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Turning Pages with Different sides in AE
I have a comp with a camera and 3D layers simulating pages in a book. Since the page has two sides, I’m using two layers for each page. When I put both layers really close to each other, AE gives me a bunch of glitches (especially with a moving camera and motion blur). So that doesn’t work.
I’m trying to write an expression that controls the opacity of a layer depending on whether it’s facing the camera. I’d like it to do this calculation no matter where I move or rotate the camera and/or the layer.
I tried an expression that calculates the angle between where the layer is facing and where the camera is facing to give me a value that I could use to manipulate opacity but there are situations where this doesn’t work like when the layer is rotated and moved to one side.
I’m thinking I need to calculate the worldspace angle of a vector from the coordinates of the camera to the anchor point of the layer and then use the vector I originally created from the layer to come up with the angle of view that will determine my opacity.
So I guess my question are:
1. Is there an easier way to do this?
2. If not, what expression would calculate the worldspace angle off the z axis of the vector from the position of the camera to the anchor point of a layer?Here’s my original code gave me an angle value that didn’t quite work.:
L=thisLayer;
cam=thisComp.layer(“Camera 1”);
u=L.toWorldVec([0,0,1]);
c=cam.toWorldVec([0,0,1]);
A=radiansToDegrees(Math.atan2(u[0],u[2]));
B=radiansToDegrees(Math.atan2(c[0],c[2]));
A-BI hope this isn’t too confusing. Thanks for all your help in advance.
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2 Replies
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Hi Josh,
I think this might be what your looking for.
if (toCompVec([0, 0, 1])[2] > 0 ) value else 0
There is a breakdown of the expression on Dan’s site
https://www.motionscript.com/design-guide/invisible-facing-away.html
-Andy
-Andy
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Jesus.
Thanks….
That works brilliantly.
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