigascreen, a combination of multicolor 8x4 and gigascreen to produce more colors.

There is a several problems with that tech and modern tvs. Gigascreen was widely use in exUSSR demoscene in 90-s just because most coders have a monitors\tvs that displays it with a very small flicker. That's why we still have a pure gigacreen flicked demos like:

https://youtu.be/OVLR4fGM2n8

At modern lcd tvs we have another problem when gigacreen works speccy switches in "LCD MODE" that doubles vertical resolution, so you gigscreen will be displayed not correctly and interlaced gigacreen too. So, that's why i prefer a ZX Evolution that supports even a English classic speccys timing but have a proper VGA scandabler that show a proper picture on LCD monitors even with gigascreen and interlaced one.

[moroz1999]

Some images from ZX-Art:

Gigascreen:
https://zxart.ee/eng/graphics/database/ ... e:flicker/
https://zxart.ee/eng/graphics/database/ ... e:flicker/

Gigascreen with multicolor 8*4:
https://zxart.ee/eng/graphics/database/ ... e:flicker/

Gigascreen with multicolor 8*2:
https://zxart.ee/eng/graphics/database/ ... e:flicker/

Gigascreen with multicolor 8*1:
https://zxart.ee/eng/graphics/database/ ... e:flicker/

[4thRock]

At modern lcd tvs we have another problem when gigacreen works speccy switches in "LCD MODE" that doubles vertical resolution, so you gigscreen will be displayed not correctly and interlaced gigacreen too.

Since 288p50 (Spectrum output) is not a standard SD resolution, the TV defaults to the closest valid mode: 576i50
Just like the Amiga interlace modes, this is like running the Spectrum with twice the vertical lines (256x384 active area).
In theory, if you used this effect with the Timex modes, you could get 512x384 with 4 colours...

(I'm no coder, but the Timex changed screen modes by sending data to the border address (OUT 255,62). Perhaps programmers could agree on similar signaling for other modes, that would tell emulators and real hardware what mode to display).

[stupidget]

This is what I get:

[media]https://youtu.be/7f4p45htPGc[/media]

[Ast A. Moore]

This is what I get:

Playing Spectrum games at a 16:9 ratio?