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