Uneven scanlines if an overlay is selected

Retro-Nerd · 14 April 2018, 01:07

This is some older issue i guess. All shaders have some kind of uneven scanlines when you use an overlay. Looks like this:

Darker scanlines (and combining with a mask) is even worse.

I talked with guest.r and he said that it's caused due to a non-integer prescale. So, my question: Can you add an integer prescaling to WinUAE?

btw: it happens without an overlay image too. Harder to spot but it's surely there. Annoys a bit in vertical scrolling.

Toni Wilen · 14 April 2018, 09:14

Config file required + overlay files.

Retro-Nerd · 14 April 2018, 14:13

Sure.

https://www.sendspace.com/file/kb8lv4

Toni Wilen · 14 April 2018, 16:27

Right, overlay adds extra scaling (to match transparent area) which causes shader scaling mismatch..

Not sure how to fix this properly..

Retro-Nerd · 14 April 2018, 16:50

Yeah, thought so. Tried to cut the top/bottom of the overlay a bit to have more vertical resolution. But it wasn't enough. Maybe a scaling option for the overlay itself could help? In RetroArch it looks fine.

Toni Wilen · 14 April 2018, 17:46

Correct fix is to make overlay area final output size, not using configured windowed/fullscreen size which is then scaled to overlay size..

Not yet sure if this is easy or not that easy..

Foebane · 14 April 2018, 20:42

I deleted my previous post because it was deemed unhelpful, but I was trying to point out that a scaling mismatch would manifest itself in the pictures you provided, Retro-Nerd. I know exactly what the problem is: if there is a mismatch in resolution (x and y) between your overlay and the screen resolution, then the banding patterns in your screenshots will occur. They'd have to be exactly the same, or multiples of 2 or 3 or more (integer numbers) to look sharp. It is not easy to fit an Amiga screen resolution this way onto that of a PC, laptop or desktop, invariably the screen area will be clipped at the edges or it will be too small and there will be big black borders.

Retro-Nerd · 14 April 2018, 20:48

Why did you do that? Now my post doesn't even makes sense. Deleted too.

Dunny · 14 April 2018, 20:51

Back when I wrote emulators, we used to just tile the overlay on after scaling and filtering. It didn't look great in all circumstances, but avoided banding.

Foebane · 14 April 2018, 22:31

Quote:

Originally Posted by Retro-Nerd

Why did you do that? Now my post doesn't even makes sense. Deleted too.

I deleted it as my advice didn't involve overlays. I don't even use any on WinUAE.

Retro-Nerd · 10 February 2019, 18:52

Quote:

Originally Posted by Dunny

Back when I wrote emulators, we used to just tile the overlay on after scaling and filtering. It didn't look great in all circumstances, but avoided banding.

@Toni:

Couldn't you just add something inofficial to the ini file for now? So that the PNG is a plain overlay, without the extra scaling inside the PNG frame?

14 April 2018, 01:07	#1
Retro-Nerd Missile Command Champion Join Date: Aug 2005 Location: Germany Age: 52 Posts: 12,444	Uneven scanlines if an overlay is selected This is some older issue i guess. All shaders have some kind of uneven scanlines when you use an overlay. Looks like this: Darker scanlines (and combining with a mask) is even worse. I talked with guest.r and he said that it's caused due to a non-integer prescale. So, my question: Can you add an integer prescaling to WinUAE? btw: it happens without an overlay image too. Harder to spot but it's surely there. Annoys a bit in vertical scrolling. Last edited by Retro-Nerd; 14 April 2018 at 01:36.

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14 April 2018, 09:14	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,515	Config file required + overlay files.

14 April 2018, 14:13	#3
Retro-Nerd Missile Command Champion Join Date: Aug 2005 Location: Germany Age: 52 Posts: 12,444	Sure. https://www.sendspace.com/file/kb8lv4

14 April 2018, 16:27	#4
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,515	Right, overlay adds extra scaling (to match transparent area) which causes shader scaling mismatch.. Not sure how to fix this properly..

14 April 2018, 16:50	#5
Retro-Nerd Missile Command Champion Join Date: Aug 2005 Location: Germany Age: 52 Posts: 12,444	Yeah, thought so. Tried to cut the top/bottom of the overlay a bit to have more vertical resolution. But it wasn't enough. Maybe a scaling option for the overlay itself could help? In RetroArch it looks fine.

14 April 2018, 17:46	#6
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,515	Correct fix is to make overlay area final output size, not using configured windowed/fullscreen size which is then scaled to overlay size.. Not yet sure if this is easy or not that easy..

14 April 2018, 20:42	#7
Foebane Banned Join Date: Sep 2011 Location: Cardiff, UK Age: 51 Posts: 2,871	I deleted my previous post because it was deemed unhelpful, but I was trying to point out that a scaling mismatch would manifest itself in the pictures you provided, Retro-Nerd. I know exactly what the problem is: if there is a mismatch in resolution (x and y) between your overlay and the screen resolution, then the banding patterns in your screenshots will occur. They'd have to be exactly the same, or multiples of 2 or 3 or more (integer numbers) to look sharp. It is not easy to fit an Amiga screen resolution this way onto that of a PC, laptop or desktop, invariably the screen area will be clipped at the edges or it will be too small and there will be big black borders.

14 April 2018, 20:48	#8
Retro-Nerd Missile Command Champion Join Date: Aug 2005 Location: Germany Age: 52 Posts: 12,444	Why did you do that? Now my post doesn't even makes sense. Deleted too.

14 April 2018, 20:51	#9
Dunny Registered User Join Date: Aug 2006 Location: Scunthorpe/United Kingdom Posts: 1,989	Back when I wrote emulators, we used to just tile the overlay on after scaling and filtering. It didn't look great in all circumstances, but avoided banding.

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