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Align arrowhead to a sweep

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I'm new to the forum, so first a big hello to all. I'm using c4d R19 student edition for this question....

What I'm doing: I'm animating points on a cylindrical sweep, this was done by using a joint tool on a spline and creating handles (nulls) for each joint/point (method is here ). This way I can animate the nulls and the sweep stays live (not editable). It all works well. I've put a cap (arrowhead) in the null at the end of the spline/sweep, which looks great when vertical (top left image) but when the null (spline handle) is moved (straight across with no rotation) the joint/angle of sweep rotates and the arrowhead stays vertical (top right image).


The bottom images shows what I'm trying to do, but have faked in photoshop. Does anyone know of a way to align the arrowhead with points, polys or edges so that the arrowhead will stay in line (perpendicular) to the cylinder? For animation purposes the sweep has to stay a sweep (can't make it an editable object).


Maybe I'm doing this all wrong and should be using another method entirely? 


Any help would be greatly appreciated. Thanks in advance!


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Hi and :welcome: to the Cafe


Would be easier if you posted a scene file, however you can always use spline tangent data for orientation. Check this example :)




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Here's a method using Align to Spline.  With such sharp turns, you're bound to get some ugly popping when the arrowhead passes them.  I set up an example which sort of helps with this problem using a Delay Effector in Blend mode to smooth out the rotation.

tangent- with Align to Spline.c4d

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Thank you both for responding to my question, much appreciated. I'm going to takeHrvoje up on his suggestion and post a file that shows what I'm trying to do.


To clarify better, the spline I'm animating isn't growing, its just moving around (wiggling) on a plane (2 dimensions). The spline points are the nulls, and moving them (hopefully in a random motion setup) will animate the spline. It's also set up this way because I want the polys to be a fixed number as I'm going to assign a different material to different poly groups and don't want the number of polys to grow/change. All of this will be subd'd and corners will be smoothed.


The problem is that the top two points (nulls) determine the trajectory of the sweep, and this is what I want the cone (arrowhead) to dynamically follow, or stay aligned to. I'm wondering if I can set up 'dummy' geometry  on the surface of the sweep, link the cone to the sweep surface, or make a guide line between the points that the cone can align to (or be perpendicular to). Other ideas?


If there are any ideas how to do this please let me know, I'm stumped. Thanks!


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This should work (see attached).  I'm a little concerned about your idea of dropping it into an SDS and hoping it looks good.  My results were not great:



I suggest adding some intermediate points in your spline, then using a mask (gradient with Step interpolation) to select your 3 different areas for different materials:

Arrow v2.c4d

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Thanks so much natevplas, this is exactly what I'm trying to do! I didn't know it was as easy as aligning to spline, I guess I was making it harder than it needed to be. I really appreciate the extra suggestions for making it look smoother, thanksyou!!!  And thank you all for your input!!!

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