As i am new to blender i decided to learn by recreating some animations which have some interesting problems, and gain more knowledge about how tv intros are being done, collecting some parody intros to videos. I came across a simple yet troublesome effect , found no answer by googling or getting through tutorials and testing methods on this case led me to nowhere.


I attempted to recreate the animation above, especially the extending/appearing/drawn white strip with "randomly" placed gaps , strip which travels just above surface , casting shadow.

Tried dynamic paint,( with alpha channel) image sequence texture but although effect was very similar, whole invisible strip was casting shadow being Z transparent, in places where white color haven't reached yet.

I tried bezier curves as well(vector mode) but it appears that taper cant profile part in squary way, or maybe i am missing something here.

Shape keys seem to hard way to go , while keeping whole animation of stripe "unrolling" at constant speed.

I tried as well putting an array of planes on the path but it is completely not what i attempt to achieved.

I will edit post and add some pictures tomorrow.


There are a few methods that you could use to achieve this, some simpler, some more flexible. The one that follows can give you results similar to what's shown in the video.

First create a curve object that roughly follows your desired path, bevel its corners so you get less distortion on tight curves. In this example I use the great Curve Fillet Tool addon from the Blender CG Cookie Market (it's a paid extension, but worth the price IMHO), you can also use the Simple Curves Addon or just do it manually if you prefer.

Add curve

Now add a plane object, scale it lengthwise so it's narrowest side is placed along the curve length for better precision. Also scale the other direction to match the desired line thickness. Make sure you apply the scale before proceeding.

Add an Array modifier to you plane, and set it to Fit Curve and pick the previously created curve. Tick the Option Merge to join the arrayed planes.

Now add a Curve Modifier on top of it, set it to the same curve and it should distort it along the curve length. Make both the plane and the curve coincide at the same scene coordinate to avoid unwanted distortions.

Plane Array

Now the magic all comes from a Build Modifier, which will make the strip like effect progressively grow along the curve as desired. (Scrub the timeline to see the effect)

Build Modifier

If you want more control, optionally apply the Array and Curve Modifier Modifiers only (leaving the Build Modifier live) if you later wish to manually adjust the shape of the strip, like different materials along the path, varying width, colors or add gaps, otherwise leave all modifiers live for a more flexible non destructive workflow.

Final Strip

  • $\begingroup$ Thank you very much. I was closer than i thought but didn't consider applying modifier as a way to model and then put the gaps. Thank you very much again. I gave you an upvote but stackexchange won't let it effect because its my first steps. $\endgroup$ Sep 23 '16 at 3:29
  • $\begingroup$ Yes, it's a shame one has to apply the modifiers, I am a strong advocate of fully procedural non destructive workflows, but in this case I figured no other way around it. No problem don't worry about the vote; optionally you may also consider marking it as correct if it did solve you problem $\endgroup$ Sep 23 '16 at 4:52
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    $\begingroup$ And in terms of applying modifiers , i found the way to place gaps (evenly though, at regular inervals) by just applying more array modifiers on top of each other, one for grouping planes, another for grouping groups, and another to fill the curve with that pattern $\endgroup$ Sep 23 '16 at 17:19
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    $\begingroup$ Yeah, but then you get black mess with normals (i mean by that overlapping planes , not sure yet what normals exactly are for planes) in render . Hovewer i got the same on radii without using an addon, after applying modifiers i delete overlapping planes in corners and you can get it that way. $\endgroup$ Sep 23 '16 at 17:36
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    $\begingroup$ No, I don't think there is, as far as I know. Build Modifier is quite limited in that regard, you can only adjust the Start and Length parameter. For more advanced control you may use bezier curves with a Start and End bevel offset $\endgroup$ Sep 27 '20 at 17:25

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