transformation-matrix/src/transform.js

2d transformation matrix functions written in ES6 syntax. Tree shaking ready!

/**
 * Merge multiple matrices into one
 * @param matrices {...Matrix | Matrix[]} Matrices listed as separate parameters or in an array
 * @returns {Matrix} Affine Matrix
 */
export function transform (...matrices) {
  matrices = Array.isArray(matrices[0]) ? matrices[0] : matrices

  const multiply = (m1, m2) => {
    return {
      a: m1.a * m2.a + m1.c * m2.b,
      c: m1.a * m2.c + m1.c * m2.d,
      e: m1.a * m2.e + m1.c * m2.f + m1.e,
      b: m1.b * m2.a + m1.d * m2.b,
      d: m1.b * m2.c + m1.d * m2.d,
      f: m1.b * m2.e + m1.d * m2.f + m1.f
    }
  }

  switch (matrices.length) {
    case 0:
      throw new Error('no matrices provided')

    case 1:
      return matrices[0]

    case 2:
      return multiply(matrices[0], matrices[1])

    default: {
      const [m1, m2, ...rest] = matrices
      const m = multiply(m1, m2)
      return transform(m, ...rest)
    }
  }
}

/**
 * Merge multiple matrices into one
 * @param matrices {...Matrix | Matrix[]} Matrices listed as separate parameters or in an array
 * @returns {Matrix} Affine Matrix
 */
export function compose (...matrices) {
  return transform(...matrices)
}