What is the difference between these ?

Questions & Answers
1

hey all,

i just wanted to know what is the difference between these | and ||

i know the double lines are Or what is the single ?

2

A single | or & is a bitwise operator, for binary-type math. For example 6 in binary is 110 and 12 in binary is 1100. 6|12 means to use all the bits in 6 OR in 12, which is 1110, or 14.

Layers are stored as binary, putting a 1 in the slot for that layer. Layer 0 is 00000001, layer 1 is 00000010 layer 2 is 00000100, and so on. This is why there are layers 0-31. Computer numbers are 32-bits long. A layer is always 31 zeros and a 1 in the slot for that layer.)

If layers were stored as normal numbers, and you wanted to skip 2, 3 and 6 for a raycast, you'd have to write `if(layer!=2 && layer!=3 && layer!=6)`. Instead, you write the layers you want to skip using the binary layer representation:

    76543210

  A 00001000    <-- I am on layer 3
  B 01001100    <-- skip layers are 6, 3 and 2
    --------    
A&B 00001000    <-- a 1 in slots where both are 1's
A|B 01001100    <-- a 1 in slots where either are 1's

Using `(layer&skipLayers)` very quickly checks whether the current layer is 2, 3 or 6 (a result of not 0 means you are in the skipLayers.)

If you using using 01001100 to represent skipping 6,3 and 2, and want to add layer 5, you can write: `skipLayers=skipLayers|(1<<5);` to get 01101100. The double-lessThan symbol is a bitshift. If means to turn 1 into 100000 by shifting it five spaces over.