1//---------------------------------------------------------------------------- 2// Anti-Grain Geometry - Version 2.4 3// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com) 4// 5// Permission to copy, use, modify, sell and distribute this software 6// is granted provided this copyright notice appears in all copies. 7// This software is provided "as is" without express or implied 8// warranty, and with no claim as to its suitability for any purpose. 9// 10//---------------------------------------------------------------------------- 11// Contact: mcseem@antigrain.com 12// mcseemagg@yahoo.com 13// http://www.antigrain.com 14//---------------------------------------------------------------------------- 15// 16// Arc vertex generator 17// 18//---------------------------------------------------------------------------- 19 20#include <math.h> 21#include "agg_arc.h" 22 23 24namespace agg 25{ 26 //------------------------------------------------------------------------ 27 arc::arc(double x, double y, 28 double rx, double ry, 29 double a1, double a2, 30 bool ccw) : 31 m_x(x), m_y(y), m_rx(rx), m_ry(ry), m_scale(1.0) 32 { 33 normalize(a1, a2, ccw); 34 } 35 36 //------------------------------------------------------------------------ 37 void arc::init(double x, double y, 38 double rx, double ry, 39 double a1, double a2, 40 bool ccw) 41 { 42 m_x = x; m_y = y; 43 m_rx = rx; m_ry = ry; 44 normalize(a1, a2, ccw); 45 } 46 47 //------------------------------------------------------------------------ 48 void arc::approximation_scale(double s) 49 { 50 m_scale = s; 51 if(m_initialized) 52 { 53 normalize(m_start, m_end, m_ccw); 54 } 55 } 56 57 //------------------------------------------------------------------------ 58 void arc::rewind(unsigned) 59 { 60 m_path_cmd = path_cmd_move_to; 61 m_angle = m_start; 62 } 63 64 //------------------------------------------------------------------------ 65 unsigned arc::vertex(double* x, double* y) 66 { 67 if(is_stop(m_path_cmd)) return path_cmd_stop; 68 if((m_angle < m_end - m_da/4) != m_ccw) 69 { 70 *x = m_x + cos(m_end) * m_rx; 71 *y = m_y + sin(m_end) * m_ry; 72 m_path_cmd = path_cmd_stop; 73 return path_cmd_line_to; 74 } 75 76 *x = m_x + cos(m_angle) * m_rx; 77 *y = m_y + sin(m_angle) * m_ry; 78 79 m_angle += m_da; 80 81 unsigned pf = m_path_cmd; 82 m_path_cmd = path_cmd_line_to; 83 return pf; 84 } 85 86 //------------------------------------------------------------------------ 87 void arc::normalize(double a1, double a2, bool ccw) 88 { 89 double ra = (fabs(m_rx) + fabs(m_ry)) / 2; 90 m_da = acos(ra / (ra + 0.125 / m_scale)) * 2; 91 if(ccw) 92 { 93 while(a2 < a1) a2 += pi * 2.0; 94 } 95 else 96 { 97 while(a1 < a2) a1 += pi * 2.0; 98 m_da = -m_da; 99 } 100 m_ccw = ccw; 101 m_start = a1; 102 m_end = a2; 103 m_initialized = true; 104 } 105 106} 107