How can I animate a curve extending? I'd like the animation to look like a circle extruding along the path.

I've found lots of tutorials like this, using the taper/bevel objects in the curve settings, but I'm trying to do to it without the funky taper off the front of the extrusion.


1 Answer 1


You can do this by using a Bézier extrusion with animated start/end values, which was added in Blender 2.65. You'll need two curve objects: the path and the circle (if you don't have a circle curve, just add a CurveBezier Circle).

First, select the path, and set its Bezier Object (under the curve options tab) to the circle. This will take care of the extrusion portion. To avoid the "funky taper," just don't set the taper object.

Then, animate the End Bevel Factor value. To do this, go to frame 1, and set the End Bevel Factor value to 0. Hover over it and press I, or RMBInsert Keyframe to insert a keyframe. Then, go to the frame where you want the transition to end, set the factor to 1, and insert a keyframe again.

This image demonstrates the two key things to set:

Example image

NB Using the circle as a curve object allows you to have a more flexible swept object. If all you need really is a circle with no endcaps, just set the Bevel Depth to a higher value than zero and set the Fill to Full instead of Half.

  • 2
    $\begingroup$ Ahhh so simple. I've been trying unsuccessfully to understand the taper object... still don't get it at all, so thought I was missing something there. $\endgroup$
    – ajwood
    Commented Aug 8, 2013 at 23:07
  • $\begingroup$ The taper object adjusts the thickness along the length of the path. If you don't want this, don't use it. $\endgroup$
    – wchargin
    Commented Aug 8, 2013 at 23:08
  • $\begingroup$ If you want to animate the bevel of a closed path (cyclic), you won't be able to. You can, however, "break" a cyclic path and place a point exactly where the loop would "close", that way it'll look like it's a cyclic path but it won't be and you will be able to use the method mentioned above to animate it! :) $\endgroup$
    – prubini87
    Commented Sep 16, 2018 at 3:35

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