divider or compass tool - or equivalent way - in Inkscape or Gimp?

Question

Is there a divider or compass tool in Inkscape or Gimp?

What I mean is the drafting tool called a divider is a way to scribe an arc a fixed distance from a point. The compass does this also. I naturally searched for this tool in Inkscape and Gimp and gathered that no such direct tool exists.

So I am also interested to know how an equivalent operation can be carried out in perhaps Inkscape, just like with a compass :

1. fix compass leg on a point
2. draw an arc or circle a fixed distance from the rotation point
3. move compass leg to a new rotation point
4. draw new arc [ repeat ]

... otherwise, it seems that the only way to do that would be manually measure from a point, make a line, then get the circle/ellipse tool and draw a circle, adjust the circle to be a specified diameter. In particular, the intersections of these arcs will not be known in advance.

Or, perhaps, this is more suited as a computational or scripting task - which perhaps Inkscape or Gimp can handle, but I have not looked into yet.

Answer 1

I think you may be overthinking this slightly and reflecting a bit too much on traditional tools.

Using vector drawing software, such as Inkscape, it's a simple matter to draw a circle at a desired diameter, or change the diameter after a circle has been drawn.

In addition, it's easy to position the center point of any circle, or even draw a specified diameter from a specified center point.

The "Circle" or "Ellipse" tool is all that is generally required. These tools essentially replace any "compass" or "divider" tool.

The old-world method of using a compass is completely irrelevant for digital creation. Both the diameter and center position can be precisely set for any circle before or after it has been drawn in software.

_{(I can't speak for GIMP.... I have no experience with it, but GIMP is a raster image editor, unlike the vector editor which is Inkscape.)}

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If you are looking to animate a circle creation similar to how one would "pull" a circle by hand with a compass, that's an entirely different matter.

Answer 2

I found an approach that works / is better than nothing, to get the idea across - the "real world" idea of using a compass or dividers to scribe circles from a set of points, but in Inkscape. I have to assume some Inkscape knowledge for this. It is simple, but takes some writing, and I am not up to speed with posting images yet.

1. make a shape, perhaps a freehand line.
2. add some nodes using Ctrl-Alt-click to the shape above. Please note the picture might have lost a few nodes after the circles were put in - that is, n circles != n nodes.
3. make a circle, perhaps with a different color.
4. snapping/toggle settings - on the vertical tool bar on the user's right. only "on" settings are listed for this. here, ".." means "toggle snapping" :

.. on/off

.. to nodes (global)

.. to smooth nodes, including quadrant points of ellipses

.. to misc. points (global)

.. to object rotation center

using a mouse/trackpad, move the circle so the circle center snaps to the node you want. Ctrl-V the same circle out, repeat the process for the next node, and so on. This produces a set of circles all of the same diameter all overlapping but with their centers following the path of the nodes.

That is only to describe the way to "use dividers or a compass", but in the way Inkscape requires. It would be great to refine this, but perhaps in separate, specific posts.

UPDATE: This post gives an idea how to calculate coordinates of circles to line up on points that were calculated to lie on a curve.

Answer 3

In Gimp you can use the Measure tool:

• Click on the "center"
• Drag out, watching the lenght/angle in the status bar (if you depress "Control" while doing so you are constrained to multiples of 15°)
• When reaching a point, release mouse button
• Depress Alt+Ctrl and click down, to create two guides that intersect on the point.

But usually you will get a full circle and then remove the parts you don't want (edit the path, or use the intersection/subtraction operations on a selection).