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    Geosphere?

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    • thomthomT Offline
      thomthom
      last edited by

      Best I can find is: http://en.nicoptere.net/?p=12 - actionscript based on this: http://www.math.niu.edu/~rusin/known-math/96/repulsion
      But I'm not making a whole lot sense out of it. The code doesn't have much commenting...

      Thomas Thomassen — SketchUp Monkey & Coding addict
      List of my plugins and link to the CookieWare fund

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      • pilouP Offline
        pilou
        last edited by

        A sphere with a center (x0,y0,z0) with diameter r
        has all points x,y,z like

        http://upload.wikimedia.org/math/3/3/0/33031c82e871501422b05455c81d2680.png

        with

        http://upload.wikimedia.org/math/e/b/9/eb91f8174391d023015dedf9beb94e5d.png

        http://upload.wikimedia.org/math/9/0/1/9011474548ae3216019a280ff95d25a3.png
        = Latitude

        http://upload.wikimedia.org/math/1/9/6/1964adc54d7dc608fd9f63a46cae422b.png
        = longitude

        Frenchy Pilou
        Is beautiful that please without concept!
        My Little site :)

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        • thomthomT Offline
          thomthom
          last edited by

          Isn't that a sphere with poles? The points would not be evenly spaced.

          sphere.png
          I'm looking to generate the points for the sphere on the right.

          Thomas Thomassen — SketchUp Monkey & Coding addict
          List of my plugins and link to the CookieWare fund

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          • T Offline
            tml
            last edited by

            @thomthom said:

            I'm looking to generate the points for the sphere on the right.

            Start with a octahedron, divide each edge into half and thus each face into four equal smaller triangles, move the new vertices to the desired radius, repeat.

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            • T Offline
              tml
              last edited by

              Note that the above results in just a fairly nice approximation, though. (And I don't know if it matches the subdivision used in your example image.) Only for the (not really sphere-like, as they have so few faces) Platonic solids are the vertices in a strict sense evenly distributed, though. See http://www.cgafaq.info/wiki/Evenly_distributed_points_on_sphere and especially http://www.math.niu.edu/~rusin/known-math/95/sphere.faq .

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              • thomthomT Offline
                thomthom
                last edited by

                Approximation is ok. Just just want to take a fixed number of points and distribute them approximately evenly. Doesn't matter if they need to be rounded to a number that fit some geometric restriction.

                Thanks for the links - I'll look into them.

                Thomas Thomassen — SketchUp Monkey & Coding addict
                List of my plugins and link to the CookieWare fund

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                • thomthomT Offline
                  thomthom
                  last edited by

                  Excellent - the spiral methods works great for my use! 👍

                  Thomas Thomassen — SketchUp Monkey & Coding addict
                  List of my plugins and link to the CookieWare fund

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                  • AdamBA Offline
                    AdamB
                    last edited by

                    Its pretty common to subdivide a cube and then project onto a sphere.

                    If you want evenly distributed but not a regular mesh, you could use a Hammersley point set.

                    Developer of LightUp Click for website

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                    • thomthomT Offline
                      thomthom
                      last edited by

                      @adamb said:

                      Its pretty common to subdivide a cube and then project onto a sphere.

                      Would that give a even-ish distribution?

                      @adamb said:

                      If you want evenly distributed but not a regular mesh, you could use a Hammersley point set.

                      Thanks for the pointer - will look it up. 👍

                      Thomas Thomassen — SketchUp Monkey & Coding addict
                      List of my plugins and link to the CookieWare fund

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                      • david_hD Offline
                        david_h
                        last edited by

                        @unknownuser said:

                        A sphere with a center (x0,y0,z0) with diameter r
                        has all points x,y,z like

                        http://upload.wikimedia.org/math/3/3/0/33031c82e871501422b05455c81d2680.png

                        with

                        http://upload.wikimedia.org/math/e/b/9/eb91f8174391d023015dedf9beb94e5d.png

                        http://upload.wikimedia.org/math/9/0/1/9011474548ae3216019a280ff95d25a3.png
                        = Latitude

                        http://upload.wikimedia.org/math/1/9/6/1964adc54d7dc608fd9f63a46cae422b.png
                        = longitude

                        That is just how I would do it! 😒 💚

                        If I make it look easy...It is probably easy

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                        • pilouP Offline
                          pilou
                          last edited by

                          Me too 😄

                          Frenchy Pilou
                          Is beautiful that please without concept!
                          My Little site :)

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                          • thomthomT Offline
                            thomthom
                            last edited by

                            Google are really quick to index this site!
                            I did a search for "Hammersley point set sphere" and this thread came up as #3 already. 😒

                            Thomas Thomassen — SketchUp Monkey & Coding addict
                            List of my plugins and link to the CookieWare fund

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                            • mitcorbM Offline
                              mitcorb
                              last edited by

                              Not busy enough elsewhere, eh tml?
                              Thank you for your talents, also.

                              I take the slow, deliberate approach in my aimless wandering.

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                              • AdamBA Offline
                                AdamB
                                last edited by

                                There you go.

                                http://forums.sketchucation.com/viewtopic.php?f=180&t=30694&p=269864#p269864

                                Developer of LightUp Click for website

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