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https://gitlab.com/freepascal.org/lazarus/lazarus.git
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176 lines
2.8 KiB
ObjectPascal
176 lines
2.8 KiB
ObjectPascal
//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4 (Public License)
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Anti-Grain Geometry - Version 2.4 Release Milano 3 (AggPas 2.4 RM3)
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// Pascal Port By: Milan Marusinec alias Milano
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// milan@marusinec.sk
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// http://www.aggpas.org
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// Copyright (c) 2005-2006
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//
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//----------------------------------------------------------------------------
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//
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// Simple Bresenham interpolator for ellipsees
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//
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// [Pascal Port History] -----------------------------------------------------
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//
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// 31.01.2006-Milano: Unit port establishment
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//
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{ agg_ellipse_bresenham.pas }
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unit
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agg_ellipse_bresenham ;
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INTERFACE
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{$I agg_mode.inc }
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uses
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agg_basics ;
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{ TYPES DEFINITION }
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type
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ellipse_bresenham_interpolator = object
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m_rx2 ,
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m_ry2 ,
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m_two_rx2 ,
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m_two_ry2 ,
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m_dx ,
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m_dy ,
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m_inc_x ,
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m_inc_y ,
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m_cur_f : int;
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constructor Construct(rx ,ry : int );
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function _dx : int;
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function _dy : int;
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procedure inc_operator;
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end;
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{ GLOBAL PROCEDURES }
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IMPLEMENTATION
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{ LOCAL VARIABLES & CONSTANTS }
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{ UNIT IMPLEMENTATION }
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{ CONSTRUCT }
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constructor ellipse_bresenham_interpolator.Construct;
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begin
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m_rx2:=rx * rx;
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m_ry2:=ry * ry;
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m_two_rx2:=m_rx2 shl 1;
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m_two_ry2:=m_ry2 shl 1;
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m_dx:=0;
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m_dy:=0;
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m_inc_x:=0;
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m_inc_y:=-ry * m_two_rx2;
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m_cur_f:=0;
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end;
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{ _DX }
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function ellipse_bresenham_interpolator._dx;
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begin
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result:=m_dx;
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end;
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{ _DY }
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function ellipse_bresenham_interpolator._dy;
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begin
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result:=m_dy;
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end;
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{ INC_OPERATOR }
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procedure ellipse_bresenham_interpolator.inc_operator;
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var
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mx ,my ,mxy ,min_m ,fx ,fy ,fxy : int;
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flag : boolean;
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begin
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mx:=m_cur_f + m_inc_x + m_ry2;
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fx:=mx;
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if mx < 0 then
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mx:=-mx;
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my:=m_cur_f + m_inc_y + m_rx2;
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fy:=my;
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if my < 0 then
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my:=-my;
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mxy:=m_cur_f + m_inc_x + m_ry2 + m_inc_y + m_rx2;
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fxy:=mxy;
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if mxy < 0 then
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mxy:=-mxy;
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min_m:=mx;
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flag :=true;
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if min_m > my then
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begin
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min_m:=my;
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flag :=false;
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end;
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m_dx:=0;
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m_dy:=0;
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if min_m > mxy then
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begin
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inc(m_inc_x ,m_two_ry2 );
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inc(m_inc_y ,m_two_rx2 );
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m_cur_f:=fxy;
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m_dx:=1;
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m_dy:=1;
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exit;
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end;
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if flag then
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begin
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inc(m_inc_x ,m_two_ry2 );
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m_cur_f:=fx;
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m_dx :=1;
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exit;
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end;
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inc(m_inc_y ,m_two_rx2 );
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m_cur_f:=fy;
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m_dy :=1;
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end;
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END.
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