`curve.closestPointTangent(point [, opt])`

Return a line that is tangent to the curve at the point that lies closest to `point`

.

The tangent line starts at the identified closest point. The direction from `start`

to `end`

is the same as the direction of the curve at the closest point.

If the control points of the curve all lie at the same coordinates, `null`

is returned (it is impossible to determine the slope of a point). The `curve.isDifferentiable()`

function may be used in advance to determine whether tangents can exist for a given curve.

The function uses the same algorithm as the `curve.closestPointT()`

function. The tangent at `t`

closest to `point`

is returned.

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.