public static void Multiply(ref btMatrix3x3 m1, ref btMatrix3x3 m2, out btMatrix3x3 result) { result.el0.X = m2.tdotx(ref m1.el0); result.el0.Y = m2.tdoty(ref m1.el0); result.el0.Z = m2.tdotz(ref m1.el0); result.el0.W = 0; result.el1.X = m2.tdotx(ref m1.el1); result.el1.Y = m2.tdoty(ref m1.el1); result.el1.Z = m2.tdotz(ref m1.el1); result.el1.W = 0; result.el2.X = m2.tdotx(ref m1.el2); result.el2.Y = m2.tdoty(ref m1.el2); result.el2.Z = m2.tdotz(ref m1.el2); result.el2.W = 0; }