Layer Space Transforms methods (expression reference)
图层空间变换方法
Use layer space transform methods to transform values from one space to another, such as from layer space to world space.
使用图层空间变换方法来变换一个空间值为另一个空间值，如同变换图层空间到世界空间
The “from” methods transform values from layer space to the named space (composition or world).
“from”方法变换图层空间到所命名的空间（合成空间或世界空间）
The “to” methods transform values from the named space (composition or world) to layer space.
“to”方法变换所命名的空间（合成空间或世界空间）到图层空间
Each transform method takes an optional argument to determine the time at which the transform is computed; however, you can almost always use the current (default) time.
每一个变换方法使用一个可选参数来决定哪个时间点的值用来转换计算，尽管如此，你也可以总使用当前时间（默认设置）。
Use “Vec” transform methods when transforming a direction vector, such as the difference between two position values.
当变换一个具方向的向量时，使用“Vec”变化方法，如两个“position”之间的差值
Use the plain (non-”Vec”) transform methods when transforming a point, such as position.
当需变换一个点时使用简易变换方法（不用“Vec”），如“position”
Composition (comp) and world space are the same for 2D layers.
合成空间和世界空间在2D图层里是一致的
For 3D layers, however, composition space is relative to the active camera, and world space is independent of the camera.
而在3D图层中，合成空间与活动摄像机有关，世界空间是独立于摄像机存在的
toComp(point, t=time)
返回类型: Array [2 or 3].
参数类型: point is an Array [2 or 3], and t is a Number.
Transforms a point from layer space to composition space.
fromComp(point, t=time)
Return type: Array [2 or 3].
Argument type: point is an Array [2 or 3], and t is a Number.
Transforms a point from composition space to layer space.
The resulting point in a 3D layer may have a nonzero value even though it is in layer space.
Example: fromComp(thisComp.layer(2).position)
toWorld(point, t=time)
Return type: Array [2 or 3].
Argument type: point is an Array [2 or 3], and t is a Number.
Transforms a point from layer space to view-independent world space. Example: toWorld.effect("Bulge")("Bulge Center")
Dan Ebberts provides an expression on his MotionScript website that uses the toWorld method to auto-orient a layer along only one axis. This is useful, for example, for having characters turn from side to side to follow the camera while remaining upright.Carl Larsen provides a pair of video tutorials on the Creative COW website in which he explains the basics of parenting and then uses an expression involving the toWorld method to trace the path of an animated child layer:
part 1
part 2
Rich Young provides a set of expressions on his AE Portal website that use the toWorld method link a camera and light to a layer with the CC Sphere effect.fromWorld(point, t=time)
Return type: Array [2 or 3].
Argument type: point is an Array [2 or 3], and t is a Number.
Transforms a point from world space to layer space. Example:fromWorld(thisComp.layer(2).position)
See Expression example: Create a bulge between two layers for an example of how this method can be used.toCompVec(vec, t=time)
Return type: Array [2 or 3].
Argument type: vec is an Array [2 or 3], and t is a Number.
Transforms a vector from layer space to composition space. Example: toCompVec([1,0])fromCompVec(vec, t=time)
Return type: Array [2 or 3].
Argument type: vec is an Array [2 or 3], and t is a Number.
Transforms a vector from composition space to layer space. Example (2D layer): dir=sub(position, thisComp.layer(2).position);
fromCompVec(dir)toWorldVec(vec, t=time)
Return type: Array [2 or 3].
Argument type: vec is an Array [2 or 3], and t is a Number.Transforms a vector from layer space to world space. Example: p1 = effect("Eye Bulge 1")("Bulge Center");
p2 = effect("Eye Bulge 2")("Bulge Center");
toWorld(sub(p1, p2))fromWorldVec(vec, t=time)
Return type: Array [2 or 3].
Argument type: vec is an Array [2 or 3], and t is a Number.
Transforms a vector from world space to layer space. Example:fromWorld(thisComp.layer(2).position)fromCompToSurface(point, t=time)
Return type: Array [2].
Argument type: point is an Array [2 or 3], and t is a Number.
Projects a point located in composition space to a point on the surface of the layer (zero z-value) at the location where it appears when viewed from the active camera. This method is useful for setting effect control points. Use with 3D layers only.
