decimals property
Decimal places for every number written.
Six. Vertices live in a Float32List, which carries around seven significant decimal digits, so sixteen places would spend half the file spelling out the noise past what the source could represent. Three places is a millimetre on a metre, which is visible as faceting on anything hand-modelled at that scale. Six resolves a micrometre on a metre and still fits inside what the source float actually knew.
Trailing zeros are trimmed, so an axis-aligned box costs 1 rather than
1.000000 per coordinate without losing a digit anyone could read back.
Implementation
final int decimals;