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Diffstat (limited to 'agg/inc/agg_clip_liang_barsky.h')
-rwxr-xr-x | agg/inc/agg_clip_liang_barsky.h | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/agg/inc/agg_clip_liang_barsky.h b/agg/inc/agg_clip_liang_barsky.h new file mode 100755 index 000000000000..e229d52bc6e9 --- /dev/null +++ b/agg/inc/agg_clip_liang_barsky.h @@ -0,0 +1,209 @@ +//---------------------------------------------------------------------------- +// 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 |