The Pen builds a path one anchor point at a time. Click to set down a corner; press and drag to set down a smooth point and pull out its handles; come back to the first point to close the shape. It is the tool for outlines that must be exactly so.
What it does
Press P, or choose ‘Pen’ on the rail.
- Click to place a corner anchor. The next click joins it with a straight line.
- Press and drag to place a smooth anchor and pull out a pair of handles, equal and opposite. The one under the pointer shapes the segment to come; the one behind shapes the segment you have just made.
- Between clicks a line stretches from the last anchor to the pointer. It is not a guess: it is the very curve the next click will make, placed by the same rule.
- Click the last anchor again to take away its outgoing handle, so the next segment leaves it straight: a corner after a curve. Drag from there to pull out a new handle on that side only.
- Close the shape by pressing the first anchor once there are at least three. The target is generous, 14 screen pixels, or 30 for a finger. The shape completes when you let go, so you can drag first to shape the closing curve.
- Finish without closing with Enter, or with a Command-click (Ctrl-click): the path is closed with a straight line back to its start, because a cut needs an inside. A path of fewer than three anchors is discarded. Escape abandons the path; Backspace or Delete takes off the last anchor.
- A path with nothing inside it does not finish, however you close it: anchors that all lie on one line enclose nothing, so there is nothing to cut. The Pen says so and keeps the path open. Add an anchor off the line and close it again. Snapping makes this easy to do by accident, because anchors caught on one edge of the sheet, or on one 45° line, all lie on a line.
As it places an anchor, the Pen snaps. Within 8 screen pixels it catches the sheet’s corners, its edges, its center lines, the anchors of every shape already drawn, and lines at 45° steps from the previous anchor. A magenta guide shows what has caught. An edge fixes only one direction, so along it the Pen still looks for an anchor or a 45° line crossing it, and a slanting cut can end exactly on the edge of the sheet. Edges catch only alongside the sheet, not out along their extension.
The modifiers, while a path is under way:
- Shift puts the next anchor on a 45° line from the last one, instead of snapping. While you drag a handle it holds the handle to 45° steps. It takes effect the moment you press it, without waiting for the pointer to move.
- Option (Alt) during a handle drag breaks the pair, so only the handle you hold moves; let go of Option and they pair up again. Option-click or Option-drag an anchor of a shape already on the canvas and the Pen converts it, as Curves would.
- Space during a handle drag moves the anchor itself, handles and all; let go and you are pulling the handle again from where you left it.
- Command turns snapping off while you hover, or while you move an anchor with Space. A Command-click still finishes the path.
With no path under way, a click always starts a new one, even on top of an existing anchor or outline, where it snaps on. That is where a notan’s next cut very often begins. Between paths the three modifiers lend you the other tools while they are held: Command for Move, Option for Points, Shift for Curves.
A finished path goes wherever a drawn shape goes. Over the sheet it becomes a cut, and its piece is folded out over an edge; see Flipping.
Why it works this way
The Pen follows Illustrator’s conventions closely, because it is the tool people learn once and carry from program to program. Its details here come from what a notan needs.
Snapping exists for the edge. A cut that stops half a unit short of the sheet’s edge leaves a thread of paper holding the piece in, invisible on screen and fatal with a knife. So the Pen reaches for edges, corners and the points of earlier cuts, which is where the next cut usually wants to start or finish.
Shift replaces snapping rather than adding to it. Two rules fighting over one point would make neither exact.
The idle Pen once added a point when you clicked an existing outline and deleted one when you clicked an anchor, as Illustrator’s does for a selected path. Here nothing is selected while you draw, so it applied to every shape, and a new cut could not be started on an old one’s point. That job went to Points, one held key away.
A path with nothing inside is kept rather than thrown away, because it is several clicks of work and one anchor off the line makes it a shape. A single stroke of the pencil that encloses nothing is only one gesture, and makes nothing, as a flat drag does with Rectangle.
Closing on release rather than on press lets the last gesture shape the closing curve. A slight wobble during a plain click is ignored, so it cannot replace a smooth start point’s handles with a tiny, crooked pair.
The metaphor
The Pen is the least pen-like tool on the rail. A real pen touches the paper all along the line; this one never touches it between points. What you really do with it is what a draftsman did in two stages: plot the points, then ink a fair line through them along a straight edge or a French curve. The inking was done with a ruling pen, which held ink between two steel blades set a fixed distance apart. From 1953 Rotring’s Rapidograph, with a fine tube fed from a cartridge, gave an even line with less fuss and largely replaced it.
The metaphor breaks at the line itself. Ink has width, weight and wetness. A path has none of them: it is a boundary with no thickness at all, the ideal edge a knife would follow if a knife could be perfect. What the Pen draws is not a mark but a decision about where one color stops and another begins.
A history
In art
Artists have always drawn with pens, of cut reed, of quill, of steel, and a pen drawing is usually prized for the life in its line: Vincent van Gogh’s reed-pen drawings made at Arles are dense with marks you can feel the hand in. The Pen tool descends from a different tradition, the constructed line. In 1509 Luca Pacioli printed Roman capitals built with ruler and compass in De divina proportione, and in 1525 Albrecht Dürer showed how to construct letters, among much else, in his manual of measurement. A letter became a set of instructions that any careful hand could follow. The Pen tool is that idea made quick.
In printing
Adobe was founded in 1982 by John Warnock and Charles Geschke, and its PostScript language, which reached the market in Apple’s LaserWriter printer in 1985, described the shapes on a page as outlines made of straight lines and cubic Bézier curves. Letters became outlines too, printed at any size from the same curves. Adobe Illustrator, first released for the Macintosh in 1987, grew out of Adobe’s in-house software for drawing type and gave designers a pen for making such outlines directly. Its Pen tool fixed the grammar, click for corners and drag for curves, that nearly every drawing program has used since.
In technology
The mathematics came from the car industry. In 1959 Paul de Casteljau, at Citroën, worked out how to compute a smooth curve from a handful of control points by nothing more than repeatedly taking points part of the way along straight lines, a construction you could make with a ruler. Citroën kept it in house. In the 1960s Pierre Bézier at Renault found the same curves independently and published them; he built them into UNISURF, Renault’s system for designing car bodies, and his is the name that stuck. The polynomials underneath had been described by the mathematician Sergei Bernstein in 1912, for quite another purpose.
De Casteljau’s construction is still at work here. Adding a point to an outline means splitting one curve into two that trace exactly the same line, and the split is his.
In professional software
The Pen is the tool vector programs share most closely, down to its key, P, and its grammar: click for a corner, drag for a smooth point, press the first point to close. CAD programs build the same outlines from polylines and splines, placed with typed coordinates and snaps.
- Adobe Illustrator. The Pen (
P) is the model for this one. Hold Space during a drag to reposition the anchor, Option-drag (Alt-drag) a handle to break the pair, and click the last anchor to take away its outgoing handle. Unlike this Pen, it will leave a path open, as a line with a stroke. - Adobe Photoshop. The Pen (
P) works the same way; first choose ‘Shape’ or ‘Path’ in the options bar. A path, kept in the ‘Paths’ panel, is usually a means to an end: a selection, or a vector mask for cutting a subject out of a photograph. - Figma. The Pen (
P) draws vector networks, in which any point can join more than two segments, so a shape need not be a single loop. - Inkscape. The Pen tool (
B, for Bézier) has modes in its toolbar: regular Bézier, Spiro, BSpline, and paraxial lines that run only horizontally and vertically. Enter finishes a path and Escape cancels it. - Autodesk AutoCAD.
PLINEdraws one object from straight segments and arcs, andSPLINEdraws a curve through fit points or pulled by control vertices. Object snaps (F3) catch endpoints, midpoints and intersections, much as this Pen snaps, and polar tracking (F10) holds angles as Shift does here. - Autodesk Fusion (formerly Fusion 360). The Line tool (
L) draws connected lines, and pressing on the last point and dragging draws an arc tangent to it. For free curves, choose Fit Point Spline, which passes through its points, or Control Point Spline, which is pulled by them.
What carries over. Click for corners, drag for curves, and use as few anchors as will do: fewer points make a smoother path in every program. The pitfall is the open path. Illustrator, Photoshop and AutoCAD will all leave one, and a cutting machine may follow it as a single line rather than around a hole, so close every outline that should become a cut.
Try this
- Start on the top edge of the sheet, where the anchor snaps on. Click once well inside the sheet, click again back on the top edge, then press the first anchor to close. The cut meets the edge exactly.
- Make a shape entirely from press-and-drag anchors, then press and drag on the first anchor to shape the closing curve before you let go.
- Halfway through a handle drag, hold Space and move the anchor; let go of Space and carry on shaping.