//---------------------------------------------------------------------------- // 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 { 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); } 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 FX_FLOAT nearzero = 1e-30f; FX_FLOAT deltax = (FX_FLOAT)(x2 - x1); FX_FLOAT deltay = (FX_FLOAT)(y2 - y1); unsigned np = 0; if(deltax == 0) { deltax = (x1 > clip_box.x1) ? -nearzero : nearzero; } FX_FLOAT xin, xout; if(deltax > 0) { xin = (FX_FLOAT)clip_box.x1; xout = (FX_FLOAT)clip_box.x2; } else { xin = (FX_FLOAT)clip_box.x2; xout = (FX_FLOAT)clip_box.x1; } FX_FLOAT tinx = (xin - x1) / deltax; if(deltay == 0) { deltay = (y1 > clip_box.y1) ? -nearzero : nearzero; } FX_FLOAT yin, yout; if(deltay > 0) { yin = (FX_FLOAT)clip_box.y1; yout = (FX_FLOAT)clip_box.y2; } else { yin = (FX_FLOAT)clip_box.y2; yout = (FX_FLOAT)clip_box.y1; } FX_FLOAT tiny = (yin - y1) / deltay; FX_FLOAT tin1, tin2; if (tinx < tiny) { tin1 = tinx; tin2 = tiny; } else { tin1 = tiny; tin2 = tinx; } if(tin1 <= 1.0f) { if(0 < tin1) { *x++ = (T)xin; *y++ = (T)yin; ++np; } if(tin2 <= 1.0f) { FX_FLOAT toutx = (xout - x1) / deltax; FX_FLOAT touty = (yout - y1) / deltay; FX_FLOAT tout1 = (toutx < touty) ? toutx : touty; if (tin2 > 0 || tout1 > 0) { if(tin2 <= tout1) { if(tin2 > 0) { if(tinx > tiny) { *x++ = (T)xin; *y++ = (T)(y1 + (deltay * tinx)); } else { *x++ = (T)(x1 + (deltax * tiny)); *y++ = (T)yin; } ++np; } if(tout1 < 1.0f) { if(toutx < touty) { *x++ = (T)xout; *y++ = (T)(y1 + (deltay * toutx)); } else { *x++ = (T)(x1 + (deltax * touty)); *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