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[Plugin] Cyma Curve Tool

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  • T Offline
    TIG Moderator
    last edited by 7 Mar 2010, 20:47

    This Tool makes a classical 'Cyma' curve - see below for details...

    Copyright 2010 (c) TIG
    All Rights Reserved.
    THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
    WARRANTIES,INCLUDING,WITHOUT LIMITATION,THE IMPLIED WARRANTIES OF
    MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

    CymaCurveTool.rb

    Usage:
    Choose 'Cyma Curve Tool' from the Plugins Menu;
    or type 'cyma' in the Ruby Console...

    Select parameters in the dialog, on OK the specified Cyma Curve
    appears on the end of your cursor - place it where you wish...
    The parameters are:
    Overall Size X: The Horizontal size of the enclosing square -
    default 100mm or 4" depending on model's units,
    the last entered value is remembered with the model.
    Overall Size Y: The Vertical size of the enclosing square -
    default 100mm or 4" depending on model's units,
    the last entered value is remembered with the model.
    Chord Proportion:
    The proportion of the Curve's Arc's Chord to its Radius.
    There are two possibilities...
    1: assuming a 'square form' [X==Y]...
    For a basic Cyma it's sqrt(2) [1.4142136]
    giving tangential springing points [90 degree].
    For a "Palladian" Cyma it's 7/6 [1.1666666]
    giving flattened arcs to the curve [the default].
    The smaller the value the flatter the arcs, so 1 gives
    equilateral arcs which can look too flat when viewed
    from below; values <0.1 will given arcs so flat you
    could have used straight lines! so 0.1 is the minimum.
    You can enter values in decimal format [1.2345],
    fractional format [7/6] or as 'sqrt' [sqrt(2)]
    [note format with (nn) etc]
    2: assuming a 'rectangular' form [X!=Y] the 90 degree
    'tangential' form can be set by giving the
    Chord to Radius proportion based on the formula
    2Y/sqrt(XX+Y*Y)
    so you can calculate this beforehand and enter it as
    a decimal value, e.g. it's 0.8944 when X=200 & Y=100,
    OR as it's also shown in the VCB prompt once the X & Y
    values are set: to get it calculated for you, you make
    a rectangular Cyma using the default value and then
    immediately undo it, then rerun the tool - all of the
    dialog's values are remembered, but the VCB prompt now
    also shows the value that would give a tangential
    90 degree form - so you can type that value into the
    dialog and get 90 degree tangential springing points
    for rectangular forms too.
    Otherwise you can use the 7/6 or other values as
    desired...
    Curve Type: The two types of curve available are:
    'Cyma Recta' - also called 'Gola'
    [starts convex, ends concave] - it is the default type.
    and
    'Cyma Reversa' - also called 'Ogee'
    [starts concave, ends convex]
    Curve Format: You choose from the following:
    'As Curve' - just the two arcs welded as a curve.
    'As Curve with Face' - the two arcs welded as a curve
    and their internal edges with a face -
    useful for extrusions.
    'As Curve with Guides' - the two arcs welded as a curve
    with guide-lines and -points added to show the
    arcs' centers etc.
    Segments: Default is 36 - enter new value, must be 3 or more -
    more segments give smoother curves BUT more geometry !
    The geometry is in a Component named 'CymaCurve#1' or "CymaCurve#2"
    etc for multiple versions...
    Its description reflects its settings...
    It is attached to your cursor by its bottom left corner
    springing-point and it snaps to faces.
    You can mirror it by using Scale -1 or Move/Copy it as desired,
    or Explode as required...

    Get latest version from the PluginStore http://sketchucation.com/pluginstore?pln=CymaCurve

    TIG

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    • J Offline
      jason_maranto
      last edited by 7 Mar 2010, 21:59

      Wow TIG, I feel dumb just reading the descriptions of your plugins -- I know it muct be usefull, probably very usefull but I for the life of me could not figure it out.

      Guess I'll just have to download it and play ๐Ÿ˜‰

      Best,
      Jason.

      I create video tutorial series about several 2D & 3D graphics programs.

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      • P Offline
        pilou
        last edited by 7 Mar 2010, 22:08

        For stones carvers โ˜€

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

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        • J Offline
          JClements
          last edited by 7 Mar 2010, 22:21

          From wikipedia:
          "...The ogee curve is an analogue of a "cyma curve", the difference being that a cyma has horizontal rather than vertical ends..."

          Not sure what is meant by horizontal v.s. vertical ends.

          John | Illustrator | Beaverton, Oregon

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          • D Offline
            d12dozr
            last edited by 7 Mar 2010, 22:32

            This is an ogee(the leftmost part of the image):

            http://upload.wikimedia.org/wikipedia/en/9/9d/Molding-ogee.png

            So I imagine a cyma curve is rotated 90 degrees.

            Also useful for woodworkers...thanks TIG!

            @JClements: I was going to post that exactsame sentence from Wikipedia ๐Ÿ˜ฎ

            3D Printing with SketchUp Book
            http://goo.gl/f7ooYh

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            • J Offline
              JClements
              last edited by 7 Mar 2010, 22:51

              If you use the option to produce faces, the face extrudes with one "seam" along the cyma surface where the two arcs touch one another (can there be an option to "auto-weld" the two arcs?).

              ============================================
              Peculiar arcs are drawn.

              ?? BUG: If you click on the "lower" arc, it is a polyline. However, if you click on any portion of the "upper" arc, only a segment is selected (of a the 36 defining the arc), yet it can extrude a smoothed surface. How can this be?

              John | Illustrator | Beaverton, Oregon

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              • D Offline
                d12dozr
                last edited by 7 Mar 2010, 23:10

                @jclements said:

                ?? BUG:... However, if you click on any portion of the "upper" arc, only a segment is selected (of a the 36 defining the arc), yet it can extrude a smoothed surface. How can this be?

                I see that too...if you select one of the segments, actually 2 segments are selected - the one you chose as well as the segment at the end of the arc.

                3D Printing with SketchUp Book
                http://goo.gl/f7ooYh

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                • T Offline
                  TIG Moderator
                  last edited by 8 Mar 2010, 09:28

                  Here's v1.1 http://forums.sketchucation.com/viewtopic.php?p=230584#p230584

                  • FR lingvo by Pilou added.
                  • Faced option curves now welded as one so smooth extrusion without a mid-point join.

                  TIG

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                  • T Offline
                    TIG Moderator
                    last edited by 8 Mar 2010, 09:31

                    I'm looking at this 'BUG' where one of the arcs is in bits but still an arc ???
                    Update soonest...

                    TIG

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                    • T Offline
                      TIG Moderator
                      last edited by 8 Mar 2010, 09:41

                      Here's v1.2 http://forums.sketchucation.com/viewtopic.php?p=230584#p230584
                      The buggy second arc formation has been fixed - I simply made it a different way that now works - I think the problem had something to do with the curves being drawn the opposite directions but whatever it was it's now sorted ? ๐Ÿ˜’

                      TIG

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                      • T Offline
                        TIG Moderator
                        last edited by 8 Mar 2010, 09:51

                        Here's an explanation of the the 2 types of Cyma Curve...cymas.png

                        TIG

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                        • T Offline
                          TIG Moderator
                          last edited by 8 Mar 2010, 15:40

                          Here's v1.3 http://forums.sketchucation.com/viewtopic.php?p=230584#p230584
                          Fixed a potential glitch from a missing 'require deB...' ๐Ÿ˜’

                          TIG

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                          • M Offline
                            MALAISE
                            last edited by 8 Mar 2010, 18:47

                            Thx TIG

                            You've done a pretty good Job. I'm sure you enjoy coding ๐Ÿ‘

                            MALAISE

                            La Connaissance n'a de valeur que partagรฉe

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                            • G Offline
                              Gaieus
                              last edited by 8 Mar 2010, 19:39

                              Thatnks TIG - again!

                              This will definitely be very handy for my ogee arches (which I would probably use more often than cymas)

                              Gai...

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                              • T Offline
                                TIG Moderator
                                last edited by 11 Mar 2010, 12:37

                                Here's an update http://forums.sketchucation.com/viewtopic.php?p=230584#p230584

                                v1.4 20100311
                                Non-square forms now possible and sizes entered, X & Y.
                                VCB prompt now shows the chord-proportion value needed to get tangential ends - useful if it's a non-square form.
                                The arcs' segments can now be set.
                                'Gola' and 'Ogee' added to type descriptions.
                                Notes and lingvo files updated to match changes.
                                ๐Ÿค“

                                TIG

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                                • D Offline
                                  dedmin
                                  last edited by 11 Mar 2010, 12:52

                                  Clipboard-1.jpg

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                                  • T Offline
                                    TIG Moderator
                                    last edited by 11 Mar 2010, 13:06

                                    I assume you refer to the 'broken curve' ?
                                    It's down to how the arcs are drawn - I'll fix it ๐Ÿ˜’

                                    TIG

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                                    • T Offline
                                      TIG Moderator
                                      last edited by 11 Mar 2010, 13:38

                                      Here's an update http://forums.sketchucation.com/viewtopic.php?p=230584#p230584
                                      v1.5 The 'broken' curve/arc glitch is fixed and the form is now a welded curve made from the two arcs...

                                      TIG

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                                      • D Offline
                                        dedmin
                                        last edited by 11 Mar 2010, 14:10

                                        ๐Ÿ‘ ๐Ÿ‘

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                                        • L Offline
                                          lapx
                                          last edited by 11 Mar 2010, 15:45

                                          Thanks TIG!

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