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106 lines
3.1 KiB
106 lines
3.1 KiB
//---------------------------------------------------------------------------- |
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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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// Arc vertex generator |
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// |
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//---------------------------------------------------------------------------- |
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#include <cmath> |
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#include "agg_arc.h" |
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namespace agg |
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{ |
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//------------------------------------------------------------------------ |
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arc::arc(double x, double y, |
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double rx, double ry, |
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double a1, double a2, |
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bool ccw) : |
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m_x(x), m_y(y), m_rx(rx), m_ry(ry), m_scale(1.0) |
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{ |
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normalize(a1, a2, ccw); |
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} |
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//------------------------------------------------------------------------ |
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void arc::init(double x, double y, |
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double rx, double ry, |
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double a1, double a2, |
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bool ccw) |
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{ |
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m_x = x; m_y = y; |
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m_rx = rx; m_ry = ry; |
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normalize(a1, a2, ccw); |
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} |
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//------------------------------------------------------------------------ |
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void arc::approximation_scale(double s) |
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{ |
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m_scale = s; |
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if(m_initialized) |
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{ |
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normalize(m_start, m_end, m_ccw); |
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} |
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} |
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//------------------------------------------------------------------------ |
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void arc::rewind(unsigned) |
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{ |
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m_path_cmd = path_cmd_move_to; |
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m_angle = m_start; |
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} |
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//------------------------------------------------------------------------ |
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unsigned arc::vertex(double* x, double* y) |
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{ |
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if(is_stop(m_path_cmd)) return path_cmd_stop; |
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if((m_angle < m_end - m_da/4) != m_ccw) |
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{ |
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*x = m_x + std::cos(m_end) * m_rx; |
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*y = m_y + std::sin(m_end) * m_ry; |
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m_path_cmd = path_cmd_stop; |
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return path_cmd_line_to; |
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} |
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*x = m_x + std::cos(m_angle) * m_rx; |
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*y = m_y + std::sin(m_angle) * m_ry; |
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m_angle += m_da; |
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unsigned pf = m_path_cmd; |
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m_path_cmd = path_cmd_line_to; |
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return pf; |
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} |
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//------------------------------------------------------------------------ |
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void arc::normalize(double a1, double a2, bool ccw) |
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{ |
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double ra = (std::fabs(m_rx) + std::fabs(m_ry)) / 2; |
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m_da = std::acos(ra / (ra + 0.125 / m_scale)) * 2; |
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if(ccw) |
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{ |
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while(a2 < a1) a2 += pi * 2.0; |
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} |
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else |
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{ |
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while(a1 < a2) a1 += pi * 2.0; |
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m_da = -m_da; |
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} |
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m_ccw = ccw; |
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m_start = a1; |
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m_end = a2; |
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m_initialized = true; |
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} |
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}
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