aff3_multiply.dart

/// Print the calculation which multiplies two 3x4 affine transformation
/// matrices.
///
/// The matrices store their elements in a flat array in column order.
void main() {
  StringBuffer buffer = new StringBuffer();
  String l = "a1";
  String r = "a2";
  for (int col in new Iterable.generate(4)) {
    for (int row in new Iterable.generate(3)) {
      buffer.writeAll([
        "$l[${0 + row}]*$r[${col * 3 + 0}]",
        "$l[${3 + row}]*$r[${col * 3 + 1}]",
        "$l[${6 + row}]*$r[${col * 3 + 2}]",
      ], " + ");
      if (3 == col) {
        buffer.write(" + $l[${9 + row}]");
      }
      buffer.write(",\n");
    }
  }
  print(buffer.toString());
}

/*
a1[0]*a2[0] + a1[3]*a2[1] + a1[6]*a2[2],
a1[1]*a2[0] + a1[4]*a2[1] + a1[7]*a2[2],
a1[2]*a2[0] + a1[5]*a2[1] + a1[8]*a2[2],
a1[0]*a2[3] + a1[3]*a2[4] + a1[6]*a2[5],
a1[1]*a2[3] + a1[4]*a2[4] + a1[7]*a2[5],
a1[2]*a2[3] + a1[5]*a2[4] + a1[8]*a2[5],
a1[0]*a2[6] + a1[3]*a2[7] + a1[6]*a2[8],
a1[1]*a2[6] + a1[4]*a2[7] + a1[7]*a2[8],
a1[2]*a2[6] + a1[5]*a2[7] + a1[8]*a2[8],
a1[0]*a2[9] + a1[3]*a2[10] + a1[6]*a2[11] + a1[9],
a1[1]*a2[9] + a1[4]*a2[10] + a1[7]*a2[11] + a1[10],
a1[2]*a2[9] + a1[5]*a2[10] + a1[8]*a2[11] + a1[11],
*/