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    Method for drawing an antiprism with equilateral sides

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    sketchup
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    • TIGT Offline
      TIG Moderator
      last edited by

      Much easier ๐Ÿ˜’antiprism2d.PNG

      TIG

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      • S Offline
        sketchup_roolz
        last edited by

        Thanks Tig. You're a genius. ๐Ÿ˜Ž

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        • S Offline
          sketchup_roolz
          last edited by

          woops! ๐Ÿ˜ณ

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          • TIGT Offline
            TIG Moderator
            last edited by

            @sketchup_roolz said:

            Not that anyone cares anymore but here's a my proper 2D method...
            http://img573.imageshack.us/img573/272/68861221.png

            I fixed your faulty link...
            An interesting alternative approach... ๐Ÿ˜„
            I am thinking how it might get converted to an 'algorithm'...
            Which must be possible as it involves 45/30/15 degree triangles with known side length...
            Sleeping on it now... ๐Ÿ˜‰

            TIG

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            • S Offline
              sketchup_roolz
              last edited by

              Not that anyone cares anymore but here's a my proper 2D method...

              http://img573.imageshack.us/img573/272/68861221.png

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              • S Offline
                sketchup_roolz
                last edited by

                Very clever Jeff. ๐Ÿค“

                Much appreciation for all the hard work here.
                I don't really have a practical need to get this level of precision/accuracy but problems like this totally consume me.
                I figured the faster I could figure it out it the sooner I could move on to more important things! (or not)

                SketchUp is an amazing piece of software and maybe one day I'll have a more concrete use for it. ๐Ÿ’š

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                • pilouP Offline
                  pilou
                  last edited by

                  Why anybody save the SKP file "save as SU6"?
                  Like this anybody can reload easily any file! ๐Ÿ˜„

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

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                  • pilouP Offline
                    pilou
                    last edited by

                    PS :How many triangles must have the polyedra?
                    On the first post there are 8 on "the plan"
                    On the Xray Tig volume there are 7 ! ๐Ÿ˜ฎ

                    @unknownuser said:

                    Won't the file lose some of its v7, and v8 features. Did v6 have "dynamic components", etc.?

                    there are rarelly dynamic component in "hard geometry" like in this post or exotic functions ๐Ÿ˜„

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

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                    • honoluludesktopH Offline
                      honoluludesktop
                      last edited by

                      @unknownuser said:

                      Why anybody save the SKP file "save as SU6"?
                      Like this anybody can reload easily any file! ๐Ÿ™‚

                      Won't the file lose some of its v7, and v8 features. Did v6 have "dynamic components", etc.?

                      Btw, am I sticking my foot in my mouth? I didn't read all of the posts.

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                      • jeff hammondJ Offline
                        jeff hammond
                        last edited by

                        @unknownuser said:

                        Why anybody save the SKP file "save as SU6"?
                        Like this anybody can reload easily any file! ๐Ÿ˜„

                        oops, i try to remember to do this prior to uploading at scf but i just forget sometimes ๐Ÿ˜„
                        i added a v6 file to my earlier post

                        dotdotdot

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                        • honoluludesktopH Offline
                          honoluludesktop
                          last edited by

                          ???????????

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                          • honoluludesktopH Offline
                            honoluludesktop
                            last edited by

                            ???????????

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                            • jeff hammondJ Offline
                              jeff hammond
                              last edited by

                              here's another solution that allows rotating without the mega-segment arc..


                              antiprism.skp


                              same file.. saved as su6

                              dotdotdot

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                              • jeff hammondJ Offline
                                jeff hammond
                                last edited by

                                @unknownuser said:

                                PS :How many triangles must have the polyedra?
                                On the first post there are 8 on "the plan"
                                On the Xray Tig volume there are 7 ! ๐Ÿ˜ฎ

                                i don't think it matters.. here's an example using octagons with one of them rotated 22.5 degrees then using the same exact method i used for the squares.. resulting in 16 equal sides. (i think the people trying it though are using the wiki example which has 7 sides.)

                                edit -- lol. the wiki one, the one i drew, the one tig drew..etc have 8 sides hah ๐Ÿ˜ณ

                                octo.jpg

                                dotdotdot

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                                • TIGT Offline
                                  TIG Moderator
                                  last edited by

                                  @unknownuser said:

                                  PS :How many triangles must have the polyhedron?
                                  On the first post there are 8 on "the plan"
                                  On the Xray TIG volume there are 7 ! ๐Ÿ˜ฎ

                                  @unknownuser said:

                                  Won't the file lose some of its v7, and v8 features. Did v6 have "dynamic components", etc.?

                                  there are rarely dynamic component in "hard geometry" like in this post or exotic functions ๐Ÿ˜„

                                  In my Xray volume there are 8 triangles BUT the left-hand-most one is almost square to the camera ๐Ÿ˜’
                                  A very neat solution by Jeff BTW... ๐Ÿ˜„

                                  TIG

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                                  • TIGT Offline
                                    TIG Moderator
                                    last edited by

                                    If you think about it... as you increase the number of sides for the top and bottom faces the nearer they approximate the circles and the smaller the sides of the equilateral triangles forming the side facets so the 'height' decreases until with thousands of sides the top and bottom are approaching coplanarity...
                                    The simplest form has equilateral triangular faces, the next squares and so on.
                                    there are always twice as many sides as the edges to the faces: so the triangle solution has 3x2=6 sides, the square 4x2=8 sides and so on...

                                    TIG

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                                    • pilouP Offline
                                      pilou
                                      last edited by

                                      Ahhhh! I was victim of the perspective's law ๐Ÿ˜ณ ๐Ÿ’š

                                      hidden8.jpg

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

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                                      • pilouP Offline
                                        pilou
                                        last edited by

                                        Thx to Jeff for the "SU6 work" ๐Ÿ˜‰
                                        (you use unity of the old 20 century ๐Ÿ˜„
                                        And Chris Fullmer for his Component onto face ๐Ÿ˜„
                                        Now I can see all 8 triangles! ๐Ÿ’š
                                        The TIG's View was not good oriented! ๐Ÿ˜†
                                        8triangles.jpg

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

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                                        • TIGT Offline
                                          TIG Moderator
                                          last edited by

                                          To simplify things I have made a 'quick' Plugin - it's here http://forums.sketchucation.com/viewtopic.php?p=287140#p287140
                                          You just type into the Ruby Console:
                                          antiprism 7,1200.mm
                                          and it'll makes a 7 sided antiprism with sides 1200mm long, centered on the origin and grouped, named 'Antiprism[7x1200]'...
                                          You have to have at least 3 sides and a side-length > 0; the length is taken as inches if you haven't given a units suffix like 1.m or 100.cm or 1000.mm etc.
                                          The distance between faces changes with the number of sides as the maximum 'rake' on the side-triangle occurs at with 3 sides, and it proportionately decreases as the number of sides increases, until you approximate to a circle with a multi-sided polygon, and by then the side-triangles are almost vertical...

                                          TIG

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                                          • pilouP Offline
                                            pilou
                                            last edited by

                                            Else a very speedy method ๐Ÿ’š

                                            Draw Square A 1m * 1m (on the plan)
                                            Copy rotate Square A 45ยฐ = Square B (on the plan)
                                            Move Up Square B 1m on Z
                                            Draw the 8 segments between 8 vertices
                                            Select these 8 segments (method as you want)
                                            Scale on Z (Blue Scale oposite point) 0.840892091m (magical number) ๐Ÿ˜†
                                            Move down Square B vertical snaped a triangle vertice
                                            That's all ๐Ÿ’š

                                            And then you can resize at any size for any cubic antiprism with the Tape Mesure tool ๐Ÿ’š
                                            And all that without plugin, that is a real performance for me ๐Ÿ˜†

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

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