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