# [name]

A geometric line segment represented by a start and end point.

## Constructor

### [name]( [param:Vector3 start], [param:Vector3 end] )

[page:Vector3 start] - Start of the line segment. Default is (0, 0, 0).
[page:Vector3 end] - End of the line segment. Default is (0, 0, 0).
Creates a new [name].

## Properties

### [property:Vector3 start]

[page:Vector3] representing the start point of the line.

### [property:Vector3 end]

[page:Vector3] representing the end point of the line.

## Methods

### [method:Line3 applyMatrix4]( [param:Matrix4 matrix] )

Applies a matrix transform to the line segment.

### [method:Vector3 at]( [param:Float t], [param:Vector3 target] )

[page:Float t] - Use values 0-1 to return a position along the line segment.
[page:Vector3 target] — the result will be copied into this Vector3.
Returns a vector at a certain position along the line. When [page:Float t] = 0, it returns the start vector, and when [page:Float t] = 1 it returns the end vector.

### [method:Line3 clone]()

Returns a new [page:Line3] with the same [page:.start start] and [page:.end end] vectors as this one.

### [method:Vector3 closestPointToPoint]( [param:Vector3 point], [param:Boolean clampToLine], [param:Vector3 target] )

[page:Vector3 point] - return the closest point on the line to this point.
[page:Boolean clampToLine] - whether to clamp the returned value to the line segment.
[page:Vector3 target] — the result will be copied into this Vector3.
Returns the closets point on the line. If [page:Boolean clampToLine] is true, then the returned value will be clamped to the line segment.

### [method:Float closestPointToPointParameter]( [param:Vector3 point], [param:Boolean clampToLine] )

[page:Vector3 point] - the point for which to return a point parameter.
[page:Boolean clampToLine] - Whether to clamp the result to the range [0, 1].
Returns a point parameter based on the closest point as projected on the line segement. If [page:Boolean clampToLine] is true, then the returned value will be between 0 and 1.

### [method:Line3 copy]( [param:Line3 line] )

Copies the passed line's [page:.start start] and [page:.end end] vectors to this line.

### [method:Vector3 delta]( [param:Vector3 target] )

[page:Vector3 target] — the result will be copied into this Vector3.
Returns the delta vector of the line segment ( [page:.end end] vector minus the [page:.start start] vector).

### [method:Float distance]()

Returns the [link:https://en.wikipedia.org/wiki/Euclidean_distance Euclidean distance] (straight-line distance) between the line's [page:.start start] and [page:.end end] points.

### [method:Float distanceSq]()

Returns the square of the [link:https://en.wikipedia.org/wiki/Euclidean_distance Euclidean distance] (straight-line distance) between the line's [page:.start start] and [page:.end end] vectors.

### [method:Boolean equals]( [param:Line3 line] )

[page:Line3 line] - [page:Line3] to compare with this one.
Returns true if both line's [page:.start start] and [page:.end en] points are equal.

### [method:Vector3 getCenter]( [param:Vector3 target] )

[page:Vector3 target] — the result will be copied into this Vector3.
Returns the center of the line segment.

### [method:Line3 set]( [param:Vector3 start], [param:Vector3 end] )

[page:Vector3 start] - set the [page:.start start point] of the line.
[page:Vector3 end] - set the [page:.end end point] of the line.
Sets the start and end values by copying the provided vectors.

## Source

[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]