Linear Dimension

Status: Implemented

Linear dimensions measure the distance between two vertices and project the result into the active PMI view. Use them to document edge-to-edge spacing and critical offsets without altering model geometry.

Inputs

• annotationID – optional identifier stored with the PMI payload.
• decimals – decimal precision; defaults to the PMI mode dimDecimals preference.
• aRefName / bRefName – vertex references that define the measured span.
• planeRefName – optional face or datum plane that controls projection.
• alignment – lock the dimension to the view plane or one of the global axes (XY, YZ, ZX).
• offset – distance to shift the dimension line away from the measured span; dragged labels update this value automatically.
• showExt – toggle extension lines from anchors to the offset dimension line.
• isReference – wraps the display text in parentheses when set.

Behaviour

• Distance is recomputed whenever anchor geometry updates; labels stay associative.
• Arrowheads and extension lines scale with screen distance so dimensions remain legible at any zoom.
• Labels can be dragged; the system captures the world position and extension offset for repeatable layouts.
• Dimensions respect PMI inspector formatting hooks such as formatReferenceLabel for dual-units or reference styling.

Usage Tips

• Pick a projection plane when the default view alignment produces ambiguous results (e.g., angled faces).
• Use alignment = view with the PMI triad to quickly dimension sketch-like layouts, or axis alignment to match drawing standards.
• Combine with reference dimensions to communicate non-driving measurements without cluttering the model.