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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
//
//----------------------------------------------------------------------------
//
// Simple Bresenham interpolator for ellipsees
//
// [Pascal Port History] -----------------------------------------------------
//
// 31.01.2006-Milano: Unit port establishment
//
{ agg_ellipse_bresenham.pas }
unit
agg_ellipse_bresenham ;
INTERFACE
{$I agg_mode.inc }
uses
agg_basics ;
{ TYPES DEFINITION }
type
ellipse_bresenham_interpolator = object
m_rx2 ,
m_ry2 ,
m_two_rx2 ,
m_two_ry2 ,
m_dx ,
m_dy ,
m_inc_x ,
m_inc_y ,
m_cur_f : int;
constructor Construct(rx ,ry : int );
function _dx : int;
function _dy : int;
procedure inc_operator;
end;
{ GLOBAL PROCEDURES }
IMPLEMENTATION
{ LOCAL VARIABLES & CONSTANTS }
{ UNIT IMPLEMENTATION }
{ CONSTRUCT }
constructor ellipse_bresenham_interpolator.Construct;
begin
m_rx2:=rx * rx;
m_ry2:=ry * ry;
m_two_rx2:=m_rx2 shl 1;
m_two_ry2:=m_ry2 shl 1;
m_dx:=0;
m_dy:=0;
m_inc_x:=0;
m_inc_y:=-ry * m_two_rx2;
m_cur_f:=0;
end;
{ _DX }
function ellipse_bresenham_interpolator._dx;
begin
result:=m_dx;
end;
{ _DY }
function ellipse_bresenham_interpolator._dy;
begin
result:=m_dy;
end;
{ INC_OPERATOR }
procedure ellipse_bresenham_interpolator.inc_operator;
var
mx ,my ,mxy ,min_m ,fx ,fy ,fxy : int;
flag : boolean;
begin
mx:=m_cur_f + m_inc_x + m_ry2;
fx:=mx;
if mx < 0 then
mx:=-mx;
my:=m_cur_f + m_inc_y + m_rx2;
fy:=my;
if my < 0 then
my:=-my;
mxy:=m_cur_f + m_inc_x + m_ry2 + m_inc_y + m_rx2;
fxy:=mxy;
if mxy < 0 then
mxy:=-mxy;
min_m:=mx;
flag :=true;
if min_m > my then
begin
min_m:=my;
flag :=false;
end;
m_dx:=0;
m_dy:=0;
if min_m > mxy then
begin
inc(m_inc_x ,m_two_ry2 );
inc(m_inc_y ,m_two_rx2 );
m_cur_f:=fxy;
m_dx:=1;
m_dy:=1;
exit;
end;
if flag then
begin
inc(m_inc_x ,m_two_ry2 );
m_cur_f:=fx;
m_dx :=1;
exit;
end;
inc(m_inc_y ,m_two_rx2 );
m_cur_f:=fy;
m_dy :=1;
end;
END.
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