The % and mod functions very quite a bit from language to language. The new mod function is a floored remainder operation, which is what Python would use, but JavaScript would not. It is very handy and works well with the way Pixelblaze treads cyclical values between 0-1.
From Wikipedia:
“[…] the remainder would have the same sign as the divisor . Due to the floor function, the quotient is always rounded downwards, even if it is already negative.”
The implementation is pretty simple. Using %, if the result has a sign that doesn’t equal the sign of the divisor, add the divisor to it.
function flooredMod(dividend, divisor) {
var res = dividend % divisor
if ((res != 0) && (res > 0) != (divisor > 0)) { //this compares the sign of both
res += divisor
}
return res
}
As you can see, they will only differ from % when there are negative numbers mixed with positive.
As a quick example, using the % operator if you take -1.2 % 1 you get -0.2. This makes sense if you think -1.2/1 == -1.2 == -1 + -0.2 so taking away the whole integer part, leaving -0.2 is the remainder.
Using mod on V3, or the equivalent flooredMod above gets you a different result. mod(-1.2, 1) results in 0.8 a positive number. This is very useful if you are trying to “wrap” a number between 0 and 1 (or some other range), and might end up with a negative number. This makes sense if you think about modulus math as a number line that wraps around in a circle with a circumference equal to the divisor. Imagine a circle with 0-360 degrees. Where is -45 degrees? 315 degrees! This is where the floored division modulus comes in handy: mod(-45, 360) == 315.