So I rewrote my spring module as a function that returns a mesh (points and
faces) so I can save it as a variable and then re-use it to draw many
springs by simply calling polyhedron.

100 springs was taking 61 seconds when it was doing a sweep for each one.
With only one sweep to generate the mesh and 100 calls of polygon it now
takes 23 seconds. Why is polyhedron so slow? I expected it to by
instantaneous in F5. All it has to do is process the lists into a polyset.

On Tue, 22 Jan 2019 at 23:35, Parkinbot rudolf@digitaldocument.de wrote:

But OpenSCAD's Polyset class is just a polygon soup, so no better than STL
and suffers all the same problems as far as I can see. You have to sort
anything out to make one from a polyhedron, just convert the face lists to
polygons by indexing the points. You are actually going from a more
structured data format to a less complicated one. I think it is only if you
want to use it with CGAL that a more complicated data structure is used,
I.e. Nef_Polyhedron. For an F5 preview a PolySet should be all you need. It
needs to be triangulated but I have already done that for all but the
endcaps.

The code is here:
https://github.com/openscad/openscad/blob/69bf5a55475102be43c2ddc698198e85821332b3/src/primitives.cc#L552
I don't see anything that would take any time on a modern PC that runs at
GHz.

On Sat, 26 Jan 2019 at 13:08, Parkinbot rudolf@digitaldocument.de wrote:

Is it perhaps that the lists are stored as strings when the polyhedron is
instantiated and then parsed to vectors every time the geometry is created.

Would converting them to vectors of doubles in PrimitiveModule::instantiate
make it faster or is that called 100 times as well?

On Sat, 26 Jan 2019 at 17:33, nop head nop.head@gmail.com wrote:

nophead wrote

I doubt that. But you are right, the code really looks like nothing very
time consuming is happening.
Is the triangulation of the faces done by Open GL? What happens after the
geometry has been created?

--
Sent from: http://forum.openscad.org/

It spends most of the 22 seconds stuck at Compiling design (CSG Tree
generation)...

After that it does all the rest in about 1 second, including a very fast
progress bar.

Compiling design (CSG Products generation)...

Geometries in cache: 395

Geometry cache size in bytes: 20331104

CGAL Polyhedrons in cache: 0

CGAL cache size in bytes: 0

Compiling design (CSG Products normalization)...

Normalized CSG tree has 100 elements

Compile and preview finished.

Total rendering time: 0 hours, 0 minutes, 22 seconds

It would be a problem if I was designing a mattress with PLA springs but
fortunately only a battery box with four, but it would be nice if
polyhedrons were cached like other geometry seems to be. I clearly don't
fully understand OpenSCADs caching system.

On Sun, 27 Jan 2019 at 22:33, Parkinbot rudolf@digitaldocument.de wrote:

Hi nophead,

Could you post a sample script for others to reproduce the slowness you
experience?

Thanks,
Hans

On Sun, Jan 27, 2019 at 4:59 PM nop head nop.head@gmail.com wrote:

Here is a boiled down version:
https://gist.github.com/nophead/fd4ca58b5f6b19dc25bb98f7edbae90f

I captured the points and face lists generated by sweep and hard coded them
to remove all of my library. Each spring is 4576 points, 9122 faces but
they are all the same polyhedron repeated 100 times. Given that it doesn't
cache polyhedra it has to process the same lists to a Polyset 100 times.
Taking about 1/4 second to process 9000 faces seems very slow to me on a 64
bit 2.5GHz core I7 with 8 GB memory.

On Mon, 28 Jan 2019 at 02:23, Hans L thehans@gmail.com wrote: