float hScale = (flipH ? -1 : 1);
float vScale = (flipV ? -1 : 1);
Vector3 scaleVector = new Vector3(hScale, vScale,1 );

Matrix4x4 scaleMatrix = Matrix4x4.TRS(Vector3.zero, Quaternion.identity, scaleVector );
Matrix4x4 offsetMatrix = Matrix4x4.TRS(new Vector3(-pos.x,-pos.y,0), Quaternion.identity, Vector3.one );
Matrix4x4 rotationMatrix = Matrix4x4.TRS(Vector3.zero, Quaternion.Euler(0,0,angle), Vector3.one );
Matrix4x4 offsetBackMatrix = Matrix4x4.TRS(new Vector3(pos.x,pos.y,0), Quaternion.identity, Vector3.one );

matrix = offsetBackMatrix * rotationMatrix * offsetMatrix * scaleMatrix;