animated mask question

[Rhett Robinson]

Hi Judy,
Perhaps I’m misunderstanding the question, but that does seem rather simple… choose the layer with the mask in the timeline, hit “mm” to bring up the mask properties, then click the stopwatch next to the “mask shape” Move forward in time a while, then make a change to the mask (the quickest way to select the entire mask, and not a single point, that I’ve found is to click on the mask name.) If it’s not visible, make sure that the “toggle view masks” button is depressed at the lower left corner of the comp window.
Let me know if I’m not understanding the question, or if you have any others.
Rhett

[Judita]

well the thing is, I need to animate the rotation of the mask. I can use the free transform tool to rotate the mask, but how do I keyframe the rotation?

[Rhett Robinson]

Hi Judy,
By using the free transform tool, I believe that you are animating the rotation of the layer, and not just the mask. The points of the mask itself must be transformed, and not the layer, for the image to remain in the same rotation. If you just need the shape of the mask to rotate, you may need to put the mask on a black solid, and set the “track matte” of your photo to the black solid layer (you need to turn off the visibility of the black solid layer…), then you can animate the rotation of the black solid to achieve the effect.
Does that work for you? If that’s what you need, then you will not be animating the mask itself, but the black solid, so you would keyframe the rotation properties of the solid, and not the mask.

Maybe that is what you need, but let me know if that’s not it still!
Rhett

[Judita]

“By using the free transform tool, I believe that you are animating the rotation of the layer, and not just the mask. ”

Yep, you’ve got it – the mask itself is what I want to rotate.

The points of the mask itself must be transformed, and not the layer, for the image to remain in the same rotation. If you just need the shape of the mask to rotate, you may need to put the mask on a black solid, and set the “track matte” of your photo to the black solid layer (you need to turn off the visibility of the black solid layer…), then you can animate the rotation of the black solid to achieve the effect.

And that is indeed what I’ve done! Great minds think alike, eh?! ;-)I made a precomp with the fill, a black layer scaled much larger above it with the mask, and used an alpha inverted matte on the fill track matte. This way the corners of the black layer won’t appear when I rotate that precomp in my main comp.

Thanks for your help… It’s been a long week and I’m just tired of thinking.

TGIF!

[Mike Clasby]

For your future refence you can do what you want a little more straight-forwardly.

Set a Mask Shape keyframe like mentioned earlier, go down the timeline, double click a mask vertex (point, node, one of those little square dots on the mask) and you get a “free-transform” box around the mask(like in Photoshop). Rotate the “free-tranform box” and the Mask Shape will animate.

One Mask on one clip, the clip stays upright, the Mask rotates.

[Spritemaster]

I think the problem with this approach is that using this method doesn’t really cause the mask to rotate, since the mask points will interpolate between the two keyframes in *linear* paths. If you only have two mask shape keyframes, AE has no way of knowing you had “rotate” in mind, even though you used the rotation tool to create the second key frame. All it knows is – mask points were here, now mask points are there, let’s move them from here to there.

I believe the only workaround is the one suggested in this thread, to attach the mask to another layer and rotate the layer. Basically there’s no way to rotate a mask using shape animation, unless you keyframe it frame by frame which sort of defeats the purpose.

AA

[Mike Clasby]

Ah, yes, your are correct,upon closer perusal, I see a wow in the oval as it rotates. Ouch.

[Judita]

Would be a nice feature to have.

[Thehardmenpath]

There is, I am not used to it, but there is an option for that since version 6, I think, called “smart mask interpolation”.

But for what you want to do, just duplicate the layer and make a track matte. This is, make the “modes” visible in the timeline. Now delete the mask in the lower layer and, in the “modes” column, where there is a “none”, choose in “alpha matte (name of the upper layer)”. Now rotate the whole upper layer as much as you want.

[Rhett Robinson]

Wow – Thanks! This is the reason I hang out here! Even though I vaguely remember seeing something about that in the Meyer’s AE books, I’d completely forgotten about it. Although it isn’t necessarily applicable here, I spent an hour or so playing with the smart interpolate and came up with some interesting results – I’ll definitely add it to my arsenal!
Rhett