error messages with 0penscad generated stl's.
When you do F5 before F6 some intermediate results are cached as PolySets,
which can break the topology and then they get fed to CGAL when you do F6
and it complains. If you flush the cache before F6 all the processing is
done by CGAL without intermediate PolySet conversion and it works.
On Sun, 9 Oct 2022 at 11:52, Ray West raywest@raywest.com wrote:
I tried again, the next morning, and it imported fine. This was in a new
instance of openscad. It has been pointed out to me to 'flush the cache'.
Starting afresh does that, of course.
So, it seems that objects generated and exported by openscad can be
imported and manipulated, which was as I had expected provided I remember
to flush the cache, if it's towards the end of a lengthy session.
However, repeating the situation a number of times, I expect it could be
like photocopying photocopies - either ends up all black or all white.
On 06/10/2022 22:22, Raymond West wrote:
Thanks,
If, maybe, sometimes. Not the sort of thing to be relied on, then.
In further testing, it works as I expected with cylinders or cubes, even
offsetting the translates by tiny amounts. But whatever triangles in the
stl are generated, they would be few and relatively large.
The cat was something I knocked together very quickly, just half a dozen
cylinders, a cone and a distorted sphere to represent the head, to show my
granddaughter. Now the cone and head would have small triangles where they
merge. I'll cut the head off, I expect it will render. (maybe reducing $fn
would sort it, too.)
It is not so much a problem, if the problem can be defined. It is annoying
when things/methods that have worked well before, come unstuck because of
some unknown factor
Best wishes,
Ray
PS I dismembered the cat, It still didn't work. I've attached the scad
file, which 'as is' will make a number of cylinders. If that is exported as
an stl named 'cats.stl', then you can run
module cats(){
import("P:/Docs/openscad/cats.stl"); //? your file
}
cats();
translate([500,0,0])cats();
as I mentioned before and it will not f6 for me. I may find out the
simplest stl that will not f6 when imported and translated.
Still doesn't solve my original lithopane quest, however.
Best wishes,
Ray
On 06/10/2022 21:29, Jordan Brown wrote:
There are two components to your problem.
- OpenSCAD doesn't always like to import its own output.
Not much that I can say about this. It seems pretty wrong, but I am sure
there are reasons why fixing it is hard. I haven't looked.
- OpenSCAD's behavior in the face of importing STLs that it does not
like is ... strange.
If you have an STL (or, for that matter, a polyhedron()) that isn't quite
right, OpenSCAD will do one of three things:
- F5 - will probably work, because it doesn't actually analyze the
geometry.
- F6 of the troublesome object alone - will probably work, because
analyzing the geometry is somehow optimized away.
- F6 of the troublesome object in conjunction with anything else -
analyzes the geometry and fails.
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