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Drumknott

Half Circle rotation animation

Warning: Please note

This thread was started before GSAP 3 was released. Some information, especially the syntax, may be out of date for GSAP 3. Please see the GSAP 3 migration guide and release notes for more information about how to update the code to GSAP 3's syntax. 

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Hi. This is my firs post.

 

I'm trying to learn animation in html5 and javascript.
So far, I worked a little bit with Flash.
But I do not understand a few things, I would ask for example, based on

 

See the Pen Guwtq by anon (@anon) on CodePen



I want to animate "item2".
So animation rotation, the path (inside) "elementu1".

I hope I wrote it correctly.

Thanks.

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You could try something like this:

http://codepen.io/GreenSock/pen/ijKvA

 

Note the

 

  //NEXT LINE VERY IMPORTANT
  context.clearRect(0, 0, canvas.width, canvas.height/2);

 

If you remove it, the anti-aliasing is really jagged as multiple strokes are getting piled on top of each other. 

 

The bad news is clearing the context gets rid of the light grey top semi-circle.

 

---

 

We can't tween arcs directly, but we can tween any numeric property of any javascript object and then apply those values however we want.

 

var props = {endAngle:1};


var tween = TweenLite.to(props, 3, {endAngle:2, onUpdate:updateAngle});

The onUpdate callback is pretty much your original arc-drawing function

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Thank you for your response.

I wanted to make an animation for a preloader images.
I'm not sure whether this method is good.

Here is an example in Flash.

I want to achieve this effect (attached File)

 

 

preloader2.zip

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oh, it appears you just want to rotate the circles, or more specifically the strokes.

 

Unfortunately, rotating individual canvas elements is non-trivial:

http://creativejs.com/2012/01/day-10-drawing-rotated-images-into-canvas/

 

I'd recommend looking into a canvas library like KineticJS or EaselJS and experiment a bit with using those libraries to create the artwork you want to rotate. Once you've created Kinetic or Easel objects its quite easy to animate their rotation with TweenLite.

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