Pointcloud Data to Unity VFX Graph Flickering

Software Unity
1

Hi all :wave:

I’ve been working on getting the ZED camera point cloud into Unity’s VFX Graph by feeding it data via Graphics.Blit() from the ZED SDK’s GPU textures (XYZ, Color, and Confidence). The textures are copied into intermediate RenderTextures and passed to the graph as exposed Texture2D properties like this:

in the ZEDPointCloudManager component provided by Stereolabs i do


    public RenderTexture XYZTextureCopy;

    vfx.SetTexture("XYZTex", pointCloudManager.XYZTextureCopy);

then I trigger the texture copy in LateUpdate() like this:

if (XYZTexture != null && XYZTextureCopy != null) 
{
    Graphics.Blit(XYZTexture, XYZTextureCopy);
}

This is my VFX Graph

image
image2038×1708 230 KB

Output

this is the original pointcloud as reference and the VFX Graph pointcloud layed on top

output_half

:toolbox: Setup Details

  • Unity 6000.0.44f1
  • ZED SDK 5.0.3
  • CUDA 12.0

:white_check_mark: What Works

  • The pipeline technically works: I see particles in the VFX Graph positioned via ParticleID → UV → Sample XYZTex
  • Color and Confidence sampling also works when wired into the graph
  • I verified the XYZ values with a manual ReadPixels() readback — data seems valid when read

:x: What’s Not Working

  • I get severe flickering in the point cloud in VFX Graph
  • Large portions of the cloud randomly disappear
  • Meanwhile, the native rendering using the same texture directly with Graphics.DrawProceduralNow() in OnRenderObject() is totally stable

:question: My Main Questions

  1. Is it possible that Graphics.Blit() copies the texture while ZED is still writing to it?

    • Could this cause the VFX Graph to sample from an incomplete or zeroed region?

  2. What’s the right way to safely duplicate a ZED GPU texture for use in VFX Graph?

    • Should I be double-buffering? Using CommandBuffer? Or AsyncGPUReadback?

  3. Why is DrawProceduralNow() stable, while the VFX Graph version flickers — even though both use the same texture source?

  4. Is there any kind of GPU synchronization mechanism I’m missing?

If anyone has successfully brought ZED point clouds into VFX Graph without this kind of visual instability, I’d love to hear how you managed it. Could really use insight on how to safely hand off those textures across frames.

Thanks a lot in advance!

Sebastian

2

Hi,

I’m not super familiar with VFX graphs themselves, so I won’t be able to help you a lot on that part.
Yes, you can quickly try to use a buffer to make sure the data is not overwritten. It should be quite fast to test.
The DrawProceduralNow function is called directly (as you can deduce by its name) without adding it in the rendering queue, which may explain why it’s working fine; the data is not updated yet at the time of the call.

I would need to do more tests to be sure of what’s happening. I’m just sharing ideas out loud here.

Please let me know if you find something on our side, I’ll do the same.

Best,