You will notice that the object in the STL in the previous message
 is actually not flat: it appears to be wrapped around the surface
 of a fairly large sphere (diameter 10" or 20"?).

 Are there any BOSL2 facilities that would take an object and warp
 it in this manner?  Since I have explicit 2D points lists, all I
 would really need to do is add a 3rd dimension I suppose.

 This is what I have at the moment:

 Then there is the question of how to make a shape with rounded
 edges that is also curved in this way (onto the sphere).

 Jon


 On 5/11/2024 10:29 AM, Jon Bondy via Discuss wrote:

 Maybe this non-manifold STL will help everyone envision the shape
 better.

 On 5/11/2024 8:42 AM, Adrian Mariano via Discuss wrote:

 Perhaps a better choice of glue could work?

 I don't understand your problem at all from the description.  To
 me it sounds like your challenge is creating the "lips", but I
 don't understand enough about the geometry to know how hard this
 is.  Like would sweeping a lip cross section along a planar
 curve work?  Or is the curve not planar (which creates twist
 issues)?  Or does the lip need to change across the sweep
 because the shape it's mating to changes?

 On Sat, May 11, 2024 at 8:24 AM Jon Bondy via Discuss
 <discuss@lists.openscad.org> wrote:

     Brainstorming, here...

     I have a car with paddle shifters (thin, flat metal plates
     with a curved
     periphery).  The car came with some paddle shifter
     "extensions" which
     sit behind the paddles (towards the front of the car, but
     "behind" the
     paddles from where I sit to drive). Think of the extensions
     as flat
     parts which are larger than the actual paddles, with a
     paddle-shaped
     indentation into which the paddles sit.  They are only
     attached with
     glue, and one came off the day I bought the car (used).  I
     tried to
     re-attach it with double-sided sticky tape, but that failed
     after a few
     weeks, so I am done with glue.

     What I want to do is 1) design a part that is identical to
     the original
     extension and then 2) add flexible "lips" to go around the
     paddle
     shifter to hold the extension in place.

     I can do (1) by photographing it and determining a series of
     points to
     specify the outer and inner shapes (1A).  This is easy to do
     approximately (and I have done so), but doing it accurately
     would take
     some time fiddling with the point list.

     I could also do (1) by scanning the part (also done) (1B).

     Although the above for (1) is a little challenging, the real
     challenge
     is how to create (2), the "lips" that wrap around the edge
     of the
     paddles to keep the extension in place.  The lips must curve
     around the
     inner shape (the one that defines the outside of the
     indentation).

     I imagine that scanning (1B) will solve (1) but not help at
     all with
     (2).  If I use the hand-crafted points approach (1B), then
     at least I
     have a defined curve around which I can sweep the lip
     cross-section.

     Any thoughts or comments?

     Thanks!

     Jon


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Looking at it carefully, I'll bet that a cylindrical wrap would suffice.  Can you point me to a way to do that with BOSL2? I take my original set of points and smooth them with "offset(-5) offset(5)", but the result is no longer accepted as input to path_extrude2d(): are there BOSL2 library functions to smooth my point list while still allowing the result to be used by path_extrude2d()? Thank you! Jon On 5/11/2024 12:17 PM, Adrian Mariano via Discuss wrote: > Taking a flat object and mapping it to a sphere is not a well-defined > operation.  BOSL2 does not provide a feature like this.  It can wrap > things around cylinders, but that *is* a well-defined process.  Think > about the problem of map projections.   If you want to map an object > to there sphere there will be multiple ways to do it depending on how > you distort your object in the mapping. > > But if you want to try the easiest thing and if you have your data as > points you can put it onto a sphere directly by computing z > coordinates that are on the sphere.  The simplest scheme would be to > just project it along the z axis onto a sphere, e.g. using the formula > z_warped = sqrt(r^2-x^2-y^2)+z. > > You can probably warp the lip this way if you make it using path_sweep > and get the VNF out and then warp the points component of the VNF.  > (The faces won't change.) > > On Sat, May 11, 2024 at 10:41 AM jon jonbondy.com > <http://jonbondy.com> via Discuss <discuss@lists.openscad.org> wrote: > > You will notice that the object in the STL in the previous message > is actually not flat: it appears to be wrapped around the surface > of a fairly large sphere (diameter 10" or 20"?). > > Are there any BOSL2 facilities that would take an object and warp > it in this manner?  Since I have explicit 2D points lists, all I > would really need to do is add a 3rd dimension I suppose. > > This is what I have at the moment: > > Then there is the question of how to make a shape with rounded > edges that is also curved in this way (onto the sphere). > > Jon > > > On 5/11/2024 10:29 AM, Jon Bondy via Discuss wrote: >> >> Maybe this non-manifold STL will help everyone envision the shape >> better. >> >> On 5/11/2024 8:42 AM, Adrian Mariano via Discuss wrote: >>> Perhaps a better choice of glue could work? >>> >>> I don't understand your problem at all from the description.  To >>> me it sounds like your challenge is creating the "lips", but I >>> don't understand enough about the geometry to know how hard this >>> is.  Like would sweeping a lip cross section along a planar >>> curve work?  Or is the curve not planar (which creates twist >>> issues)?  Or does the lip need to change across the sweep >>> because the shape it's mating to changes? >>> >>> On Sat, May 11, 2024 at 8:24 AM Jon Bondy via Discuss >>> <discuss@lists.openscad.org> wrote: >>> >>> Brainstorming, here... >>> >>> I have a car with paddle shifters (thin, flat metal plates >>> with a curved >>> periphery).  The car came with some paddle shifter >>> "extensions" which >>> sit behind the paddles (towards the front of the car, but >>> "behind" the >>> paddles from where I sit to drive). Think of the extensions >>> as flat >>> parts which are larger than the actual paddles, with a >>> paddle-shaped >>> indentation into which the paddles sit.  They are only >>> attached with >>> glue, and one came off the day I bought the car (used).  I >>> tried to >>> re-attach it with double-sided sticky tape, but that failed >>> after a few >>> weeks, so I am done with glue. >>> >>> What I want to do is 1) design a part that is identical to >>> the original >>> extension and then 2) add flexible "lips" to go around the >>> paddle >>> shifter to hold the extension in place. >>> >>> I can do (1) by photographing it and determining a series of >>> points to >>> specify the outer and inner shapes (1A).  This is easy to do >>> approximately (and I have done so), but doing it accurately >>> would take >>> some time fiddling with the point list. >>> >>> I could also do (1) by scanning the part (also done) (1B). >>> >>> Although the above for (1) is a little challenging, the real >>> challenge >>> is how to create (2), the "lips" that wrap around the edge >>> of the >>> paddles to keep the extension in place.  The lips must curve >>> around the >>> inner shape (the one that defines the outside of the >>> indentation). >>> >>> I imagine that scanning (1B) will solve (1) but not help at >>> all with >>> (2).  If I use the hand-crafted points approach (1B), then >>> at least I >>> have a defined curve around which I can sweep the lip >>> cross-section. >>> >>> Any thoughts or comments? >>> >>> Thanks! >>> >>> Jon >>> >>> >>> -- >>> This email has been checked for viruses by AVG antivirus >>> software. >>> www.avg.com <http://www.avg.com> >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>> >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email todiscuss-leave@lists.openscad.org >> >> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> >> Virus-free.www.avg.com >> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> >> >> >> >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email todiscuss-leave@lists.openscad.org > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email todiscuss-leave@lists.openscad.org -- This email has been checked for viruses by AVG antivirus software. www.avg.com