openscad + stl almost unusable?

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openscad + stl almost unusable?

juerg.maier
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Tried for many hours to get over CGAL problems. Tried to fix my stl with netfabb, meshlab and 123D but still run with every modification into CGAL problems. Rather frustrating. Why can't we have a proper CGAL compatibel STL export in OpenScad that does not cause a CGAL error when intersected, joined or differenced with basic shapes?
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Re: openscad + stl almost unusable?

ufomorace
What do you mean?

That the exported stl cannot reimport into openscad again?

Openscad only uses CGAL to make the STL, so if result is not compatible with input mesh of CGAL, it's an error in the CGAL which is coded by geometry professors.

I haven't had any stl that aren't fixed in netfabb, did you press the red + button? Don't know if the netfabb fixed CGAL result can be fed back into CGAL, you can also try meshmixer for boolean ops if you want to add smaller numbers of objects.

Openscads biggest strength is making printable STL using 1000ds of combined building blocks in super complex arrangements, perhaps the STL export re-import is just a weakness of CGAL engine.
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Re: openscad + stl almost unusable?

juerg.maier
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I ran into problems drilling curved pipes into an extruded polygon (OpenScad goes into an endless loop with F5). But I was able to create an .stl from it. However further processing of this stl causes CGAL errors when trying to difference() a cube out of it.
Tried many hours to get around this issue but whenever trying to combine 2 stl's or modify an existing .stl I get the CGAL error when trying to create the new stl.

Tried to fix stl's with netfabb, meshlab and meshmixer. These programs work fine but after reloading the stl's into OpenScad they still do not render.

Read also a lot about these issues and it all seems to come down that CGAL is rather difficult and picky. 123D print function looks like to have code that can create printable .stl's but OpenScad (which so far I loved to work with) gave me only headache.

If you are interested I can provide you with example files but as I said - it's rather frustrating and there seem to be no workarounds for the CGAL errors in OpenScad.
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Re: openscad + stl almost unusable?

donbright
If you would be willing to post some example .scad to http://github.com/openscad/openscad/issues it would likely be most helpful and appreciated. The simpler the example that exhibits the flaw, the more helpful.
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Re: openscad + stl almost unusable?

kintel
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In reply to this post by juerg.maier