    curve.lengthAtT(t [, opt])

Return the length of the curve up to the point specified by `t`.

The curve is divided at `t` and the length of the first subcurve is returned. For more information about curve length calculation refer to `curve.length()` documentation.

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

This method does make use of the `opt.subdivisions` property.