tick and strike

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CLI

Tick and strike

The straightedge and the compass from the command line. Two commands, model tick and model strike, and the host you name decides which form you get.

Important

Under construction. The CLI is being built, and this page describes work in progress. What it is called, what it can do, and how it behaves are all still moving. Nothing here is a promise about the finished feature.

One command, two forms

Both commands name the host they work on, and the kind of host decides the result. A line host gives you the straightedge form, a circle host the compass form. That is why there is one command for each rather than two.

Both also take points, not coordinates. Place the point first, either as a point that slides along the host or as the crossing of two objects, then name it.

• Point: On Object: a point that slides along a segment, line, arc or circle.
• Points: Intersection: a point where two objects cross.

A tick is the short mark

A tick lies along its host, not across it. This is the thing most readers assume the other way around. On a line host it is a short segment on the same line, and on a circle host it is a short arc of that same circle. Either way it is centered on the point you name.

On a straight host

model tick \
  --host "sideAB" \
  --at "touchAB" \
  --name "tickAB"

A short segment sitting on sideAB, centered on touchAB, running the same direction as the line.

On a circle host

model tick \
  --host "incircle" \
  --at "touchAB" \
  --name "tickRim"

A short arc of incircle, centered on touchAB, curving with the circle.

How long it is

A tick is 4 mm unless you say otherwise, and --len says otherwise:

model tick \
  --host "sideAB" \
  --at "touchAB" \
  --len 8 \
  --name "tickLong"

The default is not written into the command. It comes from the tick length preference, which has one setting for straightedge (line) ticks and one for compass (arc) ticks, so the host kind picks which one applies. It is the same setting the Straightedge and Compass tools read, which means a command and a drag by hand give you the same length.

A strike is the piece you keep

A strike is the part of the line or circle you actually drew. It takes two points on the host, and both ends stay points on the host, so the strike follows the construction when a parent point moves. It also remembers which host it ran along.

On a straight host

model strike \
  --host "sideAB" \
  --from "cornerA" \
  --to "touchAB" \
  --name "strikeAB"

On a circle host

model strike \
  --host "incircle" \
  --from "touchAB" \
  --to "touchBC" \
  --name "arcRim"

A strike on a circle takes that circle's own center, so its radius is the compass opening it was drawn with. There is nothing to keep in sync: change the circle and the strike follows.

Related

• Compass & straightedge construction: the same two marks drawn by hand, in the modeling window.
• CLI commands: the commands, what each takes, and what it does.
• Tangent circles: a construction worked all the way through.
• Preferences: where the default tick lengths live.

< Previous: Tangent circles | Next: Making regions >