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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4 (Public License)
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Anti-Grain Geometry - Version 2.4 Release Milano 3 (AggPas 2.4 RM3)
// Pascal Port By: Milan Marusinec alias Milano
// milan@marusinec.sk
// http://www.aggpas.org
// Copyright (c) 2005-2006
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//
//----------------------------------------------------------------------------
//
// class ellipse
//
// [Pascal Port History] -----------------------------------------------------
//
// 18.12.2005-Milano: Unit port establishment
//
{ agg_ellipse.pas }
unit
agg_ellipse ;
INTERFACE
{$I agg_mode.inc }
uses
Math ,
agg_basics ,
agg_vertex_source ;
{ TYPES DEFINITION }
type
ellipse_ptr = ^ellipse;
ellipse = object(vertex_source )
m_x ,
m_y ,
m_rx ,
m_ry ,
m_scale : double;
m_num ,
m_step : unsigned;
m_cw : boolean;
constructor Construct; overload;
constructor Construct(x ,y ,rx ,ry : double; num_steps : unsigned = 0; cw : boolean = false ); overload;
procedure init(x ,y ,rx ,ry : double; num_steps : unsigned = 0; cw : boolean = false );
procedure approximation_scale_(scale : double );
procedure rewind(path_id : unsigned ); virtual;
function vertex(x ,y : double_ptr ) : unsigned; virtual;
procedure calc_num_steps;
end;
{ GLOBAL PROCEDURES }
IMPLEMENTATION
{ LOCAL VARIABLES & CONSTANTS }
{ UNIT IMPLEMENTATION }
{ CONSTRUCT }
constructor ellipse.Construct;
begin
inherited Construct;
m_x :=0.0;
m_y :=0.0;
m_rx:=1.0;
m_ry:=1.0;
m_scale:=1.0;
m_num :=4;
m_step:=0;
m_cw :=false;
end;
{ CONSTRUCT }
constructor ellipse.Construct(x ,y ,rx ,ry : double; num_steps : unsigned = 0; cw : boolean = false );
begin
inherited Construct;
m_x :=x;
m_y :=y;
m_rx:=rx;
m_ry:=ry;
m_scale:=1.0;
m_num :=num_steps;
m_step:=0;
m_cw :=cw;
if m_num = 0 then
calc_num_steps;
end;
{ INIT }
procedure ellipse.init;
begin
m_x :=x;
m_y :=y;
m_rx:=rx;
m_ry:=ry;
m_num :=num_steps;
m_step:=0;
m_cw :=cw;
if m_num = 0 then
calc_num_steps;
end;
{ APPROXIMATION_SCALE_ }
procedure ellipse.approximation_scale_;
begin
m_scale:=scale;
calc_num_steps;
end;
{ REWIND }
procedure ellipse.rewind;
begin
m_step:=0;
end;
{ VERTEX }
function ellipse.vertex;
var
angle : double;
begin
if m_step = m_num then
begin
inc(m_step );
result:=path_cmd_end_poly or path_flags_close or path_flags_ccw;
exit;
end;
if m_step > m_num then
begin
result:=path_cmd_stop;
exit;
end;
angle:=m_step / m_num * 2.0 * pi;
if m_cw then
angle:=2.0 * pi - angle;
x^:=m_x + Cos(angle ) * m_rx;
y^:=m_y + Sin(angle ) * m_ry;
inc(m_step );
if m_step = 1 then
result:=path_cmd_move_to
else
result:=path_cmd_line_to;
end;
{ CALC_NUM_STEPS }
procedure ellipse.calc_num_steps;
var
ra ,
da : double;
begin
ra:=(Abs(m_rx ) + Abs(m_ry ) ) / 2;
da:=ArcCos(ra / (ra + 0.125 / m_scale ) ) * 2;
m_num:=trunc(2 * pi / da );
end;
END.
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