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draw compass
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Draw a construction circle from a center and a point, tick its crossings, then hide the circle.
Menu: Draw > Compass | In depth: Compass & straightedge
The Straightedge with a circle in place of a line, and the same bargain: you get a full construction circle to work with, you mark what matters on it, and then the circle goes away and the marks stay.
First, the circle. Click the center, then a point on the rim. The gap between them is the radius, which is exactly how a physical compass is set. You get a real, visible circle, so everything crosses it and everything snaps to it while you work.
Then, tick mode. Every click now marks that circle rather than drawing something new:
- Click to drop a tick. On a crossing it sits on a real intersection point that keeps up with the crossing; anywhere else it sits on a point that rides the circle.
- Drag to strike an arc: a real arc along the circle from where you pressed to where you released, snapped to points and crossings at both ends. This is the arc-through-two-crossings mark that classical constructions are made of.
- A drag that ends where it began marks nothing, and leaves nothing behind.
Enter or Escape finishes. The circle, its center and rim points, and every anchor the session made retire into a hidden helper group. Your ticks and struck arcs remain.
Constructions get their power from crossings, and a compass makes crossings faster than anything else: two circles of the same radius, struck from two points, cross at exactly the places a bisector or an equilateral triangle needs. The cost, on paper and in every drawing program, is that you end up with a page full of circles that were never part of the figure.
That is the clutter this tool removes. The crossings you marked stay live, tied to the real circles that produced them, so moving the original points moves every mark correctly. The circles simply stop being in the way.
Points that existed before you started belong to you and stay visible. A retired circle is still a live snap target, and Unhide All leaves these helper groups hidden on purpose, so a finished construction stays clean.
When you want a circle whose radius comes from something already in the drawing rather than from a rim point you click, use Compass: Radius instead: it transfers a length the way stepping a physical compass off a drawn segment does.
< Previous: Straightedge | Next: Compass: Radius >
- Compass & straightedge: the whole working method.
- Straightedge: the same two phases along a line.
- Compass: Radius: a construction circle sized from an existing object.