Adobe 12040118 - After Effects Standard Tutorial page 563

Chris and Trish Meyer provide additional information about vector math methods and arrays in an article on the
add(vec1, vec2) Return type: Array.
Argument type: vec1 and vec2 are Arrays.
Adds two vectors.
sub(vec1, vec2) Return type: Array.
Argument type: vec1 and vec2 are Arrays.
Subtracts two vectors.
mul(vec, amount) Return type: Array.
Argument type: vec is an Array, amount is a Number.
Multiplies every element of the vector by the amount.
div(vec, amount) Return type: Array.
Argument type: vec is an Array, amount is a Number.
Divides every element of the vector by the amount.
clamp(value, limit1, limit2) Return type: Number or Array.
Argument type: value, limit1, and limit2 are Numbers or Arrays.
The value of each component of value is constrained to fall between the values of the corresponding values of limit1 and limit2.
Chris and Trish Meyer provide additional information about the clamp method in an article on the
dot(vec1, vec2) Return type: Number.
Argument type: vec1 and vec2 are Arrays.
Returns the dot (inner) product of the vector arguments.
cross(vec1, vec2) Return type: Array [2 or 3].
Argument type: vec1 and vec2 are Arrays [2 or 3].
Returns the vector cross product of vec1 and vec2. Refer to a math reference or JavaScript guide for more information.
normalize(vec) Return type: Array.
Argument type: vec is an Array.
Normalizes the vector so that its length is 1.0. Using the normalize method is a short way of performing the operation div(vec, length(vec)).
length(vec) Return type: Number.
Argument type: vec is an Array.
Returns the length of vector vec.
length(point1, point2) Return type: Number.
Argument type: point1 and point2 are Arrays.
Returns the distance between two points. The point2 argument is optional. For example, length(point1, point2) is the same as length(sub(point1,
point2)).
For example, add this expression to the Focus Distance property of a camera to lock the focal plane to the camera's point of interest so that the
point of interest is in focus:
length(position, pointOfInterest)
lookAt(fromPoint, atPoint) Return type: Array [3].
Argument type: fromPoint and atPoint are Arrays [3].
The argument fromPoint is the location in world space of the layer you want to orient. The argument atPoint is the point in world space you want to
point the layer at. The return value can be used as an expression for the Orientation property, making the z axis of the layer point at atPoint. This
method is especially useful for cameras and lights. If you use this expression on a camera, turn off auto-orientation. For example, this expression
on the Orientation property of a spot light makes the light point at the anchor point of layer number 1 in the same composition: lookAt(position,
thisComp.layer(1).position)
Random Numbers methods (expression reference)
Note: The wiggle method—which is used to randomly vary a property value—is in the Property attributes and methods category. (See Property
attributes and methods (expression reference).)
seedRandom(offset, timeless=false) Return type: none.
Argument type: offset is a Number, timeless is a Boolean.
The random and gaussRandom methods use a seed value that controls the sequence of numbers. By default, the seed is computed as a function
of a unique layer identifier, the property within the layer, the current time, and an offset value of 0. Call seedRandom to set the offset to something
ProVideo Coalition
ProVideo Coalition website.
website.
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