Class AffineTransform

Object
   |
   +--AffineTransform

class AffineTransform

This is a class that specifies special matrices that are affine transformations of homogeneous coordinates and allows them to be applied to point2D and point3D objectss. This class is primarily used internally by the point2D and point3D classes, but can also be called as such, for example:
var T = new AffineTransform(3).rotationX(Math.PI);
var p3D = T.applyTo(new point3D(1,1,1));
The transformation methods return the current AffineTransform object, allowing compound transformation. Compound transformations are handled in reverse order. For example:
var T = new AffineTransform(3).rotationX(Math.PI).translate3D(1,1,1);
var p3D = T.applyTo(new point3D(1,1,1));
represents the following operation:
p3D = (translate3D(1,1,1) x rotationX(Math.PI)) x (1,1,1,1);
p3D =
([1 0 0 1] [1 0 0 0] ) [1]
([0 1 0 1] [0 -1 0 0]) [1]
([0 0 1 1] [0 0 -1 0]) [1]
([0 0 0 1] [0 0 0 1] ) [1]
(NOTE: [1 1 1 1] is the column matrix representation of the new point3D(1,1,1) object)
Note that the transformation methods update the current AffineTransform object (allowing compound transformations) while the invert() method creates a new AffineTransform object with the opposite transformation as its matrix.
Defined in AffineTransform.js

Requires:

- Matrix

Field Detail

dim

Integer dim

The dimension of the transformation (1 less than dimension of matrix).

matrix

Matrix matrix

The transformation matrix that will be created when specific methods are called.

AffineTransform

AffineTransform(<Integer> dim)

Construct a new AffineTransform object, which contains a dimension, a transformation matrix (set by instance methods), and the applyTo method.

Parameters:
dim - the dimension (2 or 3) of the Affine Transformation.

Requires:
- Matrix

applyTo

Object applyTo(point)

Applies the transformation to a point2D or point3D object.

Returns:
a point2D or point3D object, depending on the dimension called

invert

AffineTransform invert()

Inverts an Affine Transformation. This function IS different from inverting a Matrix. AffineTransform.prototype.See = http;://en.wikipedia.org/wiki/Affine_transformation#properties_of_affine_transformations

Returns:
a new AffineTransform object that does the inverse transformation of the original

invertible

Boolean invertible()

Tests to see if an Affine Transformation is invertible.

Returns:
true iff invertible, false otherwise

rotate2D

AffineTransform rotate2D(<Number> theta)

Rotates a point (x,y,1) about the angle theta in the xy-plane. Note that this is the same as Math.rotationZ in one less dimension.

Parameters:
theta - the degrees (in radians) to rotate the point by

Returns:
this AffineTransform object, with updated matrix

See:
- rotationZ()

rotation

AffineTransform rotation(<Number> theta, <Object> axis)

Creates a rotation matrix about an arbitrary axis.

Parameters:
theta - the number of degrees (in radians) to rotate
axis - (Optional) the axis (3-D Vector, point3D or Array) about which to rotate; if not supplied, assume 2D rotation of theta in XY-plane

Returns:
this AffineTransform object

rotationX

AffineTransform rotationX(<Number> phi)

Rotates a point (x,y,z,1) through an angle phi about the x-axis.

Parameters:
phi - the degrees (in radians) to rotate the point by

Returns:
this AffineTransform object, with updated matrix

rotationY

AffineTransform rotationY(theta)

Rotates a point (x,y,z,1) through an angle theta about the y-axis.

Parameters:
phi - the degrees (in radians) to rotate the point by

Returns:
this AffineTransform object, with updated matrix

rotationZ

AffineTransform rotationZ(psi)

Rotates a point (x,y,z,1) through an angle psi about the z-axis.

Parameters:
phi - the degrees (in radians) to rotate the point by

Returns:
this AffineTransform object, with updated matrix

toString

String toString()

Returns a string representation of the Affine Transformation matrix.

Returns:
the string representation of this transformation's matrix

translate2D

AffineTransform translate2D(<Number> tx, <Number> ty)

Creates a 2D translation matrix (3x3). To be applied to a 2D point (x,y,1) as such: (x',y',z',1) = translate3D*(x,y,z,1)

Parameters:
tx - the x-coordinate translation
ty - the y-coordinate translation
tz - the z-coordinate translation

Returns:
this AffineTransform object, with updated matrix

translate3D

AffineTransform translate3D(<Number> tx, <Number> ty, <Number> tz)

Creates a 3D translation matrix (4x4). To be applied to a 3D point (x,y,z,1) as such: (x',y',z',1) = translate3D*(x,y,z,1)

Parameters:
tx - the x-coordinate translation
ty - the y-coordinate translation
tz - the z-coordinate translation

Returns:
this AffineTransform object, with the matrix updated to the translate3D matrix