Asynchronously getting data from the GPU (DirectX 11 with RenderTexture or ComputeBuffer)

Hi all, just found this thread after a few hours of Googling ways to try and speed up the texture2D.ReadPixels call.

Unfortunately the info in here is way over my head! :/

Can anyone confirm if @Michal_ 's tool can replace the ReadPixels call, and if so, how would RetrieveTextureData be utilised for this case?

Here's the current code I have (in a simple Update() function):

Code (CSharp):

1.  
2.            var rect = new Rect(0, 0, (int)TextureSize.x, (int)TextureSize.y);
3.  
4.             RenderTexture.active = this.renderTexture;
5.  
6.             GL.Clear(false, true, BackgroundColor);
7.  
8.             targetCamera.Render();
9.  
10.             this.texture2D.ReadPixels(rect, 0, 0);          
11.             this.texture2D.Apply();
12.  

Thanks in advance for any help, and apologies if I've misunderstood all of this completely!

 

I'll add "take screenshot" example sometime next week if I have time.

 

Hi tntfoz, this is possible with the native plugin by Michal_. If you want to take only one screenshot once in a while the unity-example in github should be good.

However if you would like to capture frames in a higher fps-count, using multiple textures seems necessary, because the texture will need some time to be ready to read. But it seems that the textures are not necessarily received in the order that you actually requested it (at least that's the case in my scene until now).

Coming back to your question: Capturing a single screenshot seems to be working. Capturing a video-like raw image sequence seems not to work (or I haven't figured out how)

 

Thank you both!

 

@tntfoz sorry, I still don't have time. Too much work. But I still plan to do it one day.

 

No problem! Thanks @Michal_

 

Hey @Michal_ Ive been testing out your plugin which is extremely useful for what I'm working on.
Unfortunately its also causing unity crashes. I'm probably doing something wrong but i'm really not sure how to debug it correctly.

 

There's probably a bug in the plugin if it crashes unity. Or a bug in unity. Probably the plugin though. Can you make a small repro project? I won't have much time in the next few weeks but I will take a look eventually...

 

Hi Michal_,

do you know if Unity did in any way consider add your plugin to the native repository / Unity code or at least implement a similar feature themselfs?

That plugin is so usefull and it is such a pain that Unity3D has such a big functional gap when it comes to the GPU->CPU communication, I really wonder why they don't pick that topic up??

 

I have no such information. I even asked unity guys how exactly native plugin callbacks work internally so that I could make this more efficient but I never got any response.

Making the plugin part of Unity doesn't make much sense. They could implement it more efficiently directly in the engine. The plugin API is pretty restrictive. I doubt they will do it though. They would have to implement it for a lot of platforms and I doubt it is something your average unity user will ever need.

I would personally say Unity has far bigger problems than gpu-cpu communication but I'm sure that is subjective.

 

I think Joachim said in the unite talk in Austin that there would be an async readback in Unity 2018.1

 

Just before I go ahead and plug this into my own project, does anyone know if the current version works on 5.6.3?

Also curious to hear if anyone has tried leveraging this async compute for any post-processing, or any general post-pro use cases for Async compute. IE. could you potentially speed up something like Eye Adaptation by using Async compute?

 

Any chance you could find a reference/link to the source of that for me? That would be amazing news for my current project.

I just decided to try switching over from DX11 (where this plugin works amazingly) to OpenGL 4.5 without thinking about it, and obviously this plugin doesn't run on OpenGL.

 

This would be the talk you are searching for:

 

They talk about it at 93 minutes+

 

18.1 has a beautiful named experimental called AsyncGPUReadBack which might work.

17.3 has CreateGPUFence, maybe this GPUFence can be used to peek at the texture?

 

Just adding some resources regarding the new (but still experimental) AsyncGPUReadBack here, in case anyone wants to look into it further. Someone already did some tests, using the new API for async screen capture:
https://twitter.com/_kzr/status/951760588127924224
https://github.com/keijiro/AsyncCaptureTest

 

Wow!! I think that is the best update coming with Unity3D ever in a new version. Looking forward for the final 2018.1 version!! Will bring procedural terrain creating with Unity3D to another level!

 

Hi, I'm trying to use the plugin made by Michal_ (AsyncTextureReader) for Android, it is working very well on the Editor, but I get the DllNotFoundException on Android Build. What could I do to make it work ?
I googled it and I believe I have to make a specific library for Android out of it , like a .so file. Is that correct ?
If so, how could I do that ?

Sorry, I'm not really a pro with Plugins. Any help will be appreciated, thank you. =)

 

What unity version are you using? Also, although I'm not sure it matters, what device and os did you test on for android?

Edit: I may have misread, did you try to use the given examples or did you try to build the plugin dll yourself?

 

I'm using Unity 5.6.4. I tried to use the DLL found in the UnityProject there : https://github.com/SlightlyMad/AsyncTextureReader
It works in the Editor but not in Android api lvl 24, with the error DLL not found. And so I guess I have to build it from the source code. Maybe I could made an aar. file out of it in Android Studio ?

Thank you for the help.

 

Did AsyncGPUReadback ever got OpenGL support?