Coastal cloud bank

Density volumes derived from the JangaFX EmberGen Cloud Pack (CC0 1.0):
https://jangafx.com/software/embergen/download/free-vdb-animations
Original archive SHA256:
3676ba4c7ac431446731f956f98e925ad3db31354b8b4adcb137dc0250595f73

cloud07.bin: cloud_07_variant_0000.vdb, resampled R8 UNORM, 127 x 192 x 77.
SHA256 9f1c97a33eecfd10e4bf1ac1c17c266330a7602f1da8351c053ab3a4997f6465
cloud01.bin: cloud_01_variant_0000.vdb, resampled R8 UNORM, 103 x 192 x 69.
SHA256 f065906970664c1e0b52694dcc74ca701bef944454a89bbd427241be0012c5df
Both retain native XYZ storage, four zero border voxels and maximum-density
normalization. The rendering samples native UVW as Three.js box coordinates ZXY.
See CC0-LICENSE.txt for the publisher's full license.

Ray/box traversal is adapted from Three.js r180 webgl_volume_cloud.html:
https://github.com/mrdoob/three.js/blob/r180/examples/webgl_volume_cloud.html
See THREE-LICENSE.txt for the MIT license.