| //---------------------------------------------------------------------------- | |
| // 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 | |
| // | |
| //---------------------------------------------------------------------------- | |
| 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; | |
| }; | |
| } | |