Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 585

startFade = 500; // Start fade 500 pixels from camera.
endFade = 1500; // End fade 1500 pixels from camera.
try{ // Check whether there's a camera.
C = thisComp.activeCamera.toWorld([0,0,0]);
}catch(err){ // No camera, so assume 50mm.
w = thisComp.width * thisComp.pixelAspect;
z = (w/2)/Math.tan(degreesToRadians(19.799));
C = [0,0,-z];
}
P = toWorld(anchorPoint);
d = length(C,P);
linear(d,startFade,endFade,100,0)
The fade starts at a distance of 500 pixels from the camera and is complete at 1500 pixels from the camera. The
interpolation method is used to map distance values to opacity values.
linear
See also
"Add, edit, and remove expressions" on page 545
"Create a camera layer and change camera settings" on page 179
Example: Make a 3D layer invisible if facing away from camera
❖
Apply the following expression to a 3D layer's Opacity property:
if (toCompVec([0, 0, 1])[2] > 0 ) value else 0
See also
"Add, edit, and remove expressions" on page 545
"Create a camera layer and change camera settings" on page 179
Example: Flip layer horizontally if facing away from camera
❖
Apply the following expression to a 3D layer's Scale property:
if (toCompVec([0, 0, 1])[2] > 0 ) value else [-value[0], value[1], value[2]]
See also
"Add, edit, and remove expressions" on page 545
"Create a camera layer and change camera settings" on page 179
Example: Animate scale at each layer-time marker
❖
Apply the following expression to a Scale property to make a layer wobble at each marker:
AFTER EFFECTS CS3 579
User Guide