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-   -   Made a new shader for FS-uae. (http://eab.abime.net/showthread.php?t=104864)

kokoko3k 18 March 2021 09:49


Originally Posted by Photon (Post 1471035)
The only lines I see are vertical, i.e. not what ppl usually mean by scanlines.

There's also some blur and TV mask going on.

Scanlines are actually the pixels, not the space between them. This space is what's left between the glow of the pixel lines above and below the space.

PAL scales perfectly to 1080p by a factor of 4x noninterlaced.

I would love a shader that scales every horizontal Amiga pixel by exactly 4x, leaving 3px room between each scaled line, and then gives control over pixel glow to create the "scanlines". This is a correct shader.

If you look closely on the terrain, you will see that it kinda produces exactly what you say without the need to make a "correct" shader.
This is scanlines.tweaked.shader preset from version 1.35:

Here is a closeup of the terrain:

On the other side, doing what you ask the way you ask, would mean:
* Doubling the gpu use because the glowing code would need to operate on 4 lines for every drawn pixel, on 4K it would mean doing 4X the work.
* losing the compatibility with fs-uae autoscale

That said, my old 1084s was so little compared the the monitor i use today and i wonder why (as you suggest for 1080p) i should think to zoom by a factor of 3 the space between a scanline and the other and not zooming the scanline itself.

The following are shots from my real arcade crt as today:

https://i.ibb.co/frfFBxh/IMG-8777.jpg https://i.ibb.co/WtH8vmv/IMG-8776.jpg https://i.ibb.co/ZLyQP2f/IMG-8775.jpg https://i.ibb.co/yYMkRF7/IMG-8774.jpg https://i.ibb.co/TBMCzJf/IMG-8773.jpg https://i.ibb.co/BzqQyC3/IMG-8772.jpg https://i.ibb.co/pjF3gXN/IMG-8771.jpg https://i.ibb.co/TbPqXK1/IMG-8770.jpg https://i.ibb.co/ScxbBLg/IMG-8769.jpg https://i.ibb.co/TTWC32n/IMG-8768.jpg

dreadnought 18 March 2021 11:43

People usually get fixated on "scanlines", but it's just one of the elements of the CRT image and the drive to make the gaps as thick as possible a totally modern thing. If you think about it, why would anybody want such a disjointed image? It certainly wasn't a thing back in the day. So, shadowmask/aperture grille is equally important, as is colour bleeding and other things, because they make the IQ more uniform.

Also, there is no way you can have one "correct" shader, since there were different types of monitors and TVs. Eg, my Trinitron looks rather different from kokoko3k's arcade monitor, because it's aperture grille vs shadowmask:


RuySan 18 March 2021 14:58

For me the best shader is undoubtedly crt-easymode-halation from Retroarch. Unfortunately the easymode that i downloaded from this thread looks nothing like it.

And I agree that lots of people go crazy for scanlines even though they weren't that prevalent in CRTs. I don't get it. I tried the Royale-Kurozumi shader that's very popular and those scanlines are completely exaggerated and take away much of the image detail.

Retro-Nerd 18 March 2021 17:06

Best Retroarch shader is CRT-Guest-DrVenom/SM, or the newer one Guest is working on called CRT-Guest-Advanced. You can't ask for more.


dreadnought 18 March 2021 17:25

There is no "best" shader, really. It all depends part on personal preference and part on which machine/TV look you want to simulate.

That said, of course Guest is a top notch shader. My favourite is probably Geom, though it all depends on aforementioned factors. Using Geom+Redream (Dreamcast emu) is the first time I've actually said, "hell, this is good enough", and I really am an only-CRT die hard fanatic.

Pyromania 18 March 2021 17:36

This looks great, thanx a bunch.

nobody 18 March 2021 18:53

indeed Crt-easymode-halation on Retroarch looks closer to a real shadow mask CRT, guest.r shader looks stunning too, can be tweaked to look the same.


Photon 21 April 2021 21:02


Originally Posted by kokoko3k (Post 1471088)
doing what you ask [i]the way you ask[/i

will give everyone scanlines on an LCD, finally. This is how a CRT works and looks. You attach images with closeups. This is simply not what we see on a CRT. We don't view it at that distance. This must be understood to understand scanlines.

What I do see in the closeups is 2:2 distance between pixel lines, and horizontal spacing between pixels, preventing the pixels from melting together to pillows as they do on CRTs - viewed with eyes, and not from 5cm distance.

So the recipe is in my original reply. 1080p is perfect, 1:4 distance scanlines, 1px radius blur and done.

If you won't, where are tools and examples shared so I can do it?

kokoko3k 21 April 2021 21:40

Did you at least take a look at the code and the available parameters?
It does not seem so.

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