How to create a curved arrow?

Support Modeling
1

In my “3D diagram”, I want to draw a flat arrow that shows how an object is being rotated. So imagine a flat arrow, then roll it around a cylinder to make it curved. When viewed in the plane, it will look like an elongated rectangle with a triangle glued to the short end. From the side, after curving, it will look like the letter C.

Now, this should be a simple task, right? But I cannot figure out how to do it.

  1. I tried subsurf, because that’s what I know best. However I’m having trouble with the arrowhead. To make the sides of the arrowhead pointy, I need to crease the edges. But this will also make a sharp corner where the arrow’s “shaft” meets the “point”, and that is not what I want. See the attached image, where I put the 3D cursor on the overly sharp edge.

  2. I also tried a Bezier curve, which works fine as long as I work in the plane, but when I want to curve it I need to switch on the 3D option in the Curve and Surface panel, and the curve is no longer filled.

  3. Finally I tried NURBS but I couldn’t figure out how to extrude the sides of the square NURBS plane to create the topology I wanted. In any case, from what I read on the web and in these forums, NURBS in Blender are not very usable at the moment.

Is there another approach that I’m overlooking? Is there a way to make any of these do what I want?

Thanks very much for your answers!

Attachments

arrowproblem.png659×845 22.9 KB

2

Have a look at the tutorial in my sig for simple polyflow to make the arrow work in subsurf.

This polyflow will work for the tip: (just one side of it not the solid of course and you could then extrude it.)

http://www.lightwiki.com/images/6/69/Tetra3.gif

This polyflow will work for where the tip attaches to the stem:

http://www.lightwiki.com/images/5/52/LetterA6.gif

Based on these concepts:

Cross hatch for the tip and stem square ends,

http://www.lightwiki.com/images/5/59/CrossHatch3D.gif

Tight edge loop for the head connection.

http://www.lightwiki.com/images/d/d0/EdgeLoop2.gif

Basically if you do this and then have enough segments you can then just bend it.

3

Wow, thanks very much for this detailed explanation! I’ll try this tomorrow!

4

No Prob.

Here’s something that will give you a better idea about where to put the polyflow I am talking about.

Attachments

Arrow.jpg888×615 97.3 KB

5

I would just convert a flat arrow to a mesh and add a curve modifier. Then you can tweak the bend by editing the curve.

Just drag the arrows in the BLEND file along the X-Axis.

Attachments

Arrows_2.blend (37.5 KB)

6

That is a cool technique. I love this aspect of Blender. The only problem of course is that unless you have a good number of segments you’ll see stepping on the curve of the arrow. The same technique could work on a subsurf mesh with smooth results so no reason not to use both.

7

That curve modifier solves it! I didn’t even know of its existence… Now I can just subsurf, and have the modifier deform after that. Even better, if I want to change the direction of the arrow I can just change the curve. Wonderful! Thanks a million!