I'm animating a mask using the screw modifier and Boolean. but as the mask starts to reveal the LED lights, because its a consecutive flow animation, it's revealing bit by bit the LEDs, rather than one full LED at a time. How can I make the LEDs animate one at a time as the goes around revealing the LEDs.


enter image description here

  • 1
    $\begingroup$ you could choose another method like an array around an offset and you just increase the count? $\endgroup$
    – moonboots
    Dec 5, 2020 at 13:24
  • $\begingroup$ That worked well, only one thing from making it what I'm after, I cant set the array to 0, Its always 1. So one LED is always visible: ibb.co/vQH1XjV $\endgroup$ Dec 5, 2020 at 13:34
  • $\begingroup$ Several answers here blender.stackexchange.com/questions/194078/… . Or using the array consider making it invisible when needed. $\endgroup$
    – lemon
    Dec 5, 2020 at 13:41
  • $\begingroup$ you can make the object invisible at the beginning (for example keyframe its visibility in the Outliner) $\endgroup$
    – moonboots
    Dec 5, 2020 at 13:59
  • $\begingroup$ I was this article on BSE, but I'm getting a message it cant be animated, is this what you are referring to? ibb.co/Gx6G366 $\endgroup$ Dec 5, 2020 at 14:25

1 Answer 1


At last, a use for the Build modifier?

Create a fan-filled circle-mask with the same number of segments as you have LEDs, rotate in Z to the desired start-point. Give it a Build modifier, set to the appropriate frame start/end, and 'Reverse'.

enter image description here

Segments are made visible one at a time.

@blender breath Thanks for the comment.. 'mask' is a bit vague - it could be so many things..

  • For a 3D mask, as you have done, assign a Solidify modifier to the circle, to get a cylinder disappearing in chunks, which can be used in a Boolean to cut away the LEDs
  • 2D, a perfectly black Diffuse BSDF mask in a black world,
  • Or, as here, 2D, a Holdout mask through to transparent film, composited against a coloured background -

or, I'm sure, many other possibilities, for use in compositing, or as a texture.

enter image description here

  • $\begingroup$ That worked well. For a minute I was confused when you mentioned "mask" I was selecting the circle triangle fan and then the LEDs and doing a Boolean (Ctrl + minus on the number pad) thinking that would be the masking method, but the result was awkward . Then occurred Ill try adding the solidify modifier to the Build modifier and got the same results as your animation. Is this the same way you did yours? streamable.com/falxid $\endgroup$ Dec 6, 2020 at 3:38
  • $\begingroup$ @blenderbreath Oops, that wasn't very clear, was it? Thanks. See Edit. $\endgroup$
    – Robin Betts
    Dec 6, 2020 at 9:38
  • $\begingroup$ Heaps better now, Cheers! $\endgroup$ Dec 6, 2020 at 23:15

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