arcs everywhere

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arcs everywhere

DanS
I have a project I want to work on which stalled out because I was having various problems with it.

I want to make some forms that use a lot of arches, and morphing arches from one into another.

Most of this would involve a simple gothic type arch (combination of two arcs) and ogee arch (combination of four arcs).  Typically I want to transition from one of these to the other.

Even though that should be very easy to do, I somehow kept getting tripped up by the math and having lots of unexpected problems.  For instance I wanted these two arch types to transition from one to another but I wanted the bottom of all the arches to be coplaniar (but I was having trouble with that).  Also I was doing the morphing by using tiny slices with linear_extrude and I seemed to have other issues because things weren't always coming out solid.

I would like to play with other arch types (parabolic, hyperbolic-catenoidal) but mainly the first two I described, and mainly various types of transitions from one into the other.

Additionally I would lay the arches along an odd path that is itself a group of arches.

Any suggestions?

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Re: arcs everywhere

DanS
I'd be interested in looking at your code.  And any suggestions by anyone else.

I think once someone suggested some module called something like "skins".

Any approaches to morphing are welcome...

On Fri, Aug 4, 2017 at 4:18 AM, Gadgetmind <[hidden email]> wrote:
On 04/08/17 03:05, Dan Shriver wrote:
I would like to play with other arch types (parabolic, hyperbolic-catenoidal) but mainly the first two I described, and mainly various types of transitions from one into the other.

Additionally I would lay the arches along an odd path that is itself a group of arches.

Any suggestions?

I'm sure there will be other ideas, but I'd represent the arches as vectors of points. You can generate these points algorithmically in functions (see the "let" operator as it's pretty much essential for complex functions), write additional functions to "tween" between two arches to generate new ones, and then render the arches as polygons to be extruded or hulled.

I use techniques like these to generate complex shapes based on things like wing profiles and super ellipses (generated by functions) that I then join together with splines to get the basic shapes, more splines at (roughly!) right angles to get a set of skin points, and then use "skin" from list comprehensions to create a 3D shape.

I've also done some conic sections by drawing cones (cylinders with one diameter set to zero) and using the project operator.

I can point you to my code on Thingiverse if you like, but I'm new to OpenSCAD and there are likely to be better ideas.



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