Share buffer between CUDA and wgpu

[anderspitman]

I have a CUDA codebase that I want to explore porting to WebGPU, mostly for portability reasons and to avoid vendor lockin. It would be very difficult to port the entire codebase at once, especially because we currently rely on CUDA's nvcomp library for gzip decompression.

It would be nice if I could leave the beginning stages of our pipeline in CUDA, then export a raw pointer to the results in GPU memory, then run WebGPU shaders to operate on the data for the following stages. Is anything like this possible with wgpu?

I believe this is an example of basically what I'm going for but with CUDA+Vulkan:

https://www.gpultra.com/blog/vulkan-cuda-memory-interoperability/