Patterns Inside a Sketch
Use a sketch pattern to repeat geometry you have already drawn: a row of slots, a bolt circle, a symmetric outline. Select the primitives, pick a tool from the sketch toolbar's PATTERNS group, and the copies appear along with control geometry you edit on the canvas.
This is the 2D family. It repeats points, lines, arcs, circles, ellipses and placed SVG artwork inside one sketch, before anything has been extruded: a row of docking points and a bolt circle of imported artwork are each a pattern of one thing. The four tools that repeat finished solids carry a (3D) suffix on the toolbar and work nothing like these. Repeating a Body Along a Line and Repeating a Body Around an Axis cover those.
The group changes with your selection
Every tool in the group reads the selection, so the group's contents swap as that selection changes. With nothing selected, the four create tools are not on the toolbar at all. There is no greyed-out button, no tooltip and no message. If you went looking for Linear pattern and it was not there, you had nothing selected, and nothing else is wrong.
Select a primitive and Linear pattern, Rectangular pattern, Circular pattern and Mirror appear. Select a pattern instead, by clicking its hexagon, and those four vanish: Materialize pattern is what stands in their place. Add to pattern and Remove from pattern join it only when the selection also holds geometry to move in or out.
The four tools
| Tool | Repeats along | Numbers you can edit | Arrives as |
|---|---|---|---|
Linear pattern |
One direction | Count |
3, counting the original |
Rectangular pattern |
Two directions at once | U Count, V Count |
3 × 2 |
Circular pattern |
Around a centre point | Count, Total angle |
6 copies over 360° |
Mirror |
Reflected across a line | None | One reflected copy |
A rectangular grid starts at 3 × 2 here and at 3 × 3 in the 3D family, so the two do not open on the same shape.
The copies are not new drawings. They follow the originals, so editing the source geometry moves every copy with it, and the count stays a number you can change later.
The control lives on the canvas
There is no panel. Each tool seeds its own control geometry and draws a hexagon glyph carrying the tool's icon, plus a small numeric glyph for each number the pattern exposes: n=3 for a count, θ=360° for a total angle.
- Linear: one construction line, from a point pinned to the centroid of your selection out to a free tip with an arrowhead on it.
- Rectangular: two of those lines from the same pinned point, one running right and one running up.
- Circular: no line at all. A centre point off to one side, joined to the centroid by a dashed link.
- Mirror: a construction line lying horizontally through the centroid.
Click a numeric glyph and an editor opens on the field Count, U Count, V Count or Total angle. It takes a plain number, a parameter or an expression, so a bolt circle can be driven by holes and a slot row by slots - 1.
Clicking the hexagon selects the pattern; dragging it depends on the tool. Only a mirror can be dragged by its hexagon, which moves the whole axis. A linear or rectangular hexagon does not move: its anchor is pinned to the centroid, and what you drag is the free tip of the control line. A circular pattern has no line to grab, so you drag its centre point.
A count bound to a named parameter can drive this pattern and a quantity elsewhere from the same number: Named Parameters covers the binding.
Spacing is the length of the control line
There is no spacing field, in the editor or on the canvas. The spacing is the control line's length: pull the tip further out and the copies spread, push it in and they close up.
Dragging is the wrong way to set it when the number matters. That control line is a real construction line, so select it, press D, and type into the Length field: at 12.5 the row lands on 12.5 mm centres and stays there through every later edit. The dimension takes a parameter or an expression like any other, which is how a row of slots keeps up with a plate that grows.
There is no fixed starting spacing either. A new control line is as long as the diagonal of your selection's bounding box, falling back to 20 mm when the selection has no extent at all, such as a single point.
The circular centre starts off to one side
A circular pattern does not turn about the middle of your selection. Its centre point is seeded one bounding-box diagonal to the right of the centroid, sitting on nothing in particular, with a dashed line drawn from the centroid to show you where it went.
That makes every fresh bolt circle wrong on arrival: six copies of your hole swung around a spot in empty space. Drag the centre point onto the feature you meant, the middle of the plate or the axis of the boss, and the ring lands where you wanted it. The point is ordinary sketch geometry, so make it coincident with the centre you are patterning around and it holds there when the rest of the sketch moves.
Circular patterns and the total angle
A circular pattern spreads its copies across a total angle, stepping by that angle divided by the count. Six copies over 360° step by 60°, the last of them at 300°, and the ring comes out even. Drop the angle to 180° with the count still at six and the step becomes 30°, which puts the last copy at 150°.
If you type a total angle of zero it is refused:
Circular pattern total angle must be non-zero
The mirror that looks like it did nothing
A mirror seeds its line horizontally through the centroid of your selection, which folds the reflected copy back over the geometry it came from. The pattern exists, the hexagon is there, and the canvas looks untouched.
Drag the hexagon aside and the copy appears where it belongs.
The two points defining the line have to be different from each other. Collapse them onto one another and you get:
Mirror line points must be distinct
A copy is not geometry you can edit
Copies are derived. They are recomputed on every rebuild and the solver never sees them, so a copy takes no constraint and no dimension: click one and there is nothing selected to work on. Constrain the original and every copy follows it.
They do count as shape, though. Regions close over them and an extrude consumes them exactly like drawn geometry, so a patterned circle cuts its holes and a patterned outline builds its bosses without being materialised first. Regions and Profiles covers what the extrude sees.
Adding and removing geometry later
Click the hexagon to select the pattern, then shift-click the geometry you want to move in or out. Add to pattern appears once something in the selection is outside the pattern, and Remove from pattern once something in it is inside. Reach for them when the outline grew after you set the repetition up, rather than deleting the pattern and building it again.
Removing the last primitive deletes the pattern, without a warning and without an error. The copies vanish, the hexagon goes, and the control line and its two points stay behind as ordinary construction geometry that nothing points at any more. Undo brings the pattern back; otherwise delete the leftovers by hand.
What you cannot feed a pattern is the output of another one:
A pattern cannot replicate copies from another pattern
Pattern the originals and raise the count instead.
Materialise, and what it costs
Select the hexagon and press Materialize pattern: the pattern goes, and each copy becomes a line, an arc, a circle or a point stored in the sketch under its own id.
Two things survive that people expect not to. The control geometry stays behind, so the construction line, its pinned anchor and its tip are still in the sketch with nothing referring to them, and finding and deleting them is your job. And a materialised copy is not free geometry: it arrives carrying its own copy of the seed's internal constraints, so a baked copy of a constrained rectangle is still a constrained rectangle and will not drag out of shape.
Ellipse and SVG copies are the exception: they are not baked. Materialising a pattern of ellipses or of placed artwork removes the pattern and takes those copies with it, so keep that kind of repetition parametric.
When it fails
The refusals are short and they say exactly what to fix.
| Message | Cause |
|---|---|
| A pattern cannot replicate copies from another pattern | A copy was in the selection. Select the originals |
| Pattern count must be at least 2 (including the original) | The original counts as one, so 1 makes no copies |
| Rectangular pattern must produce at least one copy (uCount × vCount >= 2) | Both legs came out as 1. A grid of one cell repeats nothing |
| Rectangular pattern axes must not be parallel | The two control lines ended up pointing the same way |
| Pattern direction is degenerate (zero-length vector) | A control line collapsed onto its own anchor |
| Pattern spacing must be greater than 0 mm | The same collapse read from the spacing side: the line's length is the spacing |
| Circular pattern total angle must be non-zero | Give it an angle to spread the copies across |
| Circular pattern requires a center point | The pattern's centre point is no longer in the sketch |
| Mirror line points must be distinct | The two ends of the mirror line landed on top of each other |
| A primitive referenced by this pattern no longer exists | Something the pattern repeated was deleted |
One case is a warning rather than a refusal. A rectangular pattern whose two legs point almost the same way still builds, and tells you:
Rectangular pattern axes are nearly parallel (< 5°)
The result is a grid squashed into a line. It is legal, it is almost never what you meant, and the fix is to drag the second leg of the control until the two directions separate. Push them all the way together and the warning becomes the refusal above it.
See also
- Repeating a Body Along a Line: the same idea applied to finished solids
- Repeating a Body Around an Axis: the 3D ring, and why it counts its copies differently
- Dimensions: putting an exact length on the control line
- Regions and Profiles: what the repeated outlines become when you extrude