Basket arch add-on updated to 2.83

A long time ago I wrote a small add-on to create a basket arch (a.k.a. three centered arch) in Blender.

There is now an updated version available in my GitHub repo that will run on Blender 2.83.

The user interface is slightly different (no more object layers) but the generated arch is the same.

Basket arch with given width and height

update: when using Blender 2.73 or later make sure you get the latest version (20150206 or newer) from GitHub.
In a previous article I showed a simple addon to create a basket arch with a given width. This update adds the possibility to set the height as well. A height of 0 will give you the classic basket arch and it will silently ignore width/height ratios > 4 or < 2 (in which case it will revert to a classic arch).

For width/height ratios close to 1.0 the fit isn't perfect and although I followed the instructions on ThisIsCarpentry.com (pdf) closely the curves for the classic arch and the one with known height are not exactly the same although to be honest I not 100% sure what to expect. It might also be due to numerical inaccuracies.

In the end you might be better of scaling the arch in the z-direction.

The previous article contains source code link and installation instructions.

Addon: Creating a basket arch in Blender: better symmetry

A slightly improved version of the addon is available on GitHub. It corrects the slight assymetry between the left and right sides (the bottom most vertices were not at the same height)

You can install it in the usual way: File->User preferences->Addons->Intall from file. Don't forget to check the 'enable addon' box. It will the be available from the Add Mesh menu in the 3D view.
If you already installed the first version do not forget to remove the old version firs: File->User preferences->Addons->Add Mesh->Basket arch->Remove



Addon: Creating a basket arch in Blender

Recently I was thinking about a visualization of some rooms in our house. These rooms were once separate but the wall has been broken through and the arch between them has a very specific form: a basket arch, aka three centered arch. This is a form widely used not only indoor but also for example for many 17th century bridges and is not entirely trivial to construct as it involves matching three circle segments at their tangents. So I constructed a small addon to create basket arches ;-)

Availability and possible improvements

The addon is available on GitHub. You can install it in the usual way: File->User preferences->Addons->Intall from file. Don't forget to check the 'enable addon' box. It will the be available from the Add Mesh menu in the 3D view.

The addon constructs what is called a classical three centered arch, that is you can only choose the width while the height has then a fixed proportion. It might be a good idea to add the variant where you can also specify the height, which will give a squeezed arch that is has not quite the same shape as a classical arch that is scaled in the z-direction.

Currently the vertices in the arch a distributed with more or less even spacing along the circle. Because we use the angle along a circle segment the last vertex may or may not touch the ground. This is however hardly visible and since I intended this addon for visualization rather than CAD I thought i good enough. I might fix it though in the near future.