I am unclear why this code results in a pristine cylindrical extrusion EXCEPT for one small place where it seems to twist frantically... include <sweep.scad> function f(a) = [18*sin(360*a), 18-18*cos(360*a*0.7), 36*sin(360*a/2)]; function shape(d) = let (dd = 5 * (1.2 - d/steps))     [for (i=[1:10:360]) [dd*sin(i), dd*cos(i)]]; step = 0.005; steps = 1/step; path = [for (t=[step:step:1-step]) f(t)]; path_transforms = construct_transform_path(path); sweep(shape(1), path_transforms); -- Sent from my desktop computer. I do not receive emails while away from my desk, nor do I receive texts on my main phone number (which is a land line). If you know that I am on the road, please text me. If you know that I am home, please email me.

@jon The original sweep.scad may show wild twists when the path gets a vertical (along z) step. This is discussed in http://forum.openscad.org/Twisty-problem-with-scad-utils-quot-sweep-quot-tc9775.html. There you will find also change suggestions to overcome that behavior. I have implemented those suggestions in a fork of sweep.scad and the results are far better. You may find my fork in https://github.com/RonaldoCMP/list-comprehension-demos. 2018-01-05 12:55 GMT-02:00 jon <jon@jonbondy.com>: > I am unclear why this code results in a pristine cylindrical extrusion > EXCEPT for one small place where it seems to twist frantically... > > > > include <sweep.scad> > > function f(a) = [18*sin(360*a), 18-18*cos(360*a*0.7), 36*sin(360*a/2)]; > > function shape(d) = let (dd = 5 * (1.2 - d/steps)) > [for (i=[1:10:360]) [dd*sin(i), dd*cos(i)]]; > > step = 0.005; > steps = 1/step; > path = [for (t=[step:step:1-step]) f(t)]; > path_transforms = construct_transform_path(path); > sweep(shape(1), path_transforms); > > > > -- > Sent from my desktop computer. > I do not receive emails while away from my desk, > nor do I receive texts on my main phone number > (which is a land line). > If you know that I am on the road, please text me. > If you know that I am home, please email me. > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

 I am unclear why this code results in a pristine cylindrical
 extrusion EXCEPT for one small place where it seems to twist
 frantically...



 include <sweep.scad>

 function f(a) = [18*sin(360*a), 18-18*cos(360*a*0.7),    
 36*sin(360*a/2)];

 function shape(d) = let (dd = 5 * (1.2 - d/steps))
     [for (i=[1:10:360]) [dd*sin(i), dd*cos(i)]];

 step = 0.005;
 steps = 1/step;
 path = [for (t=[step:step:1-step]) f(t)];
 path_transforms = construct_transform_path(path);
 sweep(shape(1), path_transforms);



 -- 
 Sent from my desktop computer.
 I do not receive emails while away from my desk,
 nor do I receive texts on my main phone number
 (which is a land line).
 If you know that I am on the road, please text me.
 If you know that I am home, please email me.


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 Discuss@lists.openscad.org <mailto:Discuss@lists.openscad.org>
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 <http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org>

Thank you for recalling the thread so clearly!  Very helpful.  I did notice more than one "sweep.scad" on my computer, but was not able to recall why I should use one over the other. Jon On 1/5/2018 10:05 AM, Ronaldo Persiano wrote: > @jon The original sweep.scad may show wild twists when the path gets a > vertical (along z) step. This is discussed in > http://forum.openscad.org/Twisty-problem-with-scad-utils-quot-sweep-quot-tc9775.html. > There you will find also change suggestions to overcome that behavior. > I have implemented those suggestions in a fork of sweep.scad and the > results are far better. You may find my fork in > https://github.com/RonaldoCMP/list-comprehension-demos. > > 2018-01-05 12:55 GMT-02:00 jon <jon@jonbondy.com > <mailto:jon@jonbondy.com>>: > > I am unclear why this code results in a pristine cylindrical > extrusion EXCEPT for one small place where it seems to twist > frantically... > > > > include <sweep.scad> > > function f(a) = [18*sin(360*a), 18-18*cos(360*a*0.7),     > 36*sin(360*a/2)]; > > function shape(d) = let (dd = 5 * (1.2 - d/steps)) >     [for (i=[1:10:360]) [dd*sin(i), dd*cos(i)]]; > > step = 0.005; > steps = 1/step; > path = [for (t=[step:step:1-step]) f(t)]; > path_transforms = construct_transform_path(path); > sweep(shape(1), path_transforms); > > > > -- > Sent from my desktop computer. > I do not receive emails while away from my desk, > nor do I receive texts on my main phone number > (which is a land line). > If you know that I am on the road, please text me. > If you know that I am home, please email me. > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org <mailto:Discuss@lists.openscad.org> > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > <http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org> > > > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org -- Sent from my desktop computer. I do not receive emails while away from my desk, nor do I receive texts on my main phone number (which is a land line). If you know that I am on the road, please text me. If you know that I am home, please email me.