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Revolve Primitive?

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2012-10-01
2013-04-22
  • Greetings,
         In a number of places here and in old BRL-CAD documentation, I have found references to a "revolve" primitive.  I think this object is a surface of revolution about an axis for a set of connected points or line segments.  However, if i go into MGED and try "in qq.s revolve", it says it doesn't know about revolve.  Does anyone have any info in this and, if it exists, a worked example I can try?  Thanks!

     
  • Sean Morrison
    Sean Morrison
    2012-10-01

    There indeed is a revolve (surface of revolution) primitive in BRL-CAD, but know that it's considered an experimental primitive.

    It sounds like you're using a really old version of BRL-CAD.  If I recall correctly, revolves were added in 7.12.6 so you certainly won't see it before that.  You couldn't apply a matrix edit to them until 7.18.4, so it won't be incredibly useful before that.  I don't know when the 'in' command support was added.  I'd suggest using the very latest if you need revolves regardless in case you run into an issue.

    There is low-level developer details on the primitive here: http://brlcad.org/wiki/Revolve_Primitive
    Otherwise, the 'in' command will interactively prompt for parameters and you can play around with settings once you have a sketch to revolve (see http://brlcad.org/wiki/Sketch).

    Cheers!
    Sean

     
  • Hello Sean,
        Thanks so much for the info.  I suspected this and had downloaded version 7.22.0.  I am seeing it in MGED 7.22 now, so it must have been pilot error before.  Thanks also for the references.  I will study them.

     
  • Sean Morrison
    Sean Morrison
    2012-10-04

    Glad to hear it.  If you have any questions, feel free to ask them here, on our users mailing list, or on our IRC channel.

    Cheers!
    Sean