com.vividsolutions.jump.warp

Class AffineTransform

java.lang.Object

com.vividsolutions.jump.warp.CoordinateTransform

com.vividsolutions.jump.warp.AffineTransform

public class AffineTransform
extends CoordinateTransform

An AffineTransform implementation that is initialized by specifying three points and the three points they map to.

From http://graphics.lcs.mit.edu/classes/6.837/F01/Lecture07/lecture07.pdf:

      [ x1_ ] = [  x1 y1 1  0  0  0  ] [ a11 ]
      [ y1_ ] = [  0  0  0  x1 y1 1  ] [ a12 ]
      [ x2_ ] = [  x2 y2 1  0  0  0  ] [ a13 ]
      [ y2_ ] = [  0  0  0  x2 y2 1  ] [ a21 ]
      [ x3_ ] = [  x3 y3 1  0  0  0  ] [ a22 ]
      [ y3_ ] = [  0  0  0  x3 y3 1  ] [ a23 ]
 x_ = X a
 Solution: a = Xinv x_
 

Constructor Summary

Constructors

Constructor and Description
AffineTransform(com.vividsolutions.jts.geom.Coordinate p1, com.vividsolutions.jts.geom.Coordinate p1_) A transformation that maps p1 to p1_ via a translation (no rotation or shear).
AffineTransform(com.vividsolutions.jts.geom.Coordinate p1, com.vividsolutions.jts.geom.Coordinate p1_, com.vividsolutions.jts.geom.Coordinate p2, com.vividsolutions.jts.geom.Coordinate p2_) A transformation that maps p1 to p1_ and p2 to p2_ via a translation, rotation, and scaling (no "relative" shear).
AffineTransform(com.vividsolutions.jts.geom.Coordinate p1, com.vividsolutions.jts.geom.Coordinate p1_, com.vividsolutions.jts.geom.Coordinate p2, com.vividsolutions.jts.geom.Coordinate p2_, com.vividsolutions.jts.geom.Coordinate p3, com.vividsolutions.jts.geom.Coordinate p3_) A transformation that maps p1 to p1_, p2 to p2_ and p3 to p3_.

Method Summary

Methods

Modifier and Type	Method and Description
static com.vividsolutions.jts.geom.Coordinate	rotate90(com.vividsolutions.jts.geom.Coordinate a, com.vividsolutions.jts.geom.Coordinate b) Determines where a point would end up if it were rotated 90 degrees about another point.
com.vividsolutions.jts.geom.Coordinate	transform(com.vividsolutions.jts.geom.Coordinate c) Applies the affine transform to a point.

Methods inherited from class com.vividsolutions.jump.warp.CoordinateTransform

transform, transform

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AffineTransform

public AffineTransform(com.vividsolutions.jts.geom.Coordinate p1,
               com.vividsolutions.jts.geom.Coordinate p1_)

A transformation that maps p1 to p1_ via a translation (no rotation or shear).

Parameters:

p1 - a point

p1_ - the point it maps to

AffineTransform

public AffineTransform(com.vividsolutions.jts.geom.Coordinate p1,
               com.vividsolutions.jts.geom.Coordinate p1_,
               com.vividsolutions.jts.geom.Coordinate p2,
               com.vividsolutions.jts.geom.Coordinate p2_)

A transformation that maps p1 to p1_ and p2 to p2_ via a translation, rotation, and scaling (no "relative" shear).

Parameters:

p1 - a point

p1_ - the point p1 maps to

p2 - another point

p2_ - the point p2 maps to

AffineTransform

public AffineTransform(com.vividsolutions.jts.geom.Coordinate p1,
               com.vividsolutions.jts.geom.Coordinate p1_,
               com.vividsolutions.jts.geom.Coordinate p2,
               com.vividsolutions.jts.geom.Coordinate p2_,
               com.vividsolutions.jts.geom.Coordinate p3,
               com.vividsolutions.jts.geom.Coordinate p3_)

A transformation that maps p1 to p1_, p2 to p2_ and p3 to p3_.

Parameters:

p1 - a point

p1_ - the point p1 maps to

p2 - another point

p2_ - the point p2 maps to

p3 - another point

p3_ - the point p3 maps to

Method Detail

rotate90

public static com.vividsolutions.jts.geom.Coordinate rotate90(com.vividsolutions.jts.geom.Coordinate a,
                                              com.vividsolutions.jts.geom.Coordinate b)

Determines where a point would end up if it were rotated 90 degrees about another point.

Parameters:

a - the fixed point

b - the point to rotate (b itself will not be changed)

Returns:

b rotated 90 degrees clockwise about a

transform

public com.vividsolutions.jts.geom.Coordinate transform(com.vividsolutions.jts.geom.Coordinate c)

Applies the affine transform to a point. From http://graphics.lcs.mit.edu/classes/6.837/F01/Lecture07/lecture07.pdf:

      [ x_ ] = [  a11 a12 a13  ] [ x ]
      [ y_ ] = [  a21 a22 a23  ] [ y ]
      [ 1  ] = [  0   0   1    ] [ 1 ]
 

Specified by:

transform in class CoordinateTransform

Parameters:

c - the input to the affine transform

Returns:

the result of applying the affine transform to c