<!-- AVATAR-FORGE · part 30 -->
this.direction.copy( ray.direction );

		return this;

	}

	at( t, target ) {

		return target.copy( this.origin ).addScaledVector( this.direction, t );

	}

	lookAt( v ) {

		this.direction.copy( v ).sub( this.origin ).normalize();

		return this;

	}

	recast( t ) {

		this.origin.copy( this.at( t, _vector$a ) );

		return this;

	}

	closestPointToPoint( point, target ) {

		target.subVectors( point, this.origin );

		const directionDistance = target.dot( this.direction );

		if ( directionDistance < 0 ) {

			return target.copy( this.origin );

		}

		return target.copy( this.origin ).addScaledVector( this.direction, directionDistance );

	}

	distanceToPoint( point ) {

		return Math.sqrt( this.distanceSqToPoint( point ) );

	}

	distanceSqToPoint( point ) {

		const directionDistance = _vector$a.subVectors( point, this.origin ).dot( this.direction );

		// point behind the ray

		if ( directionDistance < 0 ) {

			return this.origin.distanceToSquared( point );

		}

		_vector$a.copy( this.origin ).addScaledVector( this.direction, directionDistance );

		return _vector$a.distanceToSquared( point );

	}

	distanceSqToSegment( v0, v1, optionalPointOnRay, optionalPointOnSegment ) {

		// from https://github.com/pmjoniak/GeometricTools/blob/master/GTEngine/Include/Mathematics/GteDistRaySegment.h
		// It returns the min distance between the ray and the segment
		// defined by v0 and v1
		// It can also set two optional targets :
		// - The closest point on the ray
		// - The closest point on the segment

		_segCenter.copy( v0 ).add( v1 ).multiplyScalar( 0.5 );
		_segDir.copy( v1 ).sub( v0 ).normalize();
		_diff.copy( this.origin ).sub( _segCenter );

		const segExtent = v0.distanceTo( v1 ) * 0.5;
		const a01 = - this.direction.dot( _segDir );
		const b0 = _diff.dot( this.direction );
		const b1 = - _diff.dot( _segDir );
		const c = _diff.lengthSq();
		const det = Math.abs( 1 - a01 * a01 );
		let s0, s1, sqrDist, extDet;

		if ( det > 0 ) {

			// The ray and segment are not parallel.

			s0 = a01 * b1 - b0;
			s1 = a01 * b0 - b1;
			extDet = segExtent * det;

			if ( s0 >= 0 ) {

				if ( s1 >= - extDet ) {

					if ( s1 <= extDet ) {

						// region 0
						// Minimum at interior points of ray and segment.

						const invDet = 1 / det;
						s0 *= invDet;
						s1 *= invDet;
						sqrDist = s0 * ( s0 + a01 * s1 + 2 * b0 ) + s1 * ( a01 * s0 + s1 + 2 * b1 ) + c;

					} else {

						// region 1

						s1 = segExtent;
						s0 = Math.max( 0, - ( a01 * s1 + b0 ) );
						sqrDist = - s0 * s0 + s1 * ( s1 + 2 * b1 ) + c;

					}

				} else {

					// region 5

					s1 = - segExtent;
					s0 = Math.max( 0, - ( a01 * s1 + b0 ) );
					sqrDist = - s0 * s0 + s1 * ( s1 + 2 * b1 ) + c;

				}

			} else {

				if ( s1 <= - extDet ) {

					// region 4

					s0 = Math.max( 0, - ( - a01 * segExtent + b0 ) );
					s1 = ( s0 > 0 ) ? - segExtent : Math.min( Math.max( - segExtent, - b1 ), segExtent );
					sqrDist = - s0 * s0 + s1 * ( s1 + 2 * b1 ) + c;

				} else if ( s1 <= extDet ) {

					// region 3

					s0 = 0;
					s1 = Math.min( Math.max( - segExtent, - b1 ), segExtent );
					sqrDist = s1 * ( s1 + 2 * b1 ) + c;

				} else {

					// region 2

					s0 = Math.max( 0, - ( a01 * segExtent + b0 ) );
					s1 = ( s0 > 0 ) ? segExtent : Math.min( Math.max( - segExtent, - b1 ), segExtent );
					sqrDist = - s0 * s0 + s1 * ( s1 + 2 * b1 ) + c;

				}

			}

		} else {

			// Ray and segment are parallel.

			s1 = ( a01 > 0 ) ? - segExtent : segExtent;
			s0 = Math.max( 0, - ( a01 * s1 + b0 ) );
			sqrDist = - s0 * s0 + s1 * ( s1 + 2 * b1 ) + c;

		}

		if ( optionalPointOnRay ) {

			optionalPointOnRay.copy( this.origin ).addScaledVector( this.direction, s0 );

		}

		if ( optionalPointOnSegment ) {

			optionalPointOnSegment.copy( _segCenter ).addScaledVector( _segDir, s1 );

		}

		return sqrDist;

	}

	intersectSphere( sphere, target ) {

		_vector$a.subVectors( sphere.center, this.origin );
		const tca = _vector$a.dot( this.direction );
		const d2 = _vector$a.dot( _vector$a ) - tca * tca;
		const radius2 = sphere.radius * sphere.radius;

		if ( d2 > radius2 ) return null;

		const thc = Math.sqrt( radius2 - d2 );

		// t0 = first intersect point - entrance on front of sphere
		const t0 = tca - thc;

		// t1 = second intersect point - exit point on back of sphere
		const t1 = tca + thc;

		// test to see if t1 is behind the ray - if so, return null
		if ( t1 < 0 ) return null;

		// test to see if t0 is behind the ray:
		// if it is, the ray is inside the sphere, so return the second exit point scaled by t1,
		// in order to always return an intersect point that is in front of the ray.
		if ( t0 < 0 ) return this.at( t1, target );

		// else t0 is in front of the ray, so return the first collision point scaled by t0
		return this.at( t0, target );

	}

	intersectsSphere( sphere ) {

		return this.distanceSqToPoint( sphere.center ) <= ( sphere.radius * sphere.radius );

	}

	distance