Update 42 - New graphics mode

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robpearmain
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Update 42 - New graphics mode

Post by robpearmain » Tue Jan 22, 2019 10:16 pm

Update 42 says

“Documentation about these will appear by Sunday 20/01/2019 on SpecNext.com.”

Please can you provide the link?
Rob Pearmain
Bipboi (Zx Spectrum 48k), Harry Hedgehog (ZX Spectrum [1K]), Luna C (PC), Turbotoons (PC)

ZX Spectrum 48k, +, 128k, Next (board)

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varmfskii
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Re: Update 42 - New graphics mode

Post by varmfskii » Tue Jan 22, 2019 10:31 pm

my guess is we're all going to have to be a bit more patient for that info.
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Ped7g
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Re: Update 42 - New graphics mode

Post by Ped7g » Tue Jan 22, 2019 10:56 pm

It's Sunday 20.1. in programmers time, i.e. probably next tuesday.. :) (or sooner but with bugs and deficiencies... :D )

Alcoholics Anonymous
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Re: Update 42 - New graphics mode

Post by Alcoholics Anonymous » Wed Jan 23, 2019 7:25 am

It was just finalized today so maybe a short wait for running tests and writing documentation.

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sol_hsa
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Re: Update 42 - New graphics mode

Post by sol_hsa » Wed Jan 23, 2019 11:22 am

is it a 128x128 truecolor mode? =)

JoeZX
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Re: Update 42 - New graphics mode

Post by JoeZX » Wed Jan 23, 2019 1:07 pm

normal communication, lively enthusiastic forum, nov. 2018, dev team: we are working .. trying .. whatever .. on new gfx mode 320x224px, tiled based, 5 bits color per pix, framebuffer 45KB .. random numbers - I am not a coder nor expert of comp architecture. In later weeks/months we are all following progress in realtime /tidbits and shit/ whether it succeeds or fails. Same with new sprite engine, color mixing, priority L2 colour functions etc.

autistic approach - zero communication, no life left, dead forum.

thanks.

Alcoholics Anonymous
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Re: Update 42 - New graphics mode

Post by Alcoholics Anonymous » Wed Jan 23, 2019 2:55 pm

sol_hsa wrote:
Wed Jan 23, 2019 11:22 am
is it a 128x128 truecolor mode? =)
There's already a 128x96 9-bit colour mode (called lores) so probably not.
True colour must be the smiley bit :D

Ped7g
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Re: Update 42 - New graphics mode

Post by Ped7g » Wed Jan 23, 2019 3:18 pm

Alcoholics Anonymous wrote:
Wed Jan 23, 2019 7:25 am
It was just finalized today so maybe a short wait for running tests and writing documentation.
Actually, that mode could have remained secret for as many days as you need, but you could have at least updated the other docs maybe...

Then again, I guess I have most of it already in wiki and hopefully correctly, if the new mode is the only addition. So for me personally the new version of docs is interesting only as cross-check to validate wiki, and to give Cesar "this is now official" nudge to fix ZEsarUX more... ;)
sol_hsa wrote:
Wed Jan 23, 2019 11:22 am
is it a 128x128 truecolor mode? =)
The DAC converting current into video signal is capable only of 8 levels, so RGB 3:3:3 is maximum possible colour space (unless you would go the dark route of banging on the DAC in weird ways to make it drop more levels, like demo "8088 MPH" ( https://youtu.be/yHXx3orN35Y ) does with original IBM PC with CGA card, but that's not very practical, and only few humans will ever write code like that... (BTW, it's "1981" HW, so technically NEXT is like 5-6 years better... yet replicating that demo on Next would be not completely trivial)

So unless you want to modify certain parts of the board, the 9 bit palette is fixed, don't expect more in some meaningful way. With 120Hz/144Hz LCDs it would be interesting to get 120/144Hz mode and try to change colours each frame, with current LCD ghosting and response time, on some displays it would be maybe possible to produce larger colour space in predictable way... but this is brutally far fetched either, as 120/144Hz modes are very far away from current modes, so they would probably need complete rethink of core, and how to make those related to ZX in some way, and each LCD has it's own ways of overdrive & postprocessing, so this is more like telling you joke, than serious thing.

IMO the most benefit to SW devs on ZX would be either 512x384 hi-res mode (like Timex, but also double-lines) - for better texts mostly, this would help tremendously with adventure-like games and similar, and any decent tile-mode to make arcade 2D games simpler to write and perform better... Although if you are seasoned ZX dev, the lack of ULA-like tile mode is not a problem. Layer2 being tiled, that would be something completely different, as currently Layer2 is near unusable with anything what requires "redraw" of larger area.. with tiles that would open path for many tricks, making Layer2 useful even for SW which needs to update large part of screen (but can base it's graphic on tiles).

Alcoholics Anonymous
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Re: Update 42 - New graphics mode

Post by Alcoholics Anonymous » Wed Jan 23, 2019 4:38 pm

Ped7g wrote:
Wed Jan 23, 2019 3:18 pm
IMO the most benefit to SW devs on ZX would be either 512x384 hi-res mode (like Timex, but also double-lines)
Right now the video generation only creates 240 visible pixel rows vertically for HDMI (and a bit bigger for VGA). The sprite surface is 320x256 so in fact the top 8 pixel rows and the bottom 8 pixel rows are not visible on HDMI, although all of it can be seen with a thin top and bottom border in VGA. The new video mode occupies the same area on screen and again the top and bottom 8 pixel rows can't be seen on HDMI. This is rather more relevant for the new video mode and should be kept in mind when using it.
as currently Layer2 is near unusable with anything what requires "redraw" of larger area..
You have something around an 11-12 MHz cpu to write to layer 2 including the slowdown. On an original spectrum there were about 70000 cycles to write the display at 3.5MHz in one 50 Hz frame, or about 10.1 cycles per screen byte per frame and this figure does not include contention. Layer 2 gives you about 230000 cycles in the same time or about 4.7 cycles per screen byte per frame. So it is underpowered compared to the original spectrum on its display. But it's not quite equivalent as the hardware has dma to speed copies, hardware scrolling and some special instructions for layer 2 which I think should make up for a lot of the difference.

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sol_hsa
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Re: Update 42 - New graphics mode

Post by sol_hsa » Wed Jan 23, 2019 5:23 pm

I threw it as a joke, but since we're talking, it should be relatively trivial to do hardware dithering with animated pattern, but that would only yield 1-2 bits of more depth..

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