This is a library for generating "tube-like" meshes that join a number of cross-sections. For instance, one could use this for a wing profile, or a sphere, or thread.
The cross-sections don't have to planar, nor do they have to have the same number of points, but self-intersection of the resulting tube is likely to be a problem.
There is some optimization done to make triangles in the meshes be closer to equilateral.
One of the cool things one can do with this is "morph" between two plane shapes. For instance,
morphExtrude(ngonPoints(30,d=6), ngonPoints(2,d=4), height=10);
produces a wedge whose bottom is a circle of radius 3, and whose top is a line of length 4, while
morphExtrude([ [0,0], [20,0], [20,10], [0,10] ], [ [ 5,10 ] ], height=20 );
makes a pyramid with a rectangular base.
The main low-level API is the module
which takes a vector of three-dimensional counterclockwise cross-sections, and generates a polyhedron. The
optimize parameter controls triangle optimization. For smooth twisty things, you might want to increase it to 4 or 5, but for less smooth things, it might screw things up. If you are having problems, set it to 0 or 1.
There is also the higher-level module
This has two modes of operation. If
height is undefined, you feed it two three-dimensional sections (if you omit section2, it is the same as section1), and it interpolates between them to generate
numSlices layers. If
height is defined, you feed it two two-dimensional sections, and interpolation between the two sections separated by the specified
height is generated. The
twist is mainly for fun.
If you specify the
curve parameter, and
height is defined, then the interpolation parameter, which normally linearly changes from 0 to 1 with the z coordinate, is transformed according to the function specified by
curve. For instance, the pointy pyramid in the demo is done with:
morphExtrude([ [0,0], [20,0], [20,10], [0,10] ], [ [ 10,5 ] ], height=20, curve="sin(90*t)" );
You can use most of the standard OpenSCAD functions and operations for specifying the curve. See here for details. If you want to reference some parameters in your formula, you can add a
curveParams=[["paramA",valueA],["paramB",valueB],...] argument to
If you want access to the points and faces behind
pointsAndFaces() with the same arguments. This returns a
[points,faces] vector. In fact,
tubeMesh() is equivalent to calling
polyhedron() with the output of
As a demo, there is a
cone() module and a
mySphere() module. The latter has the same parameters as the built-in
sphere() primitive, but it uses a golden-angle spiral to generate a sphere whose triangles are more uniformly sized than those from the built-in module.
There are also some useful utility functions:
ngonPoints(n=4,r=10,d=undef,rotate=0,z=undef): generate the points of a regular
n-gon; 2D unless
z is specified
starPoints(n=10,r1=5,r2=10,rotate=0,z=undef): generate the points of a star; 2D unless
z is specified
roundedSquarePoints(size=[10,10],radius=2,z=undef): generate the points of a rounded square; 2D unless
z is specified
sectionZ(section,z): takes a list of 2D points and add a z-coordinate to them all
delta to every point in the
March 13, 2019: Better mesh optimization for smooth twisting things;
twist parameter reversed in direction to match
March 11, 2019: Can omit section2 parameter to
January 14, 2019: Works without the
eval.scad library if you don't use the curve parameter. There will be some warnings, but they can be ignored.
November 18, 2018: Added
curve parameter to
November 21, 2017: Added
September 17, 2017: Added
tubeMesh() module for convenience.