function Intersect(const x1, y1, x2, y2, x3, y3, x4, y4: Double): Boolean;
var
UpperX: Double;
UpperY: Double;
LowerX: Double;
LowerY: Double;
Ax: Double;
Bx: Double;
Cx: Double;
Ay: Double;
By: Double;
Cy: Double;
D: Double;
F: Double;
E: Double;
begin
Result := False;
Ax := x2 - x1;
Bx := x3 - x4;
if Ax < 0.0 then
begin
LowerX := x2;
UpperX := x1;
end
else
begin
UpperX := x2;
LowerX := x1;
end;
if Bx > 0.0 then
begin
if (UpperX < x4) or (x3 < LowerX) then
Exit;
end
else if (Upperx < x3) or (x4 < LowerX) then
Exit;
Ay := y2 - y1;
By := y3 - y4;
if Ay < 0.0 then
begin
LowerY := y2;
UpperY := y1;
end
else
begin
UpperY := y2;
LowerY := y1;
end;
if By > 0.0 then
begin
if (UpperY < y4) or (y3 < LowerY) then
Exit;
end
else if (UpperY < y3) or (y4 < LowerY) then
Exit;
Cx := x1 - x3;
Cy := y1 - y3;
d := (By * Cx) - (Bx * Cy);
f := (Ay * Bx) - (Ax * By);
if f > 0.0 then
begin
if (d < 0.0) or (d > f) then
Exit;
end
else if (d > 0.0) or (d < f) then
Exit;
e := (Ax * Cy) - (Ay * Cx);
if f > 0.0 then
begin
if (e < 0.0) or (e > f) then
Exit;
end
else if (e > 0.0) or (e < f) then
Exit;
Result := True;
(*
Simple method, yet not so accurate for certain situations and a little more
inefficient (roughly 19.5%).
Result := (
((Orientation(x1,y1, x2,y2, x3,y3) * Orientation(x1,y1, x2,y2, x4,y4)) <= 0) and
((Orientation(x3,y3, x4,y4, x1,y1) * Orientation(x3,y3, x4,y4, x2,y2)) <= 0)
);
*)
end;
(* End of SegmentIntersect *)
|
