[SOLVED] Problems with taking a screenshot in LWRP

I'm trying to capture some screenshots for my game. They need to be saved as jpgs to a folder, latency is not an issue, I don't care if it happens over 10 seconds. My number one priority is to keep the game at a steady framerate.

Some things I've tried:

• ScreenCapture.CaptureScreenshot but that is super slow and the game hangs for a split second.
• The old method of texture2d.ReadPixels() and EncodeToJPG() but that was unbelievably slow.
• I also found a relatively new feature: https://docs.unity3d.com/2018.3/Documentation/ScriptReference/Rendering.AsyncGPUReadback.html
  • I found a repo using this feature to capture screenshots asynchronously: https://github.com/keijiro/AsyncCaptureTest
  • This requires the use of OnRenderImage(), but I'm using LWRP and OnRenderImage() isn't called in SRP.
• RequestASyncGPUReadback and Command Buffers: https://pastebin.com/StVKMkfX
• Scriptable Render Pass: https://pastebin.com/VCjXR4eB
• Combining Scriptable Render Passes and RequestAsyncGpuReadback: https://pastebin.com/VYCDekPy
• Pulling my hair out
  

I found a LWRP example here: https://github.com/UnityTechnologies/LWRPScriptableRenderPass_ExampleLibrary
However, this is just used for image effects. I have no idea how to take the contents of the screen and put it into an image file.

The docs for LWRP kinda suck and the examples I've found aren't well commented. To say that I have no idea what I'm doing in SRP is an understatement. Pls help

 

How slow is the actual ReadPixels call in comparison to the encoding and saving part? You could write a few hundred bytes to the file every frame in a coroutine if the the ReadPixels call is quick enough.

I'm also not sure that players really expect the game to maintain 60 FPS while taking screenshots, so is that aspect really necessary?

 

ScreenCapture.CaptureScreenshot took ~200ms.

ReadPixels() is 40-70ms.
Texture.Apply() is ~5ms.
EncodeToJPG() is 35-50ms.
GetRawTextureData() is ~10ms.
File.WriteAllBytes() is <1ms.

All up, the render texture method was about half the speed of ScreenCapture.CaptureScreenshot, but that's pretty meaningless because both are way too slow.

ReadPixels has to be done all at once because if I split that over several frames the pixels will have all changed. EncodeToJPG can't be split over multiple frames. And File.WriteAllBytes is fast enough as it is. Also, unity isn't thread safe so the only thing in all this that I could dump on another thread is File.WriteAllBytes, but again, that's already fast enough as it is. GetRawTextureData is slightly faster than encoding, but that's a bit useless because then I can't actually see the image.

I need this to be taking screenshots in the background about every 10-15s, it'll just overwrite old files leaving a maximum of about 5-10 screenshots at any time. Right now the game has very very noticeable stutters. Not ideal.

 

Solved here: https://gamedev.stackexchange.com/q...performance-screenshots-in-lwrp/169396#169396