Not yet publishing this, but wanted to archive some experimental code.

Type Declaration

export declare interface Vector2 {
  x: number;
  y: number;
}

export declare interface Vector3 {
  x: number;
  y: number;
  z: number;
}

export declare type Matrix2D = [
  number, number,
  number, number,
  number, number,
];

export declare type Matrix3D = [
  number, number, number, number,
  number, number, number, number,
  number, number, number, number,
  number, number, number, number,
];

export declare type Matrix = Matrix2D | Matrix3D;

/**
 * Apply a transformation matrix to a point.
 * @param matrix A `number[]` with length 6 or 16.
 * @param vector An `object` with `x` and `y` properties.
 */
export declare function transformVector2(matrix: Matrix, vector: Vector2): Vector2

/**
 * Apply a transformation matrix to a point.
 * @param matrix A `number[]` with length 6 or 16.
 * @param vector An `object` with `x`, `y` and `z` properties.
 */
export declare function transformVector3(matrix: Matrix, vector: Vector3): Vector3

Implementation

export function transformVector2(matrix, vector) {
  let fm = format(matrix)
  if ('x' in vector && 'y' in vector) {
    let t = fm[3] * vector.x + fm[7] * vector.y + fm[15]

    return Object.assign({}, vector, {
      x: (fm[0] * vector.x + fm[4] * vector.y + fm[12]) / t,
      y: (fm[1] * vector.x + fm[5] * vector.y + fm[13]) / t,
    })
  }
  throw new TypeError('Expected object with `x` and `y` properties.')
}

export function transformVector3(matrix, vector) {
  let fm = format(matrix)
  if ('x' in vector && 'y' in vector && 'z' in vector) {
    let t = fm[3] * vector.x + fm[7] * vector.y + fm[11] * vector.z + fm[15]

    return Object.assign({}, vector, {
      x: (fm[0] * vector.x + fm[4] * vector.y + fm[8] * vector.z + fm[12]) / t,
      y: (fm[1] * vector.x + fm[5] * vector.y + fm[9] * vector.z + fm[13]) / t,
      z: (fm[2] * vector.x + fm[6] * vector.y + fm[10] * vector.z + fm[14]) / t,
    })
  }
  throw new TypeError('Expected object with `x`, `y` and `z` properties.')
}

Note: Use of Object.assign() breaks IE10 and IE11 support.

Apply Transforms to Vectors #8

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