Ability to change radius from a extruded NURBS circle along a curve

# 1 08-07-2012 , 04:23 AM

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Join Date: Jul 2012

Posts: 2

Ability to change radius from a extruded NURBS circle along a curve

Hello!

I've been tapping my head to this issue for a little while now, and I would like to reach out for some help.
I am trying to create an animated line that flies around and moves around objects on the screen. While the line slithers around, it will change in "thickness." I've attempted to tackle this in a few ways but ran into problems with each of them:

1) I've tried creating a CV curve as a path for a line (or tube, since it can change thickness?) to move in, and created a cylinder to "attach to motion path." Then, I created a "Flow Path Object" on the cylinder for it to move more smoothly. The issue I've encountered though was that I couldn't change the length of the cylinder without it distorting or going off pivot.

2) I kept the same CV curve, but instead of creating a cylinder I created a NURBS circle and extruded it along the curve to create a tube. I could key the subCurb values to "animate" the movement of the tube, but I am left without the ability to manipulate the "radius" of the tube without it distorting/moving away from the pivot.

3) Same as #2 but instead of extruding with a NURBS circle, I extruded using the polygon faces of a cylinder. I lose the ability to key subCurb, and from there on I was unable to figure out a way to continue with this method.

I feel more inclined to continue with the second method because it was much simpler to just manipulate the subCurb value. However, adjusting the scale attributes of the extruded mesh did not simply increase its diameter, but expanded the entire mesh (not sure if I was able to word that correctly without confusion). I wonder if there are any solutions to this issue. I feel that I am missing something trivial that would solve this immediately. I appreciate any input.

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# 2 08-07-2012 , 10:14 AM

The thin red line
Join Date: Aug 2009

Location: England

Posts: 4,472

You could try making some joints them attach to motion path and flow path then skin a tube to the joins that might work, I think the problem you are having is the flow path lattic as soon as you expand out side of the lattic the mesh will be out side of it..........dave

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# 3 08-07-2012 , 06:14 PM

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Join Date: Jul 2012

Posts: 2

Hello Dave!

Thank you very much for your help! I've constructed a set of four joints and attaching them to the motion path. However, it seems that I am unable to create a flow path with the first joint and the CV curve; I get the error: "None of the selected objects are animated by a motion path with the Follow option." This is unusual since the Follow option is checked when I attached the joints to the motion path. (I've also looked around and found one advice to create joints and bind it to the cylinder and create a spline IK to attach to the curve, but that gave me a lot of other problems).

Ideally, the effect I wanted to achieve is similar to a snake moving around the screen that can increase or decrease in width (have the snake grow fatter or skinnier while it moves). So far I've been able to have it move around on a path, but I can't seem to find the ability to make it fatter/skinnier while moving on the path without it being displaced from the motion path itself. Perhaps this clears up any confusion? Thanks Dave!

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Ability to change radius from a extruded NURBS circle along a curve

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