RelAngle2D(PA, PB: TPoint2D): Real;
begin
RelAngle2D := Angle2D(Point2D(PB.X - PA.X, PB.Y - PA.Y));
end;

function RelDist2D(PA, PB: TPoint2D): Real;
begin
Result := Dist2D(Point2D(PB.X - PA.X, PB.Y - PA.Y));
end;

function RelDist3D(PA, PB: TPoint3D): Real;
begin
RelDist3D := Dist3D(Point3D(PB.X - PA.X, PB.Y - PA.Y, PB.Z - PA.Z));
end;

procedure Rotate2D(var P: TPoint2D; Angle2D: Real);
var
Temp: TPoint2D;
begin
Temp.X := P.X * Cos(Angle2D) - P.Y * Sin(Angle2D);
Temp.Y := P.X * Sin(Angle2D) + P.Y * Cos(Angle2D);
P := Temp;
end;

procedure RelRotate2D(var P: TPoint2D; PCentr: TPoint2D; Angle2D: Real);
var
Temp: TPoint2D;
begin
Temp := SubPoints(P, PCentr);
Rotate2D(Temp, Angle2D);
P := AddPoints(Temp, PCentr);
end;

procedure Move2D(var P: TPoint2D; Angle2D, Distance: Real);
var
Temp: TPoint2D;
begin
Temp.X := P.X + (Cos(Angle2D) * Distance);
Temp.Y := P.Y + (Sin(Angle2D) * Distance);
P := Temp;
end;

function Between(PA, PB: TPoint2D; Preference: Real): TPoint2D;
begin
Between.X := PA.X * Preference + PB.X * (1 - Preference);
Between.Y := PA.Y * Preference + PB.Y * (1 - Preference);
end;

function DistLine(A, B, C: Real; P: TPoint2D): Real;
begin
Result := (A * P.X + B * P.Y + C) / Sqrt(Sqr(A) + Sqr(B));
end;

function Dist2P(P, P1, P2: TPoint2D): Real;
begin
Result := DistLine(P1.Y - P2.Y, P2.X - P1.X, -P1.Y * P2.X + P1.X * P2.Y, P);
end;

function DistD1P(DX, DY: Real; P1, P: TPoint2D): Real;
begin
Result := DistLine(DY, -DX, -DY * P1.X + DX * P1.Y, P);
end;

function NearLine2P(P, P1, P2: TPoint2D; D: Real): Boolean;
begin
Result := False;
if DistD1P(-(P2.Y - P1.Y), P2.X - P1.X, P1, P) * DistD1P(-(P2.Y - P1.Y), P2.X - P1.X, P2, P) <= 0 then
if Abs(Dist2P(P, P1, P2)) < D then Result := True;
end;

function AddPoints(P1, P2: TPoint2D): TPoint2D;
begin
AddPoints := Point2D(P1.X + P2.X, P1.Y + P2.Y);
end;

function SubPoints(P1, P2: TPoint2D): TPoint2D;
begin
SubPoints := Point2D(P1.X - P2.X, P1.Y - P2.Y);
end;

function Invert(Col: TColor): TColor;
begin
Invert := not Col;
end;

function Dark(Col: TColor; Percentage: Byte): TColor;
var
R, G, B: Byte;
begin
R := GetRValue(Col); G := GetGValue(Col); B := GetBValue(Col);
R := Round(R * Percentage / 100);
G := Round(G * Percentage / 100);
B := Round(B * Percentage / 100);
Dark := RGB(R, G, B);
end;

function Light(Col: TColor; Percentage: Byte): TColor;
var
R, G, B: Byte;
begin
R := GetRValue(Col); G := GetGValue(Col); B := GetBValue(Col);
R := Round(R * Percentage / 100) + Round(255 - Percentage / 100 * 255);
G := Round(G * Percentage / 100) + Round(255 - Percentage / 100 * 255);
B := Round(B * Percentage / 100) + Round(255 - Percentage / 100 * 255);
Light := RGB(R, G, B);
end;

function Mix(Col1, Col2: TColor; Percentage: Byte): TColor;
var
R, G, B: Byte;
begin
R := Round((GetRValue(Col1) * Percentage / 100) + (GetRValue(Col2) * (100 - Percentage) / 100));
G := Round((GetGValue(Col1) * Percentage / 100) + (GetGValue(Col2) * (100 - Percentage) / 100));
B := Round((GetBValue(Col1) * Percentage / 100) + (GetB