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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
+//----------------------------------------------------------------------------
+//
+// Liang-Barsky clipping
+//
+//----------------------------------------------------------------------------
+#ifndef AGG_CLIP_LIANG_BARSKY_INCLUDED
+#define AGG_CLIP_LIANG_BARSKY_INCLUDED
+
+#include "agg_basics.h"
+
+namespace agg
+{
+
+ //----------------------------------------------------------clipping_flags
+ // 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
+ //
+ //
+ template<class T>
+ inline unsigned clipping_flags(T x, T y, const rect_base<T>& clip_box)
+ {
+ return (x > clip_box.x2) |
+ ((y > clip_box.y2) << 1) |
+ ((x < clip_box.x1) << 2) |
+ ((y < clip_box.y1) << 3);
+ }
+
+
+
+ //-------------------------------------------------------clip_liang_barsky
+ template<class T>
+ /*inline*/ unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
+ const rect_base<T>& clip_box,
+ T* x, T* y)
+ {
+ const double nearzero = 1e-30;
+
+ double deltax = x2 - x1;
+ double deltay = y2 - y1;
+ double xin;
+ double xout;
+ double yin;
+ double yout;
+ double tinx;
+ double tiny;
+ double toutx;
+ double touty;
+ double tin1;
+ double tin2;
+ double tout1;
+ unsigned np = 0;
+
+ if(deltax == 0.0)
+ {
+ // bump off of the vertical
+ deltax = (x1 > clip_box.x1) ? -nearzero : nearzero;
+ }
+
+ if(deltay == 0.0)
+ {
+ // bump off of the horizontal
+ deltay = (y1 > clip_box.y1) ? -nearzero : nearzero;
+ }
+
+ if(deltax > 0.0)
+ {
+ // points to right
+ xin = clip_box.x1;
+ xout = clip_box.x2;
+ }
+ else
+ {
+ xin = clip_box.x2;
+ xout = clip_box.x1;
+ }
+
+ if(deltay > 0.0)
+ {
+ // points up
+ yin = clip_box.y1;
+ yout = clip_box.y2;
+ }
+ else
+ {
+ yin = clip_box.y2;
+ yout = clip_box.y1;
+ }
+
+ tinx = (xin - x1) / deltax;
+ tiny = (yin - y1) / deltay;
+
+ if (tinx < tiny)
+ {
+ // hits x first
+ tin1 = tinx;
+ tin2 = tiny;
+ }
+ else
+ {
+ // hits y first
+ tin1 = tiny;
+ tin2 = tinx;
+ }
+
+ if(tin1 <= 1.0)
+ {
+ if(0.0 < tin1)
+ {
+ *x++ = (T)xin;
+ *y++ = (T)yin;
+ ++np;
+ }
+
+ if(tin2 <= 1.0)
+ {
+ toutx = (xout - x1) / deltax;
+ touty = (yout - y1) / deltay;
+
+ tout1 = (toutx < touty) ? toutx : touty;
+
+ if(tin2 > 0.0 || tout1 > 0.0)
+ {
+ if(tin2 <= tout1)
+ {
+ if(tin2 > 0.0)
+ {
+ if(tinx > tiny)
+ {
+ *x++ = (T)xin;
+ *y++ = (T)(y1 + tinx * deltay);
+ }
+ else
+ {
+ *x++ = (T)(x1 + tiny * deltax);
+ *y++ = (T)yin;
+ }
+ ++np;
+ }
+
+ if(tout1 < 1.0)
+ {
+ if(toutx < touty)
+ {
+ *x++ = (T)xout;
+ *y++ = (T)(y1 + toutx * deltay);
+ }
+ else
+ {
+ *x++ = (T)(x1 + touty * deltax);
+ *y++ = (T)yout;
+ }
+ }
+ else
+ {
+ *x++ = x2;
+ *y++ = y2;
+ }
+ ++np;
+ }
+ else
+ {
+ if(tinx > tiny)
+ {
+ *x++ = (T)xin;
+ *y++ = (T)yout;
+ }
+ else
+ {
+ *x++ = (T)xout;
+ *y++ = (T)yin;
+ }
+ ++np;
+ }
+ }
+ }
+ }
+ return np;
+ }
+
+
+}
+
+#endif