134 lines
3.7 KiB
C++
134 lines
3.7 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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#include "agg_vpgen_clip_polygon.h"
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#include "agg_clip_liang_barsky.h"
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namespace agg
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{
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//------------------------------------------------------------------------
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// Determine the clipping code of the vertex according to the
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// Cyrus-Beck line clipping algorithm
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//
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// | |
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// 0110 | 0010 | 0011
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// | |
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// -------+--------+-------- clip_box.y2
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// | |
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// 0100 | 0000 | 0001
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// | |
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// -------+--------+-------- clip_box.y1
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// | |
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// 1100 | 1000 | 1001
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// | |
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// clip_box.x1 clip_box.x2
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//
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//
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unsigned vpgen_clip_polygon::clipping_flags(double x, double y)
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{
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if(x < m_clip_box.x1)
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{
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if(y > m_clip_box.y2) return 6;
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if(y < m_clip_box.y1) return 12;
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return 4;
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}
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if(x > m_clip_box.x2)
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{
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if(y > m_clip_box.y2) return 3;
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if(y < m_clip_box.y1) return 9;
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return 1;
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}
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if(y > m_clip_box.y2) return 2;
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if(y < m_clip_box.y1) return 8;
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return 0;
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}
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//----------------------------------------------------------------------------
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void vpgen_clip_polygon::reset()
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{
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m_vertex = 0;
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m_num_vertices = 0;
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}
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//----------------------------------------------------------------------------
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void vpgen_clip_polygon::move_to(double x, double y)
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{
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m_vertex = 0;
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m_num_vertices = 0;
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m_clip_flags = clipping_flags(x, y);
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if(m_clip_flags == 0)
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{
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m_x[0] = x;
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m_y[0] = y;
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m_num_vertices = 1;
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}
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m_x1 = x;
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m_y1 = y;
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m_cmd = path_cmd_move_to;
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}
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//----------------------------------------------------------------------------
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void vpgen_clip_polygon::line_to(double x, double y)
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{
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m_vertex = 0;
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m_num_vertices = 0;
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unsigned flags = clipping_flags(x, y);
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if(m_clip_flags == flags)
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{
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if(flags == 0)
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{
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m_x[0] = x;
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m_y[0] = y;
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m_num_vertices = 1;
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}
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}
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else
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{
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m_num_vertices = clip_liang_barsky(m_x1, m_y1,
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x, y,
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m_clip_box,
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m_x, m_y);
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}
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m_clip_flags = flags;
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m_x1 = x;
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m_y1 = y;
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}
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//----------------------------------------------------------------------------
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unsigned vpgen_clip_polygon::vertex(double* x, double* y)
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{
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if(m_vertex < m_num_vertices)
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{
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*x = m_x[m_vertex];
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*y = m_y[m_vertex];
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++m_vertex;
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unsigned cmd = m_cmd;
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m_cmd = path_cmd_line_to;
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return cmd;
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}
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return path_cmd_stop;
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}
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}
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