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Extrude Along Path - Scale + Factor: Locked?

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I'm retaking Intermediate Concepts right now and I'm finding that the Scale option is un-editable in the OIP for an Extrude Along Path object:



Here's the path and object:



This is also true when I create a new Extrude Along Path object. The dialog doesn't allow you to change the Scale (type) or the Factor:


How do I fix this? 


After a little debug, if my path is a straight line, it works as expected:



As soon as I add in breaks in that path it doesn't work:



Seems like new behavior in VWX 2021


Edited by trashcan
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I'm seeing a slightly different scenario, but still a bit of a mystery.


Straight and (most) continuously curved paths offer the scale options.


But, if  path is several straight segments, eg polyline with intermediate corner vertices, the scale options are gray.  If same path is filleted, the scale options are available. Although if the fillets are too small, the EAP may fail, or have funky surfaces.


So, a theory:

In math, a continuous curve has only a single definition for each point (Search Continuous Curve this for more math info). A single function/formula defines every point along the entire path.  A poly with corner points is discontinuous in that each corner point is defined by two formulae - the same location (xyz) has two formulae associated (defining) it - it's the end/start point of two different forumlae .  vwx EAP cannot resolve more than one definition for each location in space. except . . .


vwx resolves the unscaled corner points via a mitering interpretation.  But attempting to scale the miter from two directions produces conflicts.


Filleting the corner points often allows the scaled EAP options, but the results can contain overlapping, self intersecting surfaces and volumes. Looks kinda weird, or fails.


Just blathering some generalized thoughts.  Others may have a better handle on this.



Edited by Benson Shaw
proving that I'm edumuhkated
  • Like 1
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I think you're right, @Benson Shaw I went back and through the tutorial on VWX university and it looks like I may have had an extra click when I created the polyline and my guess is it created additional vertices that makes the EAP fail. Since the new object turns the polyline into a nurbs curve, I don't think I can investigate the original path that failed the scaleability of the EAP. Can I?




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  • 1 month later...

Same problem. I drew two 3D polygons for the inner and outer hand rails of a stairway. The first one worked first time as the path for my profile object. The second not. Even after I reversed the direction of the path object in the OIP. But when I re-drew the 3D polygon in the direction away from the profile object the tool operated perfectly. So the only thing I can think of is that I had drawn the 3DPoly towards the profile object which may have prevented the tool working. And reversing in OIP wasn't effective. So  you have to draw the path in the right direction, away from the profile object, first time?


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Having multiple problems with Extrude along Path.  I am trying to draw a moulding profile to go around a rectangular porch post. The post corners are rounded.  It only needs to go around three sides - the back is open.  I drew a rectangle with rounded corners.  Then I drew the moulding profile.  I extruded the profile around the rectangle OK. 


Then I tried to subtract out the fourth side, but VW would not allow it.  Nothing I tried would work - “edit the profile” didn’t work….


So, I decided to create the rounded rectangle as a series of independent lines and arcs, with the back side open.  When I extruded the profile on a rounded section, it was inverted.  The moulding shape was toward the inside of the circle.  I tired every orientation of the profile and got exactly the same result each time - inward facing profile.  On a straight line, it works as expected.


Any ideas?  VW2020


Inverted Profile.png

Edited by BenG
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