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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
//
//----------------------------------------------------------------------------
//
// Arc vertex generator
//
// [Pascal Port History] -----------------------------------------------------
//
// 17.01.2006-Milano: Unit port establishment
//
{ agg_arc.pas }
unit
agg_arc ;
INTERFACE
{$I agg_mode.inc }
uses
Math ,
agg_basics ,
agg_vertex_source ;
{ TYPES DEFINITION }
type
arc = object(vertex_source )
m_x ,
m_y ,
m_rx ,
m_ry ,
m_angle ,
m_start ,
m_end ,
m_scale ,
m_da : double;
m_ccw ,
m_initialized : boolean;
m_path_cmd : unsigned;
constructor Construct; overload;
constructor Construct(x ,y ,rx ,ry ,a1 ,a2 : double; ccw : boolean = true ); overload;
procedure init(x ,y ,rx ,ry ,a1 ,a2 : double; ccw : boolean = true );
procedure approximation_scale_(s : double );
function _approximation_scale : double;
procedure rewind(path_id : unsigned ); virtual;
function vertex(x ,y : double_ptr ) : unsigned; virtual;
procedure normalize(a1 ,a2 : double; ccw : boolean );
end;
{ GLOBAL PROCEDURES }
IMPLEMENTATION
{ LOCAL VARIABLES & CONSTANTS }
{ UNIT IMPLEMENTATION }
{ CONSTRUCT }
constructor arc.Construct;
begin
m_x :=0;
m_y :=0;
m_rx :=0;
m_ry :=0;
m_angle:=0;
m_start:=0;
m_end :=0;
m_da :=0;
m_ccw :=false;
m_path_cmd:=0;
m_scale:=1;
m_initialized:=false;
end;
{ CONSTRUCT }
constructor arc.Construct(x ,y ,rx ,ry ,a1 ,a2 : double; ccw : boolean = true );
begin
Construct;
m_x :=x;
m_y :=y;
m_rx:=rx;
m_ry:=ry;
m_scale:=1;
normalize(a1 ,a2 ,ccw );
end;
{ INIT }
procedure arc.init;
begin
m_x :=x;
m_y :=y;
m_rx:=rx;
m_ry:=ry;
normalize(a1 ,a2 ,ccw );
end;
{ APPROXIMATION_SCALE_ }
procedure arc.approximation_scale_;
begin
m_scale:=s;
if m_initialized then
normalize(m_start ,m_end ,m_ccw );
end;
{ _APPROXIMATION_SCALE }
function arc._approximation_scale;
begin
result:=m_scale;
end;
{ REWIND }
procedure arc.rewind;
begin
m_path_cmd:=path_cmd_move_to;
m_angle :=m_start;
end;
{ VERTEX }
function arc.vertex;
var
pf : unsigned;
begin
if is_stop(m_path_cmd ) then
result:=path_cmd_stop
else
if (m_angle < m_end - m_da / 4 ) <> m_ccw then
begin
x^:=m_x + Cos(m_end ) * m_rx;
y^:=m_y + Sin(m_end ) * m_ry;
m_path_cmd:=path_cmd_stop;
result:=path_cmd_line_to;
end
else
begin
x^:=m_x + Cos(m_angle ) * m_rx;
y^:=m_y + Sin(m_angle ) * m_ry;
m_angle:=m_angle + m_da;
pf :=m_path_cmd;
m_path_cmd:=path_cmd_line_to;
result:=pf;
end;
end;
{ NORMALIZE }
procedure arc.normalize;
var
ra : double;
begin
ra :=(Abs(m_rx ) + Abs(m_ry ) ) / 2;
m_da:=ArcCos(ra / (ra + 0.125 / m_scale ) ) * 2;
if ccw then
while a2 < a1 do
a2:=a2 + (pi * 2.0 )
else
begin
while a1 < a2 do
a1:=a1 + (pi * 2.0 );
m_da:=-m_da;
end;
m_ccw :=ccw;
m_start:=a1;
m_end :=a2;
m_initialized:=true;
end;
END.
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