Efficient vertex mesh updating in realtime

[dafteran4]

I have a soft body simulation on CPU and would like to upload changed vertex coordinates and normals every frame. I am currently doing this by storing Handle<Mesh>, then getting the Mesh asset and modifying its vertex attributes. This works, but it takes quite a performance hit. Is there some other way I could go about this?

[JMS55]

Uploading large amounts of CPU data to the GPU is expensive, there's not really a workaround. That said there might be unnecessary overhead in Bevy on top of the graphics APIs, I don't know.

[dafteran4]

Yes, I realize that. Though it seems I am orders of magnitude away from pci bandwidth limit. Anyway, I'll be looking into some other ways. I'll try to upload as little as necessary and do veretx positioning on GPU. I'm now looking into ways how to efficiently upload uniform data, similarly to how it's done in SkinnedMesh using BufferVec for updating the matrix. Are there any simpler examples for this, beside the actual skinning implementation?

[dafteran4]

Testing this further, I am getting much faster performance when using as few Mesh objects as possible. Then updating vertex attributes is fast enough. It seems my initial performance hit was more due to having a large number of Mesh objects.

[IceSentry]

Do you have a number for large here?

[dafteran4]

A few thousand cca, all mutated every frame. This dropped fps to about 40.