How to calculate an (Roll, Turn, Pitch) angle from two object?

[Roman]

Stupid question.
I can not calculate the angle.

I have 4 xyz points (A, B, C, D).
I create 3 object:
Obj1 = Point AB.
Obj2 = Point CD.

Obj3 = Сrossing Obj1, Obj2.
I need set Roll, Turn, Pitch angle to Obj3.

If Obj / Onj2 rotated one axis then works.
If Obj / Onj2 rotated two or three axes then not works.

http://i.imgur.com/ZyWnDyD.jpg

Help me please..

My very bad / stupid / wrong code:

        Obj3.RollAngle := Obj1.RollAngle;
        Obj3.PitchAngle := Obj2.PitchAngle;

        if Point1.x<Point2.x then
        Obj3.TurnAngle :=  Obj1.TurnAngle else
        Obj3.TurnAngle := -Obj1.TurnAngle;

        if Point1.y<Point2.y then Obj3.PitchAngle := -Obj3.PitchAngle;
        if Point3.x<Point4.x then Obj3.PitchAngle := -Obj3.PitchAngle;
        if Point3.y>Point4.y then Obj3.PitchAngle := -Obj3.PitchAngle;

[Jerome.D (BeanzMaster)]

Hi check in GLVectorGeometry unit you'll find what you search i think
cf :
function IsColinear(const V1, V2: TVector): Boolean;
function VectorAbs(const V: TVector): TVector;
function VectorRotateAroundX,Y,Z(const V: TAffineVector; alpha: Single) : TAffineVector;
function VectorPerpendicular(const V, n: TAffineVector): TAffineVector;
function VectorReflect(const V, n: TAffineVector): TAffineVector;
function AngleBetweenVectors(const a, b, ACenterPoint: TVector): Single;
ect ....

I think it exist a solution for calculating angle with the up and direction values but don't remember how to do and where i saw something similar.

[Roman]

I still can not with Vector functions :[

i set Obj3 parent := Obj1;
Then search TurnAngle.

This work:

ta:=0;
vd:=999999;
tvd:=999999;
tmpOBJ.Parent:=Obj3;
tmpOBJ.Position.SetPoint(0,0,0.8);
for i:=0 to 360 do
begin
  Obj3.TurnAngle:=i;
  tvd:=VectorDistance(tmpOBJ.AbsoluteAffinePosition,Obj2.AbsoluteAffinePosition);
  if vd>tvd then
  begin
    vd:=tvd;
    ta:=i;
  end;
end;
Obj3.TurnAngle:=ta;

BUT this crazy method :[

How to do the right thing?