main/src/georegression/metric/Distance2D_F64.java
public static double distanceSq( LineSegment2D_F64 line, Point2D_F64 p ) {
		double a = line.b.x - line.a.x;
		double b = line.b.y - line.a.y;

		double t = a * ( p.x - line.a.x ) + b * ( p.y - line.a.y );
		t /= ( a * a + b * b );

		// if the point of intersection is past the end points return the distance
		// from the closest end point
		if( t < 0 ) {
			return UtilPoint2D_F64.distanceSq(line.a.x, line.a.y, p.x, p.y);
		} else if( t > 1.0 )
			return UtilPoint2D_F64.distanceSq(line.b.x, line.b.y, p.x, p.y);

		// return the distance of the closest point on the line
		return UtilPoint2D_F64.distanceSq(line.a.x + t * a, line.a.y + t * b, p.x, p.y);
	}
public static double distanceSq( LineSegment2D_F64 line, Point2D_F64 p ) {
		double a = line.b.x - line.a.x;
		double b = line.b.y - line.a.y;

		double t = a * ( p.x - line.a.x ) + b * ( p.y - line.a.y );
		t /= ( a * a + b * b );

		// if the point of intersection is past the end points return the distance
		// from the closest end point
		if( t < 0 ) {
			return UtilPoint2D_F64.distanceSq(line.a.x, line.a.y, p.x, p.y);
		} else if( t > 1.0 )
			return UtilPoint2D_F64.distanceSq(line.b.x, line.b.y, p.x, p.y);

		// return the distance of the closest point on the line
		return UtilPoint2D_F64.distanceSq(line.a.x + t * a, line.a.y + t * b, p.x, p.y);
	}
public static double distanceSq ( LineSegment2D_F64 line , Point2D_F64 p ) { double a = line . b . x - line . a . x ; double b = line . b . y - line . a . y ; double t = a * ( p . x - line . a . x ) + b * ( p . y - line . a . y ) ; t /= ( a * a + b * b ) ; // if the point of intersection is past the end points return the distance // from the closest end point if ( t < 0 ) { return UtilPoint2D_F64 . distanceSq ( line . a . x , line . a . y , p . x , p . y ) ; } else if ( t > 1.0 ) return UtilPoint2D_F64 . distanceSq ( line . b . x , line . b . y , p . x , p . y ) ; // return the distance of the closest point on the line return UtilPoint2D_F64 . distanceSq ( line . a . x + t * a , line . a . y + t * b , p . x , p . y ) ; }
<p>
Returns the Euclidean distance squared of the closest point on a line segment to the specified point.
</p>

@param line A line segment. Not modified.
@param p The point. Not modified.
@return Euclidean distance squared of the closest point on a line is away from a point.
<p > Returns the Euclidean distance squared of the closest point on a line segment to the specified point . < / p >