invert method

Matrix4 invert()

Implementation

Matrix4 invert() {
  // based on http://www.euclideanspace.com/maths/algebra/matrix/functions/inverse/fourD/index.htm
  var te = elements;
  final double n11 = te[0],
      n21 = te[1],
      n31 = te[2],
      n41 = te[3],
      n12 = te[4],
      n22 = te[5],
      n32 = te[6],
      n42 = te[7],
      n13 = te[8],
      n23 = te[9],
      n33 = te[10],
      n43 = te[11],
      n14 = te[12],
      n24 = te[13],
      n34 = te[14],
      n44 = te[15],
      t11 = n23 * n34 * n42 - n24 * n33 * n42 + n24 * n32 * n43 - n22 * n34 * n43 - n23 * n32 * n44 + n22 * n33 * n44,
      t12 = n14 * n33 * n42 - n13 * n34 * n42 - n14 * n32 * n43 + n12 * n34 * n43 + n13 * n32 * n44 - n12 * n33 * n44,
      t13 = n13 * n24 * n42 - n14 * n23 * n42 + n14 * n22 * n43 - n12 * n24 * n43 - n13 * n22 * n44 + n12 * n23 * n44,
      t14 = n14 * n23 * n32 - n13 * n24 * n32 - n14 * n22 * n33 + n12 * n24 * n33 + n13 * n22 * n34 - n12 * n23 * n34;

  final det = n11 * t11 + n21 * t12 + n31 * t13 + n41 * t14;

  if (det == 0) return set(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

  var detInv = 1 / det;

  te[0] = t11 * detInv;
  te[1] =
      (n24 * n33 * n41 - n23 * n34 * n41 - n24 * n31 * n43 + n21 * n34 * n43 + n23 * n31 * n44 - n21 * n33 * n44) *
          detInv;
  te[2] =
      (n22 * n34 * n41 - n24 * n32 * n41 + n24 * n31 * n42 - n21 * n34 * n42 - n22 * n31 * n44 + n21 * n32 * n44) *
          detInv;
  te[3] =
      (n23 * n32 * n41 - n22 * n33 * n41 - n23 * n31 * n42 + n21 * n33 * n42 + n22 * n31 * n43 - n21 * n32 * n43) *
          detInv;

  te[4] = t12 * detInv;
  te[5] =
      (n13 * n34 * n41 - n14 * n33 * n41 + n14 * n31 * n43 - n11 * n34 * n43 - n13 * n31 * n44 + n11 * n33 * n44) *
          detInv;
  te[6] =
      (n14 * n32 * n41 - n12 * n34 * n41 - n14 * n31 * n42 + n11 * n34 * n42 + n12 * n31 * n44 - n11 * n32 * n44) *
          detInv;
  te[7] =
      (n12 * n33 * n41 - n13 * n32 * n41 + n13 * n31 * n42 - n11 * n33 * n42 - n12 * n31 * n43 + n11 * n32 * n43) *
          detInv;

  te[8] = t13 * detInv;
  te[9] =
      (n14 * n23 * n41 - n13 * n24 * n41 - n14 * n21 * n43 + n11 * n24 * n43 + n13 * n21 * n44 - n11 * n23 * n44) *
          detInv;
  te[10] =
      (n12 * n24 * n41 - n14 * n22 * n41 + n14 * n21 * n42 - n11 * n24 * n42 - n12 * n21 * n44 + n11 * n22 * n44) *
          detInv;
  te[11] =
      (n13 * n22 * n41 - n12 * n23 * n41 - n13 * n21 * n42 + n11 * n23 * n42 + n12 * n21 * n43 - n11 * n22 * n43) *
          detInv;

  te[12] = t14 * detInv;
  te[13] =
      (n13 * n24 * n31 - n14 * n23 * n31 + n14 * n21 * n33 - n11 * n24 * n33 - n13 * n21 * n34 + n11 * n23 * n34) *
          detInv;
  te[14] =
      (n14 * n22 * n31 - n12 * n24 * n31 - n14 * n21 * n32 + n11 * n24 * n32 + n12 * n21 * n34 - n11 * n22 * n34) *
          detInv;
  te[15] =
      (n12 * n23 * n31 - n13 * n22 * n31 + n13 * n21 * n32 - n11 * n23 * n32 - n12 * n21 * n33 + n11 * n22 * n33) *
          detInv;

  return this;
}