SketchPOLin the studio

Polygon

Polygon draws a regular closed outline of three to sixty four equal sides in the sketch editor, from its centre and a corner, its centre and the middle of a side, or the two ends of one side. The number of sides is typed, or changed with the up and down arrows.

What it is

Polygon draws a regular outline: all its sides of equal length, all its corners equal. It has four sides each time you arm it, and you type another count before you start, or change it with the arrow keys at any step. There are three ways to set it out:

Inscribed, the way it starts: a centre, then a corner. The corners lie on a circle through the point you give.
Circumscribed: a centre, then the middle of a side. The sides touch a circle through the point you give.
By edge: the two ends of one side. The polygon is built on the left of that side, going from the first end to the second.

When to use it

Drawing a hexagonal or octagonal window, or a polygonal pattern area.
Setting out a regular shape on a side that already exists.

The steps

Arm Polygon. In the sketch editor (see Select for the ways in), type P, O, L quickly, or click Polygon on the editor's toolbar. The hint shows the sides and the way in force, such as 4 sides, inscribed.
Set the sides and the way. Type the number of sides and press Enter. Press I for inscribed, C for circumscribed, or E to switch to by edge and back. These keys work before the first click. The up and down arrows add or take away a side at any step.
Click the centre, or the first end of the side. It snaps to corners, middles, the centres of arcs, crossings, the dimmed shape in force and the lines of the view.
Click the corner, the middle of a side, or the second end. The polygon follows the pointer, turned towards it. Click to draw it. Or point in the direction you want, type the distance from the centre (or the length of the side, by edge) in the project's units, and press Enter; a point typed as x;y or @dx;dy also works.
Carry on. The polygon is drawn and left selected, and the tool is ready for the next one with the same count and way. Escape drops the first point, then goes back to Select.

What it refuses

Fewer than three sides or more than sixty four. A typed count outside that range is refused with a polygon has 3 to 64 sides. The arrows stop at those limits.
A corner on the centre. A second point on the first makes no shape, and the hint says so.
Changing the way after the first click. I, C and E only work before the first point.
A centre typed as numbers. Before the first click, typed digits set the number of sides. Click the centre.

What it writes to the contract

Nothing until you press Done. Each polygon is one step inside the editor, and Ctrl+Z steps back through them. The contract changes when you press Done, or Enter with nothing in progress, as one step you can undo: what the lines enclose becomes the window's or door's profile, points [u, v] in metres across the wall and up from the floor, or the pattern area's outline in the room's floorAreas or ceilingAreas, points [x, y] in plan metres.

A polygon is plain corners, one point each, with no bulge. A square set out by edge on a 1 meter side, as a floor area:

Common questions

How do I draw an octagonal window 80 centimetres across its flats?

Press P, O, L quickly, type 8 and press Enter, press C for circumscribed, click the centre, then type 0.4 and press Enter: the middles of the sides land 40 centimetres from the centre.

How do I draw a polygon on an existing side?

Press E before the first click, then click the two ends of the side. The polygon is built on the left of the side as you go from the first end to the second.

Can I change the number of sides while drawing?

Yes. The up arrow adds a side and the down arrow takes one away at any step, and the preview follows.