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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.3
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//----------------------------------------------------------------------------
#include "agg_vpgen_clip_polygon.h"
#include "agg_clip_liang_barsky.h"
namespace agg
{
//------------------------------------------------------------------------
// Determine the clipping code of the vertex according to the
// Cyrus-Beck line clipping algorithm
//
// | |
// 0110 | 0010 | 0011
// | |
// -------+--------+-------- clip_box.y2
// | |
// 0100 | 0000 | 0001
// | |
// -------+--------+-------- clip_box.y1
// | |
// 1100 | 1000 | 1001
// | |
// clip_box.x1 clip_box.x2
//
//
unsigned vpgen_clip_polygon::clipping_flags(double x, double y)
{
if(x < m_clip_box.x1)
{
if(y > m_clip_box.y2) return 6;
if(y < m_clip_box.y1) return 12;
return 4;
}
if(x > m_clip_box.x2)
{
if(y > m_clip_box.y2) return 3;
if(y < m_clip_box.y1) return 9;
return 1;
}
if(y > m_clip_box.y2) return 2;
if(y < m_clip_box.y1) return 8;
return 0;
}
//----------------------------------------------------------------------------
void vpgen_clip_polygon::reset()
{
m_vertex = 0;
m_num_vertices = 0;
}
//----------------------------------------------------------------------------
void vpgen_clip_polygon::move_to(double x, double y)
{
m_vertex = 0;
m_num_vertices = 0;
m_clip_flags = clipping_flags(x, y);
if(m_clip_flags == 0)
{
m_x[0] = x;
m_y[0] = y;
m_num_vertices = 1;
}
m_x1 = x;
m_y1 = y;
m_cmd = path_cmd_move_to;
}
//----------------------------------------------------------------------------
void vpgen_clip_polygon::line_to(double x, double y)
{
m_vertex = 0;
m_num_vertices = 0;
unsigned flags = clipping_flags(x, y);
if(m_clip_flags == flags)
{
if(flags == 0)
{
m_x[0] = x;
m_y[0] = y;
m_num_vertices = 1;
}
}
else
{
m_num_vertices = clip_liang_barsky(m_x1, m_y1,
x, y,
m_clip_box,
m_x, m_y);
}
m_clip_flags = flags;
m_x1 = x;
m_y1 = y;
}
//----------------------------------------------------------------------------
unsigned vpgen_clip_polygon::vertex(double* x, double* y)
{
if(m_vertex < m_num_vertices)
{
*x = m_x[m_vertex];
*y = m_y[m_vertex];
++m_vertex;
unsigned cmd = m_cmd;
m_cmd = path_cmd_line_to;
return cmd;
}
return path_cmd_stop;
}
}
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