Can the scrollrect performance issue even be fixed?

So the issue is well known, some Unity devs have stated the performance is a priority. But I am really wondering, can it even be fixed?

If I understand it correctly, using the scroll rects basically causes a regeneration of the UI mesh every tick it scrolls. If that is the case it seems that the scroll rect can never actually become radically preformant. Perhaps some percentage improved with more optimized algorithms, but never perfect. If this is the case then it seems to have a very performant, complex, scroll rect, we must do the multi-canvas trick.

So I am wondering, is something like the multi-canvas trick part of Unity's intended solution to this? Or should I just start rolling my own right now?

 

After going multicanvas (+ no pixel perfect on nested one), and disable all UI layouting related components after rect content is layouted (canvas size fitter, layout groups, layout element) we were able to improve performance of one of our complex lists from ~2fps to ~30fps on lumia 630. Hope this helps.

 

I just wanted to say thanks to Raimis for the notes on performance boosts. I tried disabling the layout group on my panel after populating it and got some minor improvements. I also tried setting items in my list off-screen as inactive, which did a little bit as well, but the massive improvement was turning off pixel perfect for the canvas - the frame rate difference on Windows Phone was huge disabling that (which I guess seems somewhat obvious now). I ended up using 3 different canvases and putting my lists in the one without pixel perfect on to get a great boost in FPS. Thanks much for the tips!

 

That's ok we are all here for the answers and sometimes we do get them. Glad I could've helped.

 

Hi, could you explain or point me to some resources explaining the multi canvas technique ?

I need to make a scroll list made up of other lists that all need to have a vertical layout group, plus I use the layout groups everywhere just to make sure things are presented well.

Everything runs fine in editor, but on the devices, iPhone 6 even has small lags and iPad 3 has very perceptible lags when scrolling.

 

I don't know any written resources. Simply place lists on other canvas than all other UI elements and disable pixel snapping for that canvas. After screen is initialized you can also disable all autolayout components, this was also mentioned above.

 

Do you mean Pixel Perfect check box by pixel snapping ? I already deactivated this.

It seems by deactivating other menus not in use with SetActive and removing some of the layout components, I've been able to get better performance but still not so great on iPad.

The strange thing is on Android (tested on Sony Xperia Ray S18i and Samsung Galaxy Pocket GT-S5310) don't lag so hard even though they are less powerful. Of course they also have a much smaller resolution.

On iPhone 5S it's now flawless.

Also I removed some content size fitters that were children of layout components.

I will now be trying to use the multiple canvas technique instead of SetActive, but as far as I've tried, it seems like the sorting layers in the canvas are different from what's on the camera. I'm not sure how I'm supposed to set this up.

 

Can anybody explain me how to make before-mentioned mulitcanvas trick right? I think I got it working in Unity 4.6, but now I'm using Unity 5.3 and I don't see any performance difference. What I do: ScrollRect's content has it's own canvas, content is one UI Text (TextMeshProGUI to be precise), content's SizeContentFitter is disabled. Still see spikes in profiler when I scroll my text.

 

Thanks for the response, Stephan. Pixel perfect is of course disabled, and as I wrote ContentSizeFitter is disabled after calculations. Profiling shows that Android lags are caused by rebuilding UI batch: PutGeometryJobFence and Canvas.BuildBatch. That's what I want to eliminate by applying multicanvas trick. I just can't find some tutorial about how to do it right.

 

[Canvas Main UI]
[Canvas ScrollRect1]
[Canvas ScrollRect2]

This is how your game objects should look in hierarchy. So when something happens with the ScrollRect1 it only rebuilds the content within [Canvas ScrollRect1]. if you have all your UI within single canvas, when scroll rect is moved it will do exactly what you experience, rebuild every single element every frame just because of scroll rect.

 

@phil-Unity is somebody working on the scrollrect cpp problem?

I'm soon done with my app, which consists almost of scrollrects.
would be sweet if it could stay at 60fps when scrolling.

Unity UI is amazing despite the performance issues with the scrolling.
If someday we could be able to disable the gameloop and use UI only there s no need for xamarin anymore )

 

Hi. Great news.
We've ran into the same issue and developed our own utility that greatly increases performance.
It's 5 bucks on asset store(see the video for comparisons): https://www.assetstore.unity3d.com/en/#!/content/58158

 

"Move" in the sense of actually changing the rect coords, or including the sense of animations, such as button presses? What about changes in visibility?

 

I'm already using this technique .still the fps drop when scrolling and it doesn't feel native.

I've already reported a bug with a sample project. Got confirmed
@thefallengamesstudio well, looks like you re doing the same as enhanced scroller , just for 5 bucks. https://www.assetstore.unity3d.com/en/#!/content/36378

It's a problem the unity team should address.

@phil-Unity bump isn't it?

 

Wow, wish I decided to export this as asset store package when I was working on it during Unity 5 betas Had the same script done myself about 1 year ago

 

@Raimis: cool. how is your framerate? scrolling nice?

 

It improved a lot compared to scrollrect, but we found out that the whole UI mechanism just hates moving parts. If i had to do it now, i guess i'd try to mix ngui with unity gui and that would give the best results.

 

Slows Down?
Do you mean when you have multiple Window panels?

Ex: http://kissui.izzysoft.com/Examples/DragDrop501.html (unity's WebPlayer)

 

I havent used this UI in a while and things might have changed, but back then it used to be that if there's a change in canvas - the whole canvas gets redrawn/recalculated. So having a moving element is essentially slow with this new ui. Once again, I haven't used this UI since ~August, so things might have changed.

 

EDIT 27.08.2016: Hey guys, happy to announce V2.0 is out, improved and with horizontal scrolling support: http://u3d.as/xXQ

Original message:
Yeah, only vertical scrolling is supported, though there may be some very creative ways to simulate a horizontal scrolling from the vertical one, but we were dumb and didn't find one in a reasonable amount of time . If someone finds a way (the easy way, I mean) for faking a horizontal scroll, I'd like to know, so I can update the docs.
Of course, if we'll receive a few more requests for horizontal scrolling, we'll integrate it - the hard way.

 

Canvas.pixelPerfect
Force elements in the canvas to be aligned with pixels. Only applies with renderMode is Screen Space.

Enabling pixelPerfect can make elements appear sharper and prevent blurriness. However, if many elements are scaled or rotated, or use subtle animated position or scaling, it may be advantageous to disable pixelPerfect, since the movement will be smoother without.