sorry for asking this question but I couldn't understand it
-- but i don't understand this code
ballDX = math.random(2) == 1 and 100 or -100
--here ballDY will give value between -50 to 50
ballDY = math.random(-50, 50)
I don't understand the structure what is (2) and why it's == 1
Thank you a lot
math.random(x) will randomly return an integer between 1 and x.
So math.random(2) will randomly return 1 or 2.
If it returns 1 (== 1), ballDX will be set to 100.
If it returns 2 (~= 1), ballDX will be set to -100.
A simple way to make a 50-50 chance.
That is a very common way of assigning variables in Lua based on conditionals. It’s the same you’d do, for example, in Python with “foo = a if x else b”: The first function, math.random(2), returns either 1 or 2. So, if it returns 1 the part math.random(2) == 1 is true and so you assign 100 to the variable ballDX. Otherwise, assign -100 to it.
In lua
result = condition and first or second
basically means the same as
if condition and first ~= nil and first ~= false then
result = first
else
result = second
end
So in your case
if math.random(2) == 1 then
ballDX = 100
else
ballDX = -100
end
in other words, there is a 50/50 chance for ballDX to become 100 or -100
For a better understanding, a look at lua documentation helps a lot : https://www.lua.org/pil/3.3.html
You can read: The operator or returns its first argument if it is not false; otherwise, it returns its second argument:
So if the random number is 1 it will return the first argument (100) of the "or" otherwise it will return the second argument (-100).
math.random() < 0.5.