113 lines
2.8 KiB
C++
113 lines
2.8 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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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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// Simple Bresenham interpolator for ellipsees
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//
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//----------------------------------------------------------------------------
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#ifndef AGG_ELLIPSE_BRESENHAM_INCLUDED
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#define AGG_ELLIPSE_BRESENHAM_INCLUDED
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#include "agg_basics.h"
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namespace agg
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{
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//------------------------------------------ellipse_bresenham_interpolator
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class ellipse_bresenham_interpolator
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{
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public:
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ellipse_bresenham_interpolator(int rx, int ry) :
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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 << 1),
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m_two_ry2(m_ry2 << 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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{}
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int dx() const { return m_dx; }
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int dy() const { return m_dy; }
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void operator++ ()
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{
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int mx, my, mxy, min_m;
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int fx, fy, fxy;
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mx = fx = m_cur_f + m_inc_x + m_ry2;
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if(mx < 0) mx = -mx;
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my = fy = m_cur_f + m_inc_y + m_rx2;
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if(my < 0) my = -my;
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mxy = fxy = m_cur_f + m_inc_x + m_ry2 + m_inc_y + m_rx2;
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if(mxy < 0) mxy = -mxy;
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min_m = mx;
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bool flag = true;
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if(min_m > my)
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{
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min_m = my;
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flag = false;
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}
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m_dx = m_dy = 0;
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if(min_m > mxy)
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{
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m_inc_x += m_two_ry2;
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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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return;
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}
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if(flag)
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{
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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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return;
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}
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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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}
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private:
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int m_rx2;
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int m_ry2;
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int m_two_rx2;
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int m_two_ry2;
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int m_dx;
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int m_dy;
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int m_inc_x;
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int m_inc_y;
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int m_cur_f;
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};
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}
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#endif
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