The original tool can be found here...
What's been updated:
- Much faster setup (keep an eye on fps and performance monitor), normally the clouds are static an no shadows need to interact with them, if that's the case then the old setup is enough since you are going to bake it once.
- More lighting details, the previous setup relied on point scatter (100K) and now there is no need for that, we are baking light straight into the voxels (925K nine times more) and transfer them to the high res version, no need for that middle step anymore.
I was thinking of adding point light also (we are only using direct light here), let me know if you are interested, and any other features are more than welcome to suggest.
The video is fast forwarded x4.