Convert a line weight / length already expressed in mm-on-paper terms
is a no-op; this converts a MODEL-space length (metres) to mm on paper
at the given transform's scale — e.g. for stroke widths authored in
world units. Most line/hatch weights in this codebase are already
mm-on-paper constants, so this is only needed where a length is
genuinely world-space (kept separate from worldPointToPdfMm so
callers can't accidentally apply the Y-flip/offset to a scalar).
Convert a line weight / length already expressed in mm-on-paper terms is a no-op; this converts a MODEL-space length (metres) to mm on paper at the given transform's scale — e.g. for stroke widths authored in world units. Most line/hatch weights in this codebase are already mm-on-paper constants, so this is only needed where a length is genuinely world-space (kept separate from
worldPointToPdfMmso callers can't accidentally apply the Y-flip/offset to a scalar).