//---------------------------------------------------------------------------- // Anti-Grain Geometry (AGG) - Version 2.5 // A high quality rendering engine for C++ // Copyright (C) 2002-2006 Maxim Shemanarev // Contact: mcseem@antigrain.com // mcseemagg@yahoo.com // http://antigrain.com // // AGG is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation; either version 2 // of the License, or (at your option) any later version. // // AGG is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with AGG; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, // MA 02110-1301, USA. //---------------------------------------------------------------------------- #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 |