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I'm trying to create a flat plane icon of a clock that can start full and over the course of time have it's outer edge swing 360 degrees around it's center point and then terminate when it's gotten back to it's starting point. An example would be this image of a clock but with just the green portion visible: http://cdn.vectorstock.com/i/composite/93,19/time-steps-icon-vector-749319.jpg

I really just started using Blender last week so I feel like I'm pretty in over my head. What I've seen so far suggest that Shape Keys could be a solution, but I'm not sure how to get a flat shape to link to a circle. An array modifier could also be a solution, but I'm not sure it'll work on a solid object.

Does anyone have a solution to this?

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An array modifier would work, but it would appear/disappear in steps. Would that be acceptable? –  gandalf3 Feb 24 '14 at 3:04
I would eventually like to have a nice, smoothly animating clock, but I might be able to make that happen if I set the number of objects on the array high enough right? Still it would be nice to know if what I'm asking for is impossible or not –  Stinkhorse Feb 24 '14 at 3:21
It would require an awful lot of segments.. There must be a better way.. –  gandalf3 Feb 24 '14 at 3:22
Even using Shape Keys requires a lot of segments to get a nice smooth look, but even then I'm still stuck at the point where I somehow link the shape keyed points to a curve. –  Stinkhorse Feb 24 '14 at 3:28

1 Answer 1

up vote 4 down vote accepted


The original method did not work due to a limitation of blender's interaction with the Carve library (used for boolean operations). Here is an updated technique.

Example file

You can do this using Boolean modifiers:

  1. Add a cylinder and a cube, then move the cube 1 BU on the X and -1 on the Y. With the cube selected, enter edit node and delete one edge:

    enter image description here

  2. Then select one of the remaining two face and press P> Selection:

    enter image description here

  3. With the 3D cursor in the middle, select each cubeface/plane object and press CtrlShiftAltC to snap the object origin to the 3D cursor:

    enter image description here

  4. Add a Union boolean modifier to plane 1 (it doesn't matter which plane is plane 1 and which is plane 2, but once you decide you shouldn't switch) and select plane 2 as the target object:

    enter image description here

  5. Add a Difference boolean modifier to the cylinder and select plane 1 as the target object:

    enter image description here

    Optionally add an Edge Split modifier to get rid of the dark shadows (only visible when the mesh is smooth shaded) caused by the poor topology produced by the boolean operation.

  6. Insert Rotation keyframes (I> Rotation) to animate the rotation of either plane:

    For example:

    1. On frame 1 with one plane selected insert a rotation keyframe (I> Rotation)
    2. Go to a later frame and rotate 360° on the Z (RZ360)
    3. Insert another rotation keyframe (I> Rotation)

    enter image description here

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Oh my god that is a thing of wonder! Thanks so much Gandalf! –  Stinkhorse Feb 24 '14 at 3:54
Ok I got everything set up as you described, but when I applied the difference modifier and targeted the first plane the entire cylinder vanished. So questions: Are the two planes a single object? I'm assuming no at this point because then how would you target the various parts of it? My other question was in regards to the animation but I suppose that can wait until I've solved this issue... –  Stinkhorse Feb 24 '14 at 5:58
The cylinder is definitely bisecting plane1, you can clearly see the alteration in that plane's geometry. –  Stinkhorse Feb 24 '14 at 6:06
@Stinkhorse what do you mean? –  gandalf3 Feb 24 '14 at 6:59
@Stinkhorse For some reason it only works when I start with a cube, delete one edge, and separate the remaining two faces into separate objects. Will report as a bug, that shouldn't happen.. –  gandalf3 Feb 24 '14 at 7:58

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