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Kent1Cooper
en respuesta a: Karol-Or


@Karol-Or wrote:

I never understood the Extrusion Direction, how is it created?


It's a unit vector representing the direction that the Z axis "aims" in World Coordinates for an object.  If you Extrude something with a positive extrusion distance, it's the direction that extrusion extends from the object; or, if you give something Thickness, it's the direction the thickness extends.  If you're drawing in the WCS, everything's extrusion direction when drawn is 0,0,1 [or, as expressed in entity data lists, (210 0.0 0.0 1.0) -- it's also the VLA "Normal" Property].  It will be different if something is drawn in a UCS whose XY plane is not parallel to the WCS XY plane, or if something has been Rotated 3D-wise from its original drawn position.

 

Some things [e.g. 3DPolylines] "have" one, from when they were drawn, that's kind of meaningless from the point of view of setting a UCS, since a 3DPolyline does not define one and can't be given Thickness [although you can Extrude one -- you get Surfaces rather than a 3D Solid].  Some things [e.g. non-planar Splines] don't have one at all.  Lines are peculiar because they can have delta-Z difference without  their extrusion direction being perpendicular to a plane they lie in, the way it must be for many object types [Circles, Arcs, 2D Polylines, Text].

Kent Cooper, AIA