function AngleRad(x1,y1,x2,y2:double):double;
begin
result:=ArcTan2(y2-y1,x2-x1);
end;
function AngleDeg(x1,y1,x2,y2:double):double;
begin
result:=RadToDeg(ArcTan2(y2-y1,x2-x1));
if result<0 then result:=360.0+result;
if result>=360.0 then result:=0;
end;