Thu Jul 4 19:12:39 EDT 2019

```Is the base of the whole arch structure (left side) supposed to be coplanar?
It doesn't look coplanar in your image.

Can you reduce the transition steps to 2 or 1 (I'm not sure how you are
counting so I don't know what is the minimum sensible option here).  The
point is to really push things to the minimal example that triggers your
problem, so that you can really inspect the example carefully---for example
look at every vertex coordinate in your polyhedron and every face list by
hand and see if you notice anything odd.

Are you generating this by using the skin() module from
list-comprehension-demos?

DanS wrote
> So I was taking your idea of doing less.  Instead of 105 transition steps
> I
> did 15.
> If I union it with a cube it only works if they don't touch at all, if
> they
> do touch it seems to blow up and render nothing.
>
> If I take the more simple version and do Preview -> Thrown together I
> don't
> see any pink / purple facets (but the edges are all pink purple) the one
> thing that strikes me as very odd is that each arch should be planar.  I
> would intuitively expect no triangles on the ends yet all the vertices on
> the ends are part of triangles.  Of course, it might also do those
> triangles if all the vertexes are planar, I just don't know.
>
> [image: image.png]
>
> On Thu, Jul 4, 2019 at 6:39 PM adrianv <

> avm4@

> > wrote:
>
>> DanS wrote
>> > yes, I've simplified it to where it seems to work.  So I know it breaks
>> > down where I do "wave" which interpolates between one curve and another
>> > using sin() (to give a smooth curve rather than a linear transition).
>>
>> Is it possible that you have very skinny facets showing up in pink
>> between
>> larger facets?   It just takes a single bad facet to ruin your entire
>> model.
>>
>> If the interpolation process is at fault can you use a simpler polygon as
>> the base for the interpolation?
>>
>>
>>
>>
>> --
>>
>> _______________________________________________
>>

>>
>
> _______________________________________________

>
>
> image.png (13K)