Offset
Purpose
Offset creates a parallel to a single element: a parallel line to a line, a concentric circle to a circle, the shifted curve to an arc, rectangle, polyline, spline, ellipse or elliptical arc. The original stays. On which side and at which distance the parallel is created is shown by the mouse as a preview; an exact value goes into the field D.
For a whole contour of several elements — with transitions at the corners — use the CAM offset.
Access
- Ribbon: group Modify, split button Offset (3) — head of the family.
- Classic toolbar: group Edit, family Offset (4).
- Key: O.
- Command search : Offset.
Procedure
- Click the element (1) — it is highlighted, the field D: appears with the last used distance (default 10.00); the status line reports Offset: mouse = side + distance · enter D for an exact value. For an ellipse or a spline the field additionally carries the button for the result type, and the message ends with · Tab + Space = result type.
- Move the mouse (2): the preview shows the parallel on the pointer's side, the distance follows the mouse and appears in the field. A click accepts the current distance — or you type D and press Enter; then the typed distance applies on the side where the pointer last was.
The status line confirms Offset created (D=20.00). The tool stays active for the next element; Esc ends it.
Result type for ellipse and spline
The parallel curve of an ellipse is not an ellipse itself, and the parallel of a spline is not a spline with the same control points. The program therefore computes the exact parallel curve and stores it as a polyline. If you prefer a smooth element instead of the polyline, choose the result type in the floating field:
The floating field moves away from the mouse; the button is therefore operated with the keyboard, as in the chamfer field: Tab moves the focus from the field D to the button (frame visible, a tooltip explains the choice), Space or Enter cycles onwards, Tab returns to the field. The preview changes visibly with every step; the status line reports Offset result: ….
| Result type | Source | What is created |
|---|---|---|
| Polyline (default) | ellipse, spline | the exact parallel curve as a polyline — the distance is correct everywhere |
| ∽ Spline | ellipse, spline | a smooth spline through points of the exact parallel curve (few control points, deviation in the thousandths range) |
| ≈ Ellipse | ellipse and elliptical arc only | an approximating ellipse with the semi-axes rx ± D and ry ± D; the distance is exact only at the vertices and deviates in between |
When placing as an ellipse the program measures the largest deviation from the nominal distance and appends it to the message: Offset created (D=10.00) · approximation: deviation up to 0.50 mm. The more the ellipse differs from a circle and the larger D, the larger the deviation.
A spline is only possible if the parallel curve has no sharp corners. With a large offset inwards the parallel curve is clipped where it would intersect itself (inner offset larger than the smallest radius of curvature); then it stays a polyline and the message says · spline not possible (sharp corners) — polyline.
The last chosen type is remembered per source type (ellipse, spline) in the settings and is preset again at the next offset and after reloading; it also applies when you type D and confirm with Enter.
For line, circle, arc, rectangle and polyline there is no button — the result is unambiguous there.
What is created
| Original | Parallel |
|---|---|
| Line | line of the same length, shifted in parallel |
| Circle | concentric circle with radius ± D (inwards only as long as the radius stays positive) |
| Arc | concentric arc with the same angles |
| Rectangle | larger or smaller rectangle by D |
| Polyline | shifted curve; inwards, pieces may overlap |
| Spline | exact parallel curve as a polyline or a smooth spline — according to the chosen result type |
| Ellipse, elliptical arc | exact parallel curve as a polyline, a smooth spline or an approximating ellipse — according to the chosen result type; the arc keeps its end angles; an inner offset that is too large is clipped at the intersections |
If the distance inwards is too large for a circle, arc or rectangle, the program reports Offset not possible (distance too large or too small). A click very close to the element is rejected (Offset distance too small — move the mouse further away or enter a value). Texts, images, points and block instances have no offset (No offsettable element at the click point (line/circle/arc/rectangle/polyline/spline/ellipse)).
Options and relations
- The parallel is created on the active layer with its attributes; in auto mode 0 it takes layer, colour and width of the clicked element.
- The result type for ellipse and spline is remembered in the settings (per source type), see result type.
- The last accepted distance is in the field again at the next call.
- Two parallels at once — e.g. for a wall — are drawn by the double line; dimensions and hatches are not copied by Offset.
Related commands
- CAM offset — shifted contour of several elements with corner radii
- Double line
- Ellipse · Spline — the sources with a selectable result type