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. Two of the four ask you to point at something first.
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. Add to pattern and Remove from pattern take their place, and only when the selection also holds geometry to move in or out. Click a copy rather than the hexagon and you get Select pattern, which swaps the copies for the pattern that made them.
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. Every pattern draws a hexagon glyph carrying the tool's icon, plus a small numeric glyph for each number it exposes: n=3 for a count, θ=360° for a total angle. Linear and rectangular seed their own control geometry; circular and mirror take the geometry you pointed at.
- 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. The centre point you picked, joined to the centroid by a dashed link.
- Mirror: the line you picked, or the line through the two points you clicked.
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.
A circular pattern asks where it turns
Circular pattern creates nothing on the spot. It enters a pick, with a banner along the bottom reading Click the point the pattern turns around, or click empty space to place it., and the copies are drawn as a preview while you aim, so the ring is on screen before anything is written.
Click the point you mean — the centre of a hole, a corner of the plate, a construction point you dimensioned earlier — and the banner becomes Rotation centre set. Confirm to create the circular pattern. Enter, or the banner's Confirm, writes the pattern. Escape abandons it and hands your previous tool back.
Click empty canvas instead and a point is placed there through the same snap-and-constrain path every drawing tool uses, so a centre dropped on a circle's rim or a line's midpoint stays on it, held by the constraint the snap emitted, rather than floating free beside it.
A centre you pointed at stays yours. Deleting the pattern leaves the point behind, because it may be a construction point the rest of your sketch is built on; deleting the point deletes the pattern.
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
A mirror asks for its axis
Mirror enters the same kind of pick, with the banner Click the line to mirror across, or click two points to define it. Point at a construction line you have already drawn and dimensioned and that line is the axis, which is the case worth knowing about: the reflection is then held by a line the rest of the sketch already controls. Otherwise click two points, and the second one completes the pick.
The reflected copy is previewed while you aim. Enter or Confirm commits it; Escape takes back whatever the pick placed.
Once the pattern exists, its hexagon sits on the middle of the axis and dragging it slides the whole line, which is how you walk the copy away from the original without touching either endpoint.
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 live geometry
Copies are derived: nothing stores them, and they are recomputed on every rebuild. That used to mean you could not touch one. Now you can. The cursor snaps to a copy's points, its midpoints and its curves, and any constraint you can put between two drawn primitives you can put between a drawn primitive and a copy — end a line on a copy's corner, make a circle tangent to a copied circle, dimension from a copied hole to the edge of the plate.
What holds it is not a snapshot of where the copy happened to be. The solver is told what the pattern is — reflected across that line, turned by that step about that centre, offset by the control line's own span — so the relation survives every later edit. Change the count, drag the direction line, move the original: the geometry you constrained follows, and it follows in both directions. Dimension to a copy and the dimension drives the seed, because the copy has nothing of its own to move.
Two things a copy still will not do. You cannot drag one — it has no position of its own; drag the original. And you cannot edit one: there is no stored primitive behind it to make construction, to export, or to seed another pattern from.
A constraint against a copy names that copy. Count the pattern down past it, take its original out of the seed, or delete the pattern, and the constraint has nothing left to hold on to: it is removed, and a message says how many went.
They count as shape, too. 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. 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.
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