How to get the global position of parented objects.

[Peter Stenhouse]

So “lookat” will point an object at another, but it won’t return values outside of -90 to 90 degrees. how do I get it to Look at with a range of 360 degrees?

small flowers crack concrete

[Dan Ebberts]

To get the world position of a parented layer, you need to use the layer’s anchor point, like this:

L = thisComp.layer(“Null 1”);
L.toWorld(L.anchorPoint)

Dan

[Dan Ebberts]

To get the world position of a parented layer, you need to use the layer’s anchorPoint, like this:

L = thisComp.layer(“Null 1”);
L.toWorld(L.anchorPoint)

Dan

(edit) – oops – duplicate post, sorry

[Andy Engelkemier]

How does this work with rotation?

I’ve got a glow on an object in 2D. Well, that doesn’t work if it rotates. So I would like to do the 3D rotation in a nested composition, and apply a glow to the result. This worked great for the position, but I nee to match the orientation. The layer I’m using for position is liked to another, so it appears to have no rotation.

I tried:
L = comp(“Ignite 4 animation”).layer(“u Outlines”);
L.toWorld(L.transform.orientation);

But at the start time, it should be orientation 0,0,0, but it’s actually 49.5, 347.5,0 so I’m a bit lost.

I did get it to do what I want, but not in the way I was hoping. I’m just linking the rotation to the Null I’m using to control rotation. And I’m hooking the position to a copy of the same layer that I’m simply turning off.

Is there an easier way to precomp a layer and have it’s attributes automatically assigned to the appropriate places via expressions? That would be killer. It’s pretty annoying to have to change everything to comp. I’m not sure if there is better way of doing this.

What I’m trying to learn here is if you can match the world orientation. It’s not seeming to work for me how I expected. Something is happening, it just doesn’t make sense to me yet.

[Dan Ebberts]

Generally, something like this works to get the world orientation of another 3D layer:


L = thisComp.layer("Source");
u = (L.toWorldVec([1,0,0]));
v = (L.toWorldVec([0,1,0]));
w = normalize(L.toWorldVec([0,0,1]));

sinb = clamp(w[0],-1,1);
b = Math.asin(sinb);
cosb = Math.cos(b);
if (Math.abs(cosb) > .0005){
c = -Math.atan2(v[0],u[0]);
a = -Math.atan2(w[1],w[2]);
}else{
a = (sinb < 0 ? -1 : 1)*Math.atan2(u[1],v[1]);
c = 0;
}
[radiansToDegrees(a),radiansToDegrees(b),radiansToDegrees(c)]


It gets more complicated though if you’re transforming coordinates between an object in a parent comp and another in a nested precomp.

Dan

[Steve Edwards]

I used Dan’s suggested

L = thisComp.layer(“Null 1”);
L.toWorld(L.anchorPoint)

with no joy. (Well, it shifted the camera way off axis and nowhere near the parented null) Then I found on another site that copying and pasting direct from a website can have peculiar results and it suggested I use something like TextEdit or SimpleText first.

Viola! Worked just as Dan said it would.

Now you know.