Revolve2 OpenSCAD library module

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**Better Stability, Clarity, and Added Functionalities** If you loved Revolve, you'll adore Revolve2! **Introduction** This OpenSCAD module empowers rotational extrusion of generic user-defined profiles with a pitch in the longitudinal direction, perfect for creating screws and other threaded objects. The solid is constructed as a single polyhedron by transforming 2D points found in the profile vector, ensuring optimal performance through minimal object complexity. **Arguments** ``` revolve(profile = [[]], length, nthreads=1, scale=1, preserve_thread_depth=false, preserve_thread_shape=false, $fn=$fn, force_alternate_construction=false) ``` * `profile`: A vector of 2D points defined as [[z_1, f(z_1)], [z_2, f(z_2)] ... [z_n,f(z_n)]]. * f(z) is a function that describes the shape of the thread without any restrictions, allowing for dovetail-like profiles and even square profiles with shared points. * The shape can be refined by adding more points. A `linspace` helper function can be used to create the profile from a mathematical function (see example below). * `length`: Determines how far in the longitudinal direction to go, with mesh size increasing linearly with this parameter. * `nthreads`: Allows for creating screws with multiple threads, taking an integer value. Negative values generate left threads, and `nthreads=0` results in no pitch, similar to `rotate_extrude`. * `scale`: Enables scaling in the longitudinal direction, making top faces scale-times larger than bottom ones. This parameter accepts a scalar value between 0 and infinity. * `preserve_thread_depth`: Preserves the depth of the thread, which may otherwise be "flattened." Useful only if `scale!=1`. * `preserve_thread_shape`: Preserves the shape of the thread when `true`, overriding `preserve_thread_depth`. Only useful if `scale!=1`. * `$fn`: Controls the number of subdivisions in the angular direction, similar to `$fn` for a cylinder. In the longitudinal direction, the number of subdivisions is controlled by the profile's point count. * `force_alternate_construction`: Forces alternate construction for proper cutting of top and bottom faces when they intercept threads. **Example** ``` // The simplest possible example: revolve(profile=[[0,5],[1,6],[2,5]], length=10, nthreads=1, $fn=8); // Now going a bit wilder // Define a sinusoidal profile function... period = 3; function prof_sin(z) = [z, 10+sin(z*360/period)]; // ...which becomes a profile vector with the help of linspace sin_prof = [for (z=linspace(start=0, stop=period, n=15)) prof_sin(z)]; translate([30,0,0])revolve( sin_prof, length=20, nthreads=-5, $fn=30); // Using the scale functionality // A square profile defined manually sqr_prof = [[0,11],[2,11],[2,9],[4,9],[4,11]]; intersection() { translate([-20,10,-10]) cube([20,100,50]); union () { color("red") translate([0,30]) revolve( sqr_prof, length=30, scale=0.2, nthreads=-1, $fn=30); color("blue") translate([0,60]) revolve( sqr_prof, length=30, scale=0.2, preserve_thread_depth=true, nthreads=-1, $fn=30); color("green") translate([0,90]) revolve( sqr_prof, length=30, scale=0.2, preserve_thread_shape=true, nthreads=-1, $fn=30); } } // To reproduce the sample STL: // revolve_demo_scene(); ``` **License** This OpenSCAD module was written by Dario Pellegrini (`pellegrini dot dario at gmail dot com`). It is released under the Creative Commons Attribution (CC BY) license v4.0 or later, available at https://creativecommons.org/licenses/by/4.0/. **Changelog** * 2018/11/14 Released v2.0 - Code almost entirely rewritten for better clarity, stability, performance, and added functionalities. * 2018/11/09 Released v1.0