Mega Code Archive
Orientation in 3D of a point relative to a plane
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Title: Orientation in 3D of a point relative to a plane?
function Orientation(x1, y1, z1, x2, y2, z2, x3, y3, z3, Px, Py, Pz: Double): Integer;
var
Px1, Px2, Px3: Double;
Py1, Py2, Py3: Double;
Pz1, Pz2, Pz3: Double;
Orin: Double;
begin
Px1 := x1 - px;
Px2 := x2 - px;
Px3 := x3 - px;
Py1 := y1 - py;
Py2 := y2 - py;
Py3 := y3 - py;
Pz1 := z1 - pz;
Pz2 := z2 - pz;
Pz3 := z3 - pz;
Orin := Px1 * (Py2 * Pz3 - Pz2 * Py3) +
Px2 * (Py3 * Pz1 - Pz3 * Py1) +
Px3 * (Py1 * Pz2 - Pz1 * Py2);
if Orin then Result := -1 (* Orientaion is below plane *)
else if Orin 0.0 then Result :=
+1 (* Orientaion is above plane *)
else
Result := 0; (* Orientaion is coplanar to plane if result is 0 *)
end;
(* End Of Orientation *)
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