public void IsValidTest()
{
var m = Matrix44F.CreateTranslation(1, 2, 3) * Matrix44F.CreateRotationY(0.1f) * Matrix44F.CreateScale(-2, 3, 4);
Assert.IsTrue(SrtTransform.IsValid(m));
// Concatenating to SRTs creates a skew.
m = Matrix44F.CreateRotationZ(0.1f) * Matrix44F.CreateScale(-2, 3, 4) * m;
Assert.IsFalse(SrtTransform.IsValid(m));
}