[OpenSCAD] How can I tell what OpenSCAD is doing?

nop head nop.head at gmail.com
Sun Oct 9 13:24:15 EDT 2016


Actually the version of OpenScad I use doesn't have an angle parameter so
they are full tori.

Linear extrude is fast because it doesn't use CGAL, but unioning anything
with lots of vertices is very slow.

To make a torus you need to just rotate flat sections of vertices and
connect them together with pairs of triangles to make the faces of the
tube. The rotation of the flat points takes care of the faces being bigger
further from the Z axis. See previous discussions about making 3D knots.

On 9 October 2016 at 18:05, nop head <nop.head at gmail.com> wrote:

> Yes they are only one degree slices of tori.
>
> On 9 October 2016 at 18:03, nop head <nop.head at gmail.com> wrote:
>
>> The only way to make things like that fast is to generate lists of
>> vertices and faces and pass them to polyhedron. GCAL is too slow to union
>> hundreds of objects.
>>
>> On 9 October 2016 at 18:00, Dan Shriver <tabbydan at gmail.com> wrote:
>>
>>> I want to make sure I understand your response.
>>>
>>> When you say "tori" you don't mean each is a torus, but each is a slice
>>> of a torus, right?
>>>
>>> I'm trying to make a torus of 360 slices, the goal being that if I can
>>> do that I can change each slice a little bit so the torus "morphs".
>>>
>>> I have been doing this kind of thing with linear_extrude() and am just
>>> doing a test here to make sure my approach with rotate_extrude() is correct.
>>>
>>> You are indicating that  it will be slow and painful the way I'm doing
>>> it.  Is there any way inside of OpenSCAD for me to make it faster (like
>>> rotate_extrude() does if it does the entire 360 itself) without decreasing
>>> the number of slices?
>>>
>>> On Sun, Oct 9, 2016 at 12:32 PM, nop head <nop.head at gmail.com> wrote:
>>>
>>>> The only thing you are asking CGAL to do is union 360 overlapping tori,
>>>> so that is what it will be trying to do. That will take a time approaching
>>>> infinity as union is very slow especially with overlapping shapes with lots
>>>> of vertices.
>>>>
>>>> On 9 October 2016 at 17:05, Dan Shriver <tabbydan at gmail.com> wrote:
>>>>
>>>>> I know this is is somewhat of a bad question (because CGAL is a black
>>>>> box...) but, even if the progress bar is a complete lie (which it usually
>>>>> is for me) is there some way that I can tell that openSCAD is still doing
>>>>> something and hasn't stopped?
>>>>>
>>>>> I ask because I have some simple test code:
>>>>>
>>>>> module testTorus() {
>>>>>   for (i = [0:360]) {
>>>>>     translate([(20*cos(i)),(20*sin(i)),0]) {
>>>>>       rotate_extrude(angle=1, convexity=10){
>>>>>         translate([20,20,0]) {
>>>>>           circle(r=10,$fn=5);
>>>>>         }
>>>>>       }
>>>>>     }
>>>>>   }
>>>>> }
>>>>>
>>>>> I ask it to run and I get "Rendering Polygon Mesh using CGAL..." and
>>>>> no other indication that things are progressing and just want to be sure it
>>>>> is still working.
>>>>>
>>>>> Why am I doing things this very painful way when I could just
>>>>> rotate_extrude through 360 degrees?  This is just a simple test case to see
>>>>> if what I am doing will work.  When I actually implement things I will have
>>>>> the different slices each be slightly different.
>>>>>
>>>>> _______________________________________________
>>>>> OpenSCAD mailing list
>>>>> Discuss at lists.openscad.org
>>>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>>>>
>>>>>
>>>>
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>>>>
>>>
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>>>
>>
>
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