Mega Code Archive
Perpendicular distance from point to segment in 2d
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function PntToSegmentDistance(Px, Py, x1, y1, x2, y2: Double): Double;
var
Ratio: Double;
Dx: Double;
Dy: Double;
begin
if IsEqual(x1, x2) and IsEqual(y1, y2) then
begin
Result := Distance(Px, Py, x1, y1);
end
else
begin
Dx := x2 - x1;
Dy := y2 - y1;
Ratio := ((Px - x1) * Dx + (Py - y1) * Dy) / (Dx * Dx + Dy * Dy);
if Ratio < 0 then Result := Distance(Px, Py, x1, y1)
else if Ratio > 1 then Result := Distance(Px, Py, x2, y2)
else
Result := Distance(Px, Py, (1 - Ratio) * x1 + Ratio * x2,
(1 - Ratio) * y1 + Ratio * y2);
end;
end;
(* End PntToSegmentDistance *)
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