Sketch Anchor to Origin

MTAK
MTAK
in 3D Modeling

Hello. Bricscad newbie question, but how can I "anchor" my parametric sketch to origo? Zero point wont have anything to snap on and coincident constraint always need some point to snap. Fix command also not fixing the line on origo.

Comments

  • Virgil
    Virgil

    Hello.

    The origin point can't be used as a reference.
    This behavior reflects the one in Autocad.

    Something that might be worth investigating is to use some additional geometry and fix it to the origin.

    For example, you could draw two lines, each having a point in the origin.
    One line could be horizontal, and one, vertical, tho create a coordinate system.
    Each line could be constrained accordingly, horizontal or vertical.

    Then, using a fix constraint, a line could be constrained to have a fixed point, specifically the one in the origin.
    The other line could be constrained similarly. Or, a coincident constraint could be used.

    Finaly, the two lines could be placed on a separate layer.
    This would allow to hide them in the main drawing.

  • MTAK
    MTAK
    edited October 28

    Really, no any solid command for this? How can I fix the additional geometry to origin, if the actual geometry cannot either to be fixed to origin?

  • MTAK
    MTAK

    I tried to make additional geometry to origin(red) and freeze that layer so that it will not move. When I add coincident constraint, sketch(blue) wont move, part of the additional geometry moves…even that additional geometry layer is freezed over.

    image.png

  • Virgil
    Virgil

    Hello.

    Freezing a layer won't fix any entity in place.
    When freezing a layer, the entities on it are not regenerated when REGEN is run.
    This is useful for performance, but not directly related to constraining.

    One way of working could be to constrain 2 lines in the origin and use them constrain other entities.
    The layer with these 2 lines can be turned off, if those lines shouldn't be visible.

    See reference_system.dwg
    The lines can't be moved.
    However, they can be lengthened along the axis each is constrained to.
    This can be controlled by adding 2 dimensional constraints, if needed.

    To fix the endpoint of a line in the origin:

    • Draw the line with an edn point in the origin.
    • Use a Fix constraint and fix the endpoint from the origin.

    See constrain_to_origin.dwg

    reference_system.dwg
    constrain_to_origin.dwg

  • MTAK
    MTAK

    Hello. Works somehow now, needs more testing. Thank you for those examples. :)