Use of "|"

Hello !

In the charactere asset of Unity I saw :
m_Rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;

I don't known what "|" mean. Someone could explain it to me ?
Thank a lot

 

It's a bitwise 'OR' operator.
In the example is used for combining the enums.. some info here:
https://docs.unity3d.com/ScriptReference/RigidbodyConstraints.html

Here's 1 page with general info on bitwise operators: https://www.tutorialspoint.com/csharp/csharp_bitwise_operators.htm

Hopefully that helps

 

It's a bitwise "or" operation. To save space, that constraints variable is probably a single byte of information. To set it, you couldn't use a whole boolean, because that would set all 8 bits to either 1 or 0 (or some similar effect). So instead, each constraint is represented as a different bit of the 8 and they are logically combined.

For instance:
XRotation = 00000001
YRotation = 00000010
then
XRot|YRot = 00000011

meanwhile if it were a bit wise "and" operation
XRot&YRot = 00000000

A normal || or && operation works the same logic, but in an all or nothing manner.

So
11111110 || 00000010
is not guranteed to evaluate bitwise, and may result in 00000000 (false), just because both of the last bits were 0. Or, it may evaluate to 11111111 (true) due to either the first bit evaluating to 1, or because at least single bit evaluates to 1.

 

Thank you very much

thank you ! It's help me lot !

 

You cannot use a logical OR with integers in C#.

However, in c, for instance, 2 ints using a logical OR operator would evaluate to true if either was not zero.. no bits are modified, and the result is '1' or '0' (depending on any non-zero or both zeroes).

 

Glad I could help!