[OpenSCAD] STL without render?

bsuter ben.suter at gmail.com
Thu Jun 2 06:15:02 EDT 2016


Parkinbot wrote
> Can you share some image that shows your model in detail?

Sure, I'm attaching a view here.

CA3pyr-Amaral-c11571.png
<http://forum.openscad.org/file/n17523/CA3pyr-Amaral-c11571.png>  


Parkinbot wrote
> In OpenSCAD there are fast and slow alternatives to produce a design. If
> you stack too many primitives on top of each other, use boolean operations
> over too much detail (number of vertices) or special high-level operators
> like minkowski() and hull(), rendering gets slow. And it gets even slower,
> when you try to clone complex shapes into more complex structures like
> grids.

My model currently consists of a single sphere at the origin, and then about
1600 instances of a (tapered) cylinder with a sphere at the end (I add these
spheres where two non-parallel cylinders come together, to "fill out" the
join between them). I naively implemented each of these cylinder-sphere
pairs like this:

translate([-2.918, -7.452, 0.698])
rotate(93.4419, [0.800474,-0.596353,0])
cylinder($fn=20, 0.499704, 0.8, 0.5);
translate([-3.216, -7.852, 0.668])
sphere($fn=20, 0.5);

So the above 5 lines repeat roughly 1600 times, of course with different
values. The $fn values I chose basically to balance speed and beauty ...

As you can see in the image, this model is a naturally branched structure -
so for many of these cylinder-sphere segments, their translation and
rotation could naturally be defined as relative to their parent segment,
rather than using a flat structure with each segment oriented relative to
the origin (as I do now). Would you expect one of these approaches to be
faster?


Parkinbot wrote
> There are also ways to create complex shapes by doing most of triagulation
> work on your own. So it depends much on the programming approach you use
> and of course on the complexity of the design itself.

Interesting. Could you point me to some more info on the pre-triangulated
approach? I think I can maybe use Matlab (where I am analyzing the geometry
and generating the .scad now) to generate tessellated coordinates for each
cylinder, or at least the vertices.

Thank you very much!



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