Hi,
I’m working with quaternions and I found a very nasty issue with quaternions. It appears that multiple compositions with null quaternions can yield invalid data. The members of the output quaternion will have a denormalized value (between absolute zero and the minimum float quantum), with a nice #DEN suffix in Visual Studio.
FQuat Test1 = FQuat::MakeFromEuler(FVector(0, 0, 0));
FQuat Test2 = FQuat::MakeFromEuler(FVector(0, 0, 0));
for (int i = 0; i < 100; i++)
{
FQuat Test3 = Test1 * Test2.Inverse();
Test1 = Test1 * Test3;
}
FRotator Debug(Test1.Rotator());
UE_LOG(LogFlare, Display, TEXT("%f %f %f"), Debug.Roll, Debug.Pitch, Debug.Yaw);
LogFlare:Display: 1.#QNAN0 -90.000000 -1.#IND00
Things get ugly after ~50 iterations. 10 is fine, 100 fails. Once one quaternion has failed, it will invalidate every other quaternion as well through math operations.
I understand that the above code can be seen as looking for trouble, but the above logic is actually in my game’s Tick and thus, less than 2 seconds worth of empty (yet valid) data will completely crash the logic.
Any thought?