Mega Code Archive
Determine the point at which two 2D segments intersect
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Title: Determine the point at which two 2D segments intersect?
procedure IntersectPoint(x1, y1, x2, y2, x3, y3, x4, y4: Double; var Nx, Ny: Double);
var
R: Double;
dx1, dx2, dx3: Double;
dy1, dy2, dy3: Double;
begin
dx1 := x2 - x1;
dx2 := x4 - x3;
dx3 := x1 - x3;
dy1 := y2 - y1;
dy2 := y1 - y3;
dy3 := y4 - y3;
R := dx1 * dy3 - dy1 * dx2;
if R 0 then
begin
R := (dy2 * (x4 - x3) - dx3 * dy3) / R;
Nx := x1 + R * dx1;
Ny := y1 + R * dy1;
end
else
begin
if Collinear(x1, y1, x2, y2, x3, y3) then
begin
Nx := x3;
Ny := y3;
end
else
begin
Nx := x4;
Ny := y4;
end;
end;
end;
function Collinear(x1, y1, x2, y2, x3, y3: Double): Boolean;
begin
Result := (((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) = 0);
end;
(* End Of Collinear *)
// calcule le point d'intersection de 2 droites bidimensionnelles
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