spring rotation script for rod roll text animation

[Chris Wright]

sounds like a job for my handy dandy inertial bounce expression.

https://forums.creativecow.net/thread/227/14268

https://technicolorsoftware.hostzi.com/

[Brian Yarnell]

Those expressions rock! Does anyone have a helpful expression, or other quick way, to get the text to only be visible when it is facing a camera?
Thanks

[Chris Wright]

well a layer invisible when facing away from the camera could be a vector. just paste in opacity of text set as 3D.

if (toCompVec([0, 0, 1])[2] > 0 ) value else 0

or fade gradually -courtesy of Dan’s handiwork!

fadeAngle = 35;
v = toCompVec([0,0,1]);
d = length(toWorld(anchorPoint),thisComp.layer(“Camera 1”).toWorld([0,0,0]));
c = v[2]/d;
ease(c,Math.cos(degreesToRadians(fadeAngle)),1.0,0,100)

—
also I got this working which I find incredibly useful.

name your rectangle “End 2” and paste this in rotation of the arrow with an added slider

Now you can use a dummy system so that you can parent objects, and the code will always auto orient to the layer being called to.

follow2 = “End 2”
diff = sub(position,this_comp.layer(follow2).position);

(Math.atan2(diff[1],diff[0]) * 180/Math.PI) + 180+effect(“Slider Control”)(“Slider”)

https://technicolorsoftware.hostzi.com/

[Manojit Ghose]

hi chris!

you are dead right on what i wanted! thanks a ton. 🙂
one more question! in AE 3d space any object is seen on the both sides (like a 2 sided material in 3d apps) is there a way to make it visible only on one side (like a object is visible only the side it has normals facing in a 3d app.).

MG

[Chris Wright]

a simple test to lookAt the orientation data from the layer

an expression which orients a layer towards a camera can be used backwards to get data to create an if statement for opacity. Simply see what data it gives and put that in the if statement.

NOT tested…

orientation expression

L = thisComp.layer(“Camera 1”);
lookAt(fromWorld(L.toWorld(L.transform.anchorPoint)),transform.anchorPoint)

https://technicolorsoftware.hostzi.com/

[Chris Wright]

Apply this expression to the opacity, it’ll disappear whenever it’s flipped away from the camera

a = toWorldVec([0,0,1]);
b = thisComp.activeCamera.position – toWorld(anchorPoint);
c = dot(a,b)/length(b);
if (c > 0) 0 else value

—

Apply this expression to your ‘Scale’ attribute and it’ll automatically ‘flip’ the layer in 3d space when the camera goes behind it. This way, your text will never be seen from behind, for instance.

[(toCompVec([0, 0, 1])[2] > 0 ? 1 : -1) * scale[0], scale[1], scale[2]]

https://technicolorsoftware.hostzi.com/