Class Transformation
JXG.Transformation
↳ Transformation
This element is used to provide projective transformations.
Defined in: transformation.js.
Extends
JXG.Transformation.
| Constructor Attributes | Constructor Name and Description |
|---|---|
|
Transformation(The)
A transformation consists of a 3x3 matrix, i.e.
|
- Methods borrowed from class JXG.Transformation:
- apply, applyOnce, bindTo, melt, setAttribute, setMatrix, setProperty, update
Class Detail
Transformation(The)
A transformation consists of a 3x3 matrix, i.e. it is a projective transformation.
- Parameters:
- {number|function} The
- parameters depend on the transformation type, supplied as attribute 'type'.
Possible transformation types are
- 'translate'
- 'scale'
- 'reflect'
- 'rotate'
- 'shear'
- 'generic'
Translation matrix:
( 1 0 0) ( z ) ( a 1 0) * ( x ) ( b 0 1) ( y )
Scale matrix:
( 1 0 0) ( z ) ( 0 a 0) * ( x ) ( 0 0 b) ( y )
A rotation matrix with angle a (in Radians)
( 1 0 0 ) ( z ) ( 0 cos(a) -sin(a)) * ( x ) ( 0 sin(a) cos(a) ) ( y )
Shear matrix:
( 1 0 0) ( z ) ( 0 1 a) * ( x ) ( 0 b 1) ( y )
Generic transformation:
( a b c ) ( z ) ( d e f ) * ( x ) ( g h i ) ( y )
- Throws:
- {Exception}
- If the element cannot be constructed with the given parent objects an exception is thrown.
- Examples:
// The point B is determined by taking twice the vector A from the origin
var p0 = board.create('point', [0, 3], {name: 'A'}),
t = board.create('transform', [function(){ return p0.X(); }, "Y(A)"], {type: 'translate'}),
p1 = board.create('point', [p0, t], {color: 'blue'});
// The point B is the result of scaling the point A with factor 2 in horizontal direction
// and with factor 0.5 in vertical direction.
var p1 = board.create('point', [1, 1]),
t = board.create('transform', [2, 0.5], {type: 'scale'}),
p2 = board.create('point', [p1, t], {color: 'blue'});
// The point B is rotated around C which gives point D. The angle is determined
// by the vertical height of point A.
var p0 = board.create('point', [0, 3], {name: 'A'}),
p1 = board.create('point', [1, 1]),
p2 = board.create('point', [2, 1], {name:'C', fixed: true}),
// angle, rotation center:
t = board.create('transform', ['Y(A)', p2], {type: 'rotate'}),
p3 = board.create('point', [p1, t], {color: 'blue'});
// A concatenation of several transformations.
var p1 = board.create('point', [1, 1]),
t1 = board.create('transform', [-2, -1], {type: 'translate'}),
t2 = board.create('transform', [Math.PI/4], {type: 'rotate'}),
t3 = board.create('transform', [2, 1], {type: 'translate'}),
p2 = board.create('point', [p1, [t1, t2, t3]], {color: 'blue'});
// Reflection of point A
var p1 = board.create('point', [1, 1]),
p2 = board.create('point', [1, 3]),
p3 = board.create('point', [-2, 0]),
l = board.create('line', [p2, p3]),
t = board.create('transform', [l], {type: 'reflect'}), // Possible are l, l.id, l.name
p4 = board.create('point', [p1, t], {color: 'blue'});
// One time application of a transform to points A, B
var p1 = board.create('point', [1, 1]),
p2 = board.create('point', [1, 1]),
t = board.create('transform', [3, 2], {type: 'shear'});
t.applyOnce([p1, p2]);
// Construct a square of side length 2 with the
// help of transformations
var sq = [],
right = board.create('transform', [2, 0], {type: 'translate'}),
up = board.create('transform', [0, 2], {type: 'translate'}),
pol, rot, p0;
// The first point is free
sq[0] = board.create('point', [0, 0], {name: 'Drag me'}),
// Construct the other free points by transformations
sq[1] = board.create('point', [sq[0], right]),
sq[2] = board.create('point', [sq[0], [right, up]]),
sq[3] = board.create('point', [sq[0], up]),
// Polygon through these four points
pol = board.create('polygon', sq, {
fillColor:'blue',
gradient:'radial',
gradientsecondcolor:'white',
gradientSecondOpacity:'0'
}),
p0 = board.create('point', [0, 3], {name: 'angle'}),
// Rotate the square around point sq[0] by dragging A
rot = board.create('transform', ['Y(angle)', sq[0]], {type: 'rotate'});
// Apply the rotation to all but the first point of the square
rot.bindTo(sq.slice(1));
Elements