Parse a .spz file. onProgress reports a 0..1 fraction (the gzip inflate happens up front as a single step, then per-splat unpacking streams the fraction toward 1).
.spz
onProgress
Optional
Parse a
.spzfile.onProgressreports a 0..1 fraction (the gzip inflate happens up front as a single step, then per-splat unpacking streams the fraction toward 1).