Weird effect when scrolling

AndyJF · 20 October 2021, 15:56

I'm trying scrolling effects for the first time but getting a strange ripple / flicker. You can see it here

[ Show youtube player ]

In each program loop, I use screen copy to move the whole screen down by 1 pixel then paste what was the bottom line of pixels back at the top, but as you can see it's not a smooth effect. I've tried using Def Scroll but it's exactly the same. I am using double buffer.

Thanks

Setup - WinUAE 4.4.0, Windows 10, AMOS Pro V2

rothers · 20 October 2021, 17:07

Do you have a waitvbl?

I have a vague memory of a plugin for amos which gave far faster scrolling blits for this function.

AndyJF · 20 October 2021, 18:25

Yeah I've got a wait vbl

Retro1234 · 20 October 2021, 20:14

Probably too bigger area for screen copy, screen copy was a terrible way to scroll a screen use hardware scrolling with the Screen Offset command.

AndyJF · 21 October 2021, 10:59

Screen offset works perfectly, thanks!

[ Show youtube player ]

Retro1234 · 21 October 2021, 17:36

Looks like your vertical scrolling tiles.
Idrougge kindly shared some code to endlessly hardware scroll vertically with tiles in Amos, it might be useful

http://eab.abime.net/showthread.php?t=80646

AndyJF · 22 October 2021, 08:56

Thanks for the link, I'll take a look

rothers · 22 October 2021, 11:27

Amos not including a built-in solution to scrolling was a disaster.

Retro1234 · 22 October 2021, 17:49

it does Screen Offset ?

rothers · 22 October 2021, 18:29

Quote:

Originally Posted by Retro1234

it does Screen Offset ?

It has no (tile) scrolling engine though.

So it's a fiasco to figure out the best way to do it.

If you go about it wrong it's hopelessly slow (but the manual gives no indication of the right/most optimised route).

I still could not tell you the fastest way to do it in AMOS.

You just end up with games using the max screen size and hacks.

Retro1234 · 22 October 2021, 18:34

Same as every Amiga language but what still baffles me is examples back in the day, like with Tome telling people to use screen copy for scrolling, we know now this wrong but why they endorsed this? anyone have any idea?

20 October 2021, 15:56	#1
AndyJF Registered User Join Date: Sep 2021 Location: Leeds, UK Age: 54 Posts: 13	Weird effect when scrolling I'm trying scrolling effects for the first time but getting a strange ripple / flicker. You can see it here [ Show youtube player ] In each program loop, I use screen copy to move the whole screen down by 1 pixel then paste what was the bottom line of pixels back at the top, but as you can see it's not a smooth effect. I've tried using Def Scroll but it's exactly the same. I am using double buffer. Thanks Setup - WinUAE 4.4.0, Windows 10, AMOS Pro V2

21 October 2021, 17:36	#6
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	Looks like your vertical scrolling tiles. Idrougge kindly shared some code to endlessly hardware scroll vertically with tiles in Amos, it might be useful http://eab.abime.net/showthread.php?t=80646 Last edited by Retro1234; 22 October 2021 at 08:43.

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20 October 2021, 17:07	#2
rothers Registered User Join Date: Apr 2018 Location: UK Posts: 487	Do you have a waitvbl? I have a vague memory of a plugin for amos which gave far faster scrolling blits for this function.

20 October 2021, 18:25	#3
AndyJF Registered User Join Date: Sep 2021 Location: Leeds, UK Age: 54 Posts: 13	Yeah I've got a wait vbl

20 October 2021, 20:14	#4
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	Probably too bigger area for screen copy, screen copy was a terrible way to scroll a screen use hardware scrolling with the Screen Offset command.

21 October 2021, 10:59	#5
AndyJF Registered User Join Date: Sep 2021 Location: Leeds, UK Age: 54 Posts: 13	Screen offset works perfectly, thanks! [ Show youtube player ]

22 October 2021, 08:56	#7
AndyJF Registered User Join Date: Sep 2021 Location: Leeds, UK Age: 54 Posts: 13	Thanks for the link, I'll take a look

22 October 2021, 11:27	#8
rothers Registered User Join Date: Apr 2018 Location: UK Posts: 487	Amos not including a built-in solution to scrolling was a disaster.

22 October 2021, 17:49	#9
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	it does Screen Offset ?

22 October 2021, 18:34	#11
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	Same as every Amiga language but what still baffles me is examples back in the day, like with Tome telling people to use screen copy for scrolling, we know now this wrong but why they endorsed this? anyone have any idea?

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