multiply function

List<double> multiply(List<double> out, List<double> a, List<double> b)

Multiplies two mat4s

@param {mat4} out the receiving matrix @param {ReadonlyMat4} a the first operand @param {ReadonlyMat4} b the second operand @returns {mat4} out

Implementation

List<double> multiply(List<double> out, List<double> a, List<double> b) {
  final a00 = a[0], a01 = a[1], a02 = a[2], a03 = a[3];
  final a10 = a[4], a11 = a[5], a12 = a[6], a13 = a[7];
  final a20 = a[8], a21 = a[9], a22 = a[10], a23 = a[11];
  final a30 = a[12], a31 = a[13], a32 = a[14], a33 = a[15];

  // Cache only the current line of the second matrix
  double b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3];
  out[0] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
  out[1] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
  out[2] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
  out[3] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;

  b0 = b[4];
  b1 = b[5];
  b2 = b[6];
  b3 = b[7];
  out[4] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
  out[5] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
  out[6] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
  out[7] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;

  b0 = b[8];
  b1 = b[9];
  b2 = b[10];
  b3 = b[11];
  out[8] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
  out[9] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
  out[10] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
  out[11] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;

  b0 = b[12];
  b1 = b[13];
  b2 = b[14];
  b3 = b[15];
  out[12] = b0 * a00 + b1 * a10 + b2 * a20 + b3 * a30;
  out[13] = b0 * a01 + b1 * a11 + b2 * a21 + b3 * a31;
  out[14] = b0 * a02 + b1 * a12 + b2 * a22 + b3 * a32;
  out[15] = b0 * a03 + b1 * a13 + b2 * a23 + b3 * a33;
  return out;
}