#1
_PreDamage = 0.8; vehicle player setHitPointDamage ["hitEngine",_PreDamage + 0.1]; -> Engine turns off (Result: 0.9)
#2
_PreDamage = 0.8; vehicle player setHitPointDamage ["hitEngine",0.9]; <-- Engine stays on
Both have the same result, but react different.
Place an Offroad, get in, turn Engine on, Execute Script #1 -> Engine turns off
->
Vehicle player setDamage 0;
->
execute #2 -> Engine stays on.
Nothing is strange about it. This is Arma's Single precision floating point for you.
https://en.wikipedia.org/wiki/Single-precision_floating-point_format
hint str ((0.8 + 0.1) > 0.9) true
hint str ((0.8 + 0.1) - 0.9) 5.96046e-008
It is just that at == 0.9 engine still ok, at > 0.9 it is not