Plane

Status: Implemented

Plane creates a named construction plane for sketches and other references. It produces no solid: it registers one named frame (origin + normal) that later features resolve by name, drawn in the viewport as a soft-blue, selectable plane.

Walkthrough

Inputs

• id (string, default null) – identifier under which the frame is registered.
• orientation (options, default XY) – one of the world-aligned bases (XY, XZ, YZ). Used when no datum reference is given.
• datum (reference_selection, PLANE / FACE, default null, multiple: false) – an optional reference to an existing plane or planar face. When present it takes priority over orientation: the new plane inherits that reference's origin and normal.
• offset_distance (number, default 0) – distance to shift the plane along its own normal.

Behaviour

• With no datum, the plane passes through the origin. offset_distance then moves it along the normal, and its in-plane axes are the ones a sketch derives when it references the plane.
• The frame is registered under the feature's own id, so other features can pick it through a PLANE selection filter or by name.
• If the datum reference cannot be resolved (for example the referenced face was removed), the feature registers no frame and records the reference as unresolved rather than falling back to a world plane.

Notes

• The orientation normals are XY → +Z, XZ → −Y, YZ → +X, so a positive offset_distance on an XZ plane moves it in −Y.

Frames for planar face references

A sketch or construction plane referencing a planar face uses its outward normal as z. Its origin is the centre of the world-axis-aligned bounding box of the face boundary samples, projected onto the face plane. Each non-degenerate boundary edge contributes five equally spaced parameter samples, including its endpoints; holes also contribute. This sampled extent defines the origin even when a curved edge reaches farther between samples.

The in-plane axes follow the document's normal-based frame convention. With a unit normal z, choose up = +Y, except when abs(z · +Y) > 0.9, where up = +X. Then x = normalize(up × z) and y = normalize(z × x). The reference's own in-plane axes do not determine these derived axes. Datum plane references retain their registered origin and normal before this normal-based convention supplies the sketch axes.