    curve.closestPointT(point [, opt])

Return the `t` value of the point on the curve that lies closest to `point`.

The curve is first subdivided, according to `opt.precision` (refer to `curve.length()` documentation for more information about precision and curve flattening). Then, one subdivision is identified whose endpoints are the closest to `point`. A binary search is then performed on that subdivision, until a curve is found whose diffrence between endpoints' distance to `point` lies within `opt.precision`. The `t` value of the closest endpoint is returned by the function.

The default value for `opt.precision` is 3; this corresponds to maximum observed error of 0.1%.

The `opt.subdivisions` property may be specified, directly providing an array of pre-computed curve subdivisions with which to begin the algorithm. Use the `curve.getSubdivisions()` function to obtain an array of curve subdivisions. The `opt.precision` property is still necessary, however; it determines the precision of the point search algorithm.