[OpenSCAD] "Melting" models
arnholm at arnholm.org
arnholm at arnholm.org
Sat May 25 05:03:08 EDT 2019
On 2019-05-24 23:41, adrianv wrote:
> I suppose it's a somewhat advanced effort, but I don't think it would
> be
> particularly hard to write a "bent_sweep" module that would take a
> polygon
> expressed as a series of point coordinates and a second "destination"
> polygon also as a series of points. You could project the first
> polygon
> onto the second one and then build it up to the desired thickness (in
> the
> normal direction), constructing the vertices and faces of the necessary
> polyhedron.
A polygon in OpenSCAD is a 2d object with only (x,y) coordinates, so the
"destination" cannot exist anywhere but in the (x,y) plane. I think you
would "be on your own" having to write such from scratch using lists of
3d coordinates. Possible perhaps, but somewhat inconvenient. However,
sweeping is not the same as "melting" (or morphing rather). In a sweep
you start with a 2d shape and create a 3d object by sweeping the (rigid)
2d shape along a path to get a 3d object. OpenSCAD linear_extrude is a
special case of this. A slightly different case is
https://gist.github.com/arnholm/931bba4633ca344a3ffe0698b945395f
The melting/morphing case is quite different, it begins with an existing
valid 3d model created using any method. Usually keeping the topology of
the model fixed, the *shape* of the 3d model is modified. If the model
is represented as a polyhedron mesh, either explicitly modeled as such
or the result of mesh based boolean operations, changing the shape
translates to transforming the polyhedron vertex coordinates, using
different transformations for different vertices (i.e. "non-affine
transformation" of the model).
Carsten Arnholm
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