Is there programmatic way to get the center (or any other reference, such as a corner) point of a 2d object at an arbitrary position in the XY plane? Mark

Its long time since I have written any function in openSCAD, but this should work p0=[[2,0],[10,5],[5,10]]; function center_point(p,p1=[0,0,0],n=0)= n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); echo(center_point(p0)); basically center of mass for any object would be sum of all the points(2d or 3d coordinates)/ number of points On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < discuss@lists.openscad.org> wrote: > Is there programmatic way to get the center (or any other reference, such > as a corner) point of a 2d object at an arbitrary position in the XY plane? > > Mark > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

Issue IS that in openscad you dont have Access to the objects vertices 😞 . Sanjeev Prabhakar via Discuss <discuss@lists.openscad.org> schrieb am Mo., 11. Nov. 2024, 17:22: > Its long time since I have written any function in openSCAD, but this > should work > > p0=[[2,0],[10,5],[5,10]]; > > function center_point(p,p1=[0,0,0],n=0)= > n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); > > echo(center_point(p0)); > > basically center of mass for any object would be > sum of all the points(2d or 3d coordinates)/ number of points > > On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < > discuss@lists.openscad.org> wrote: > >> Is there programmatic way to get the center (or any other reference, such >> as a corner) point of a 2d object at an arbitrary position in the XY plane? >> >> Mark >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

oh I thought to make a polygon in openSCAD you have to define points anyway. Nevermind, I wrote a recursive function after a long time in openSCAD On Mon, 11 Nov 2024 at 21:56, Guenther Sohler via Discuss < discuss@lists.openscad.org> wrote: > Issue IS that in openscad you dont have Access to the objects vertices 😞 > > . > > Sanjeev Prabhakar via Discuss <discuss@lists.openscad.org> schrieb am > Mo., 11. Nov. 2024, 17:22: > >> Its long time since I have written any function in openSCAD, but this >> should work >> >> p0=[[2,0],[10,5],[5,10]]; >> >> function center_point(p,p1=[0,0,0],n=0)= >> n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); >> >> echo(center_point(p0)); >> >> basically center of mass for any object would be >> sum of all the points(2d or 3d coordinates)/ number of points >> >> On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < >> discuss@lists.openscad.org> wrote: >> >>> Is there programmatic way to get the center (or any other reference, >>> such as a corner) point of a 2d object at an arbitrary position in the XY >>> plane? >>> >>> Mark >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email to discuss-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 to discuss-leave@lists.openscad.org >

 > oh I thought to make a polygon in openSCAD you have to define points anyway. To make a polygon primitive, yes. But you can also get 2D objects from Boolean combinations of other 2D objects, from projection(), from imported 2D objects, et cetera, and there’s currently no way to retrieve the coordinates of such an object. It’s exactly the same situation as for 3D objects, but flatter.

Use the 2d shape functions from BOSL2 which return geometry and you can manipulate it with their functions such as rotate, scale, union and difference which return geometry. BOSL2 also has functions such as path_closest_point() which you might use to find corners and calculate a center point. The BOSL2 code can also provide a starting point to modify into your own solutions when there isn't a routine in the library that can do what you need. On Mon, Nov 11, 2024 at 10:33 AM Sanjeev Prabhakar via Discuss < discuss@lists.openscad.org> wrote: > oh I thought to make a polygon in openSCAD you have to define points > anyway. > > Nevermind, I wrote a recursive function after a long time in openSCAD > > On Mon, 11 Nov 2024 at 21:56, Guenther Sohler via Discuss < > discuss@lists.openscad.org> wrote: > >> Issue IS that in openscad you dont have Access to the objects vertices 😞 >> >> . >> >> Sanjeev Prabhakar via Discuss <discuss@lists.openscad.org> schrieb am >> Mo., 11. Nov. 2024, 17:22: >> >>> Its long time since I have written any function in openSCAD, but this >>> should work >>> >>> p0=[[2,0],[10,5],[5,10]]; >>> >>> function center_point(p,p1=[0,0,0],n=0)= >>> n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); >>> >>> echo(center_point(p0)); >>> >>> basically center of mass for any object would be >>> sum of all the points(2d or 3d coordinates)/ number of points >>> >>> On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < >>> discuss@lists.openscad.org> wrote: >>> >>>> Is there programmatic way to get the center (or any other reference, >>>> such as a corner) point of a 2d object at an arbitrary position in the XY >>>> plane? >>>> >>>> Mark >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> To unsubscribe send an email to discuss-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 to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

I love it! <grin> On 11/11/2024 12:25 PM, Jordan Brown via Discuss wrote: > It’s exactly the same situation as for 3D objects, but flatter. > -- This email has been checked for viruses by AVG antivirus software. www.avg.com

I think maybe you meant to say that BOSL2 has functions that return point lists and you can manipulate them with rotate, scale, union, difference etc. In addition, BOSL2 has centroid() which computes the centroid (center of mass) of a polygon or polyhedron, which is not simply the average of the vertices. You can compute the average of the vertices---if you want that value instead---with mean(). On Mon, Nov 11, 2024 at 12:43 PM Todd Allen via Discuss < discuss@lists.openscad.org> wrote: > Use the 2d shape functions from BOSL2 which return geometry and you can > manipulate it with their functions such as rotate, scale, union and > difference which return geometry. BOSL2 also has functions such > as path_closest_point() which you might use to find corners and calculate a > center point. The BOSL2 code can also provide a starting point to modify > into your own solutions when there isn't a routine in the library that can > do what you need. > > On Mon, Nov 11, 2024 at 10:33 AM Sanjeev Prabhakar via Discuss < > discuss@lists.openscad.org> wrote: > >> oh I thought to make a polygon in openSCAD you have to define points >> anyway. >> >> Nevermind, I wrote a recursive function after a long time in openSCAD >> >> On Mon, 11 Nov 2024 at 21:56, Guenther Sohler via Discuss < >> discuss@lists.openscad.org> wrote: >> >>> Issue IS that in openscad you dont have Access to the objects vertices 😞 >>> >>> . >>> >>> Sanjeev Prabhakar via Discuss <discuss@lists.openscad.org> schrieb am >>> Mo., 11. Nov. 2024, 17:22: >>> >>>> Its long time since I have written any function in openSCAD, but this >>>> should work >>>> >>>> p0=[[2,0],[10,5],[5,10]]; >>>> >>>> function center_point(p,p1=[0,0,0],n=0)= >>>> n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); >>>> >>>> echo(center_point(p0)); >>>> >>>> basically center of mass for any object would be >>>> sum of all the points(2d or 3d coordinates)/ number of points >>>> >>>> On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < >>>> discuss@lists.openscad.org> wrote: >>>> >>>>> Is there programmatic way to get the center (or any other reference, >>>>> such as a corner) point of a 2d object at an arbitrary position in the XY >>>>> plane? >>>>> >>>>> Mark >>>>> _______________________________________________ >>>>> OpenSCAD mailing list >>>>> To unsubscribe send an email to discuss-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 to discuss-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 to discuss-leave@lists.openscad.org >

> I think maybe you meant to say that BOSL2 has functions that return point lists I said what I meant as I thought the point lists returned were one form of geometry and a VNF is another type of data representing geometry. The centroid() function which can operate on point lists and VNFs is in a file named geometry.scad. But if the word geometry is technically reserved for something else such as the output of rendering then thanks for the correction and explanation. On Mon, Nov 11, 2024 at 11:52 AM Adrian Mariano via Discuss < discuss@lists.openscad.org> wrote: > I think maybe you meant to say that BOSL2 has functions that return point > lists and you can manipulate them with rotate, scale, union, difference > etc. In addition, BOSL2 has centroid() which computes the centroid > (center of mass) of a polygon or polyhedron, which is not simply the > average of the vertices. You can compute the average of the vertices---if > you want that value instead---with mean(). > > On Mon, Nov 11, 2024 at 12:43 PM Todd Allen via Discuss < > discuss@lists.openscad.org> wrote: > >> Use the 2d shape functions from BOSL2 which return geometry and you can >> manipulate it with their functions such as rotate, scale, union and >> difference which return geometry. BOSL2 also has functions such >> as path_closest_point() which you might use to find corners and calculate a >> center point. The BOSL2 code can also provide a starting point to modify >> into your own solutions when there isn't a routine in the library that can >> do what you need. >> >> On Mon, Nov 11, 2024 at 10:33 AM Sanjeev Prabhakar via Discuss < >> discuss@lists.openscad.org> wrote: >> >>> oh I thought to make a polygon in openSCAD you have to define points >>> anyway. >>> >>> Nevermind, I wrote a recursive function after a long time in openSCAD >>> >>> On Mon, 11 Nov 2024 at 21:56, Guenther Sohler via Discuss < >>> discuss@lists.openscad.org> wrote: >>> >>>> Issue IS that in openscad you dont have Access to the objects vertices >>>> 😞 >>>> >>>> . >>>> >>>> Sanjeev Prabhakar via Discuss <discuss@lists.openscad.org> schrieb am >>>> Mo., 11. Nov. 2024, 17:22: >>>> >>>>> Its long time since I have written any function in openSCAD, but this >>>>> should work >>>>> >>>>> p0=[[2,0],[10,5],[5,10]]; >>>>> >>>>> function center_point(p,p1=[0,0,0],n=0)= >>>>> n==(len(p))?p1/len(p):center_point(p,p1+p[n],n+1); >>>>> >>>>> echo(center_point(p0)); >>>>> >>>>> basically center of mass for any object would be >>>>> sum of all the points(2d or 3d coordinates)/ number of points >>>>> >>>>> On Mon, 11 Nov 2024 at 21:16, Mark Erbaugh via Discuss < >>>>> discuss@lists.openscad.org> wrote: >>>>> >>>>>> Is there programmatic way to get the center (or any other reference, >>>>>> such as a corner) point of a 2d object at an arbitrary position in the XY >>>>>> plane? >>>>>> >>>>>> Mark >>>>>> _______________________________________________ >>>>>> OpenSCAD mailing list >>>>>> To unsubscribe send an email to discuss-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 to discuss-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 to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

Without getting feedback from cursor position, I'm not sure how you could define corners - 'top-left' wouldn't always work, for example. I expect, if you could define the point you wanted to select, you could just as easily calculate it in most cases. Openscad creates, it does not deconstruct. On 11/11/2024 15:46, Mark Erbaugh via Discuss wrote: > Is there programmatic way to get the center (or any other reference, such as a corner) point of a 2d object at an arbitrary position in the XY plane? > > Mark > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org