line.divideAt(t)

Divide the line into two lines at the point that lies t (normalized length) away from the beginning of the line.

Returns an array with two new lines without modifying the original line. For example, if t equals 0.5, the function returns an array of two lines that subdivide the original line at its midpoint.

The function expects t to lie between 0 and 1; values outside the range are constrained to 0 and 1, respectively.