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Diffstat (limited to 'src/agg/agg_clip_liang_barsky.h')
| -rw-r--r-- | src/agg/agg_clip_liang_barsky.h | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/src/agg/agg_clip_liang_barsky.h b/src/agg/agg_clip_liang_barsky.h new file mode 100644 index 000000000..4b5fedbab --- /dev/null +++ b/src/agg/agg_clip_liang_barsky.h @@ -0,0 +1,333 @@ +//---------------------------------------------------------------------------- +// Anti-Grain Geometry - Version 2.4 +// 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 +{ + + //------------------------------------------------------------------------ + enum clipping_flags_e + { + clipping_flags_x1_clipped = 4, + clipping_flags_x2_clipped = 1, + clipping_flags_y1_clipped = 8, + clipping_flags_y2_clipped = 2, + clipping_flags_x_clipped = clipping_flags_x1_clipped | clipping_flags_x2_clipped, + clipping_flags_y_clipped = clipping_flags_y1_clipped | clipping_flags_y2_clipped + }; + + //----------------------------------------------------------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); + } + + //--------------------------------------------------------clipping_flags_x + template<class T> + inline unsigned clipping_flags_x(T x, const rect_base<T>& clip_box) + { + return (x > clip_box.x2) | ((x < clip_box.x1) << 2); + } + + + //--------------------------------------------------------clipping_flags_y + template<class T> + inline unsigned clipping_flags_y(T y, const rect_base<T>& clip_box) + { + return ((y > clip_box.y2) << 1) | ((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; + } + + + //---------------------------------------------------------------------------- + template<class T> + bool clip_move_point(T x1, T y1, T x2, T y2, + const rect_base<T>& clip_box, + T* x, T* y, unsigned flags) + { + T bound; + + if(flags & clipping_flags_x_clipped) + { + if(x1 == x2) + { + return false; + } + bound = (flags & clipping_flags_x1_clipped) ? clip_box.x1 : clip_box.x2; + *y = (T)(double(bound - x1) * (y2 - y1) / (x2 - x1) + y1); + *x = bound; + } + + flags = clipping_flags_y(*y, clip_box); + if(flags & clipping_flags_y_clipped) + { + if(y1 == y2) + { + return false; + } + bound = (flags & clipping_flags_y1_clipped) ? clip_box.y1 : clip_box.y2; + *x = (T)(double(bound - y1) * (x2 - x1) / (y2 - y1) + x1); + *y = bound; + } + return true; + } + + //-------------------------------------------------------clip_line_segment + // Returns: ret >= 4 - Fully clipped + // (ret & 1) != 0 - First point has been moved + // (ret & 2) != 0 - Second point has been moved + // + template<class T> + unsigned clip_line_segment(T* x1, T* y1, T* x2, T* y2, + const rect_base<T>& clip_box) + { + unsigned f1 = clipping_flags(*x1, *y1, clip_box); + unsigned f2 = clipping_flags(*x2, *y2, clip_box); + unsigned ret = 0; + + if((f2 | f1) == 0) + { + // Fully visible + return 0; + } + + if((f1 & clipping_flags_x_clipped) != 0 && + (f1 & clipping_flags_x_clipped) == (f2 & clipping_flags_x_clipped)) + { + // Fully clipped + return 4; + } + + if((f1 & clipping_flags_y_clipped) != 0 && + (f1 & clipping_flags_y_clipped) == (f2 & clipping_flags_y_clipped)) + { + // Fully clipped + return 4; + } + + T tx1 = *x1; + T ty1 = *y1; + T tx2 = *x2; + T ty2 = *y2; + if(f1) + { + if(!clip_move_point(tx1, ty1, tx2, ty2, clip_box, x1, y1, f1)) + { + return 4; + } + if(*x1 == *x2 && *y1 == *y2) + { + return 4; + } + ret |= 1; + } + if(f2) + { + if(!clip_move_point(tx1, ty1, tx2, ty2, clip_box, x2, y2, f2)) + { + return 4; + } + if(*x1 == *x2 && *y1 == *y2) + { + return 4; + } + ret |= 2; + } + return ret; + } + + +} + + +#endif |