Maps a view-space depth to a logarithmically-staggered depth slice index, so cells stay thin
near the camera and widen towards the far plane (same family of formula as the existing CSM
log/uniform split, see DirectionalLight.updateCascades()).
Parameters
viewZ: number
View-space depth (positive distance from the camera).
Maps a view-space depth to a logarithmically-staggered depth slice index, so cells stay thin near the camera and widen towards the far plane (same family of formula as the existing CSM log/uniform split, see
DirectionalLight.updateCascades()).