Interface HdrAssetDataAdvanced

Width of each cube face in texels, a power of two

Defaults to a quarter of the panorama's width, rounded down to a power of two, from 16 to 512. A 512 cube with its mips takes about 8.4 MB on the GPU and the same again in main memory, and each doubling takes four times that. Raise it only where a sharper sky is worth the memory.