106 lines
2.8 KiB
C++
106 lines
2.8 KiB
C++
//----------------------------------------------------------------------------
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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 <math.h>
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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 + cos(m_end) * m_rx;
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*y = m_y + 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 + cos(m_angle) * m_rx;
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*y = m_y + 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 = (fabs(m_rx) + fabs(m_ry)) / 2;
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m_da = 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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