Method apply

src/math/Matrices/Matrix.js:823–878

* Applies a transformation matrix to the current matrix. * * This method multiplies the current matrix by another matrix, which can be provided * in several forms: another Matrix instance, an array representing a matrix, or as * individual arguments representing the elements of a 4x4 mat

(multMatrix)

   * }
   */
  apply(multMatrix) {
    let _src;

    if (multMatrix === this || multMatrix === this.matrix) {
      _src = this.copy().matrix; // only need to allocate in this rare case
    } else if (multMatrix instanceof Matrix) {
      _src = multMatrix.matrix;
    } else if (isMatrixArray(multMatrix)) {
      _src = multMatrix;
    } else if (arguments.length === 16) {
      _src = arguments;
    } else {
      return; // nothing to do.
    }

    const mat4 = this.matrix;

    // each row is used for the multiplier
    const m0 = mat4[0];
    const m4 = mat4[4];
    const m8 = mat4[8];
    const m12 = mat4[12];
    mat4[0] = _src[0] * m0 + _src[1] * m4 + _src[2] * m8 + _src[3] * m12;
    mat4[4] = _src[4] * m0 + _src[5] * m4 + _src[6] * m8 + _src[7] * m12;
    mat4[8] = _src[8] * m0 + _src[9] * m4 + _src[10] * m8 + _src[11] * m12;
    mat4[12] = _src[12] * m0 + _src[13] * m4 + _src[14] * m8 + _src[15] * m12;

    const m1 = mat4[1];
    const m5 = mat4[5];
    const m9 = mat4[9];
    const m13 = mat4[13];
    mat4[1] = _src[0] * m1 + _src[1] * m5 + _src[2] * m9 + _src[3] * m13;
    mat4[5] = _src[4] * m1 + _src[5] * m5 + _src[6] * m9 + _src[7] * m13;
    mat4[9] = _src[8] * m1 + _src[9] * m5 + _src[10] * m9 + _src[11] * m13;
    mat4[13] = _src[12] * m1 + _src[13] * m5 + _src[14] * m9 + _src[15] * m13;

    const m2 = mat4[2];
    const m6 = mat4[6];
    const m10 = mat4[10];
    const m14 = mat4[14];
    mat4[2] = _src[0] * m2 + _src[1] * m6 + _src[2] * m10 + _src[3] * m14;
    mat4[6] = _src[4] * m2 + _src[5] * m6 + _src[6] * m10 + _src[7] * m14;
    mat4[10] = _src[8] * m2 + _src[9] * m6 + _src[10] * m10 + _src[11] * m14;
    mat4[14] = _src[12] * m2 + _src[13] * m6 + _src[14] * m10 + _src[15] * m14;

    const m3 = mat4[3];
    const m7 = mat4[7];
    const m11 = mat4[11];
    const m15 = mat4[15];
    mat4[3] = _src[0] * m3 + _src[1] * m7 + _src[2] * m11 + _src[3] * m15;
    mat4[7] = _src[4] * m3 + _src[5] * m7 + _src[6] * m11 + _src[7] * m15;
    mat4[11] = _src[8] * m3 + _src[9] * m7 + _src[10] * m11 + _src[11] * m15;
    mat4[15] = _src[12] * m3 + _src[13] * m7 + _src[14] * m11 + _src[15] * m15;

    return this;
  }

  /**