Add a Marching Cubes external sample.

[tcoppex]

Hi,

This sample demonstrates how to dynamically generate procedural meshes based on a signed distant function using a multi-pass marching cubes algorithm on the GPU. It also demonstrates tri-planar mapping and integrates an Ambient Occlusion calculation in the final vertex generation stage.

Live preview: https://tcoppex.github.io/webgpu-marchingcubes/

Cheers.

[kainino0x]

This is a nice sample! Unfortunately it is having issues on Mac :(
Most likely some kind of undefined behavior (out of bounds?) but let us know if it looks like a Chrome bug.

[tcoppex]

Hi @kainino0x,

Thanks for your feedback! It does seem like an out-of-bounds issue. So far I've only tested it on Chrome v129.x on Windows 11, as browser builds don't appear to be compliant yet on GNU/Linux. I'll get back to you if I find anything. In the meantime, I'll mark the PR as a draft.

Thanks.

[tcoppex]

While I'm not 100% sure why it worked, the issue should now be resolved on Mac.

I reduced the size of the density volume, which mainly affected the compute workgroup size. Despite it was still within general device limits (as defined by https://web3dsurvey.com/), it has done the trick.

[kainino0x]

Nice! Thanks for the sample!