transformist

Simple transformations in the plane. A transform in two dimensions is defined here as a translation, a rotation, and a scaling. This module lets you specify this kind of transform and apply it, or its inverse, to one or more points. Methods are also provided for composing transforms and exporting as a matrix. This is essentially wrapping mat3 transforms, but with an API that might seem friendlier. Useful for 2D games and graphics.

install

use npm

npm install transformist

examples

var transform = require('transformist')

var t = transform({translation: [1, 2], scale: 2})

t.apply([1, 1])
> [3, 4]

var t = transform({rotation: 90, scale: 2})

t.apply([[0, 0], [0, 1]])
> [[0, 0], [-2, 0]]

usage

t = transform(opts)

create a new transform

• opts.translation two-dimensional array in the form [x, y], default [0, 0]
• opts.rotation angle of rotation in degrees, default 0
• opts.scale scale factor, default 1

t.apply(points)

Apply transformation to one or more points of the form [[x, y], [x, y]...] or [x, y]. Applies in order: scale, rotation, translation.

t.invert(points)

Undo a transformation on one or more points of the form [[x, y], [x, y]...] or [x, y]. Applies the inverse transform in order: translation, rotation, scale.

t.compose(other)

Compose this transform with a transform other, modifies in place. Equivalent to multiplying 3d transformation matrices.

t.tomat()

Return a mat3 representation of the transform.