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-- $Date: 2004/02/23 08:22:06 $
-- $Revision: 1.20 $
-- $Author: jcrocholl $
-- with Messages; use Messages;
package body Cubics is
-- Create a cubic bezier curve.
function Create
(To : in Vector; -- End point of the curve.
Control_A : in Vector; -- First control point of curve.
Control_B : in Vector) -- Second control point of curve.
return Line_Access is -- The newly created curve.
begin
return new Cubic'(To => To,
Control_A => Control_A,
Control_B => Control_B,
Length => 0.0);
end Create;
-- Calculate the arc length of this curve. Results are cached for
-- reuse. So make sure the starting point always remains the same
-- between calls.
function Length
(Start : in Vector; -- Starting point of the curve.
This : access Cubic) -- Get this curve's arc length.
return Real is -- The length of the arc.
begin
if This.Length = 0.0 then
This.Length := abs(This.To - Start);
end if;
return This.Length;
end Length;
-- Scale a curve by a given factor.
procedure Scale
(This : access Cubic; -- Scale this curve.
Factor : in Real) is -- Scaling factor.
begin
This.To := This.To * Factor;
This.Control_A := This.Control_A * Factor;
This.Control_B := This.Control_B * Factor;
This.Length := This.Length * Factor;
end Scale;
-- Translate a curve by a given offset.
procedure Translate
(This : access Cubic; -- Translate this curve.
Offset : in Vector) is -- Translating offset.
begin
This.To := This.To + Offset;
This.Control_A := This.Control_A + Offset;
This.Control_B := This.Control_B + Offset;
end Translate;
-- Get one point from the cubic bezier curve.
function Way_Point
(Start : in Vector; -- Starting point of the curve.
This : access Cubic; -- Definition of the curve.
Part : in Real) -- Parametrization variable from 0 to 1.
return Vector -- The point on the curve.
is
Part_1 : Real := 1.0 - Part;
begin
return Start * Cube(Part_1) +
This.Control_A * 3.0 * Square(Part_1) * Part +
This.Control_B * 3.0 * Part_1 * Square(Part) +
This.To * Cube(Part);
end Way_Point;
-- Format a cubic bezier curve for Scalable Vector Graphics output.
function To_SVG
(This : access Cubic; -- Format this curve.
Tolerance : in Real) -- Tolerance level.
return String is -- The resulting SVG code.
begin
return "C " &
To_String(This.Control_A, Tolerance) & " " &
To_String(This.Control_B, Tolerance) & " " &
To_String(This.To, Tolerance);
end To_SVG;
-- Format a cubic bezier curve for postscript output.
function To_Postscript
(This : access Cubic; -- Format this curve.
Tolerance : in Real) -- Tolerance level.
return String is -- The resulting Postscript code.
begin
return
To_String(Mirror_Y(This.Control_A), Tolerance) & " " &
To_String(Mirror_Y(This.Control_B), Tolerance) & " " &
To_String(Mirror_Y(This.To), Tolerance) & " curveto";
end To_Postscript;
end Cubics;