The sum
var accumulates the length of the pattern.
For example, on a line with a pattern of [10,10]
, the pattern will take 20 points to draw itself out (i.e. 10 + 10
or the sum of all the values in the pattern array).
In the example above, we are calculating the pattern where the dash lengths increase with gaps always equal to 10
.
So, to animate through the entire pattern we calculate the length / sum of the pattern.