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Diffstat (limited to 'agg/source/agg_vpgen_clip_polygon.cpp')
-rwxr-xr-x | agg/source/agg_vpgen_clip_polygon.cpp | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/agg/source/agg_vpgen_clip_polygon.cpp b/agg/source/agg_vpgen_clip_polygon.cpp new file mode 100755 index 000000000000..e3a0b71d821b --- /dev/null +++ b/agg/source/agg_vpgen_clip_polygon.cpp @@ -0,0 +1,133 @@ +//---------------------------------------------------------------------------- +// 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; + } + + +} |