World→pixel mapping. Usually from computeLayerFit for the same layer.
Index into ir.layers. Out-of-range or absent → nothing drawn (honest no-op).
OptionallineExtrusion stroke width in device px (default 1).
OptionalopacityLayer opacity in [0,1] via globalAlpha (default 1). Used to dim adjacent "ghost" layers.
OptionalprogressLive-progress "completed cut" (DD-006): the last printed segment index in THIS layer. Extrusion segments at or before it draw at full opacity; those after it draw at upcomingOpacity (not yet printed). Omit for no progress split. Honest — nothing is hidden, only dimmed.
OptionaltravelDraw travel moves too, in this style. Omitted/false → extrusion only (the default).
OptionalupcomingOpacity of not-yet-printed extrusion when progressCutSeg is set (default 0.15).
Per-segment color mode (shared with the 3D renderer). Applied to extrusion moves.