doc/html/line2d_8h_source.html

00001 // Copyright (C) 2002-2012 Nikolaus Gebhardt
-00002 // This file is part of the "Irrlicht Engine".
-00003 // For conditions of distribution and use, see copyright notice in irrlicht.h
-00004
-00005 #ifndef __IRR_LINE_2D_H_INCLUDED__
-00006 #define __IRR_LINE_2D_H_INCLUDED__
-00007
-00008 #include "irrTypes.h"
-00009 #include "vector2d.h"
-00010
-00011 namespace irr
-00012 {
-00013 namespace core
-00014 {
-00015
-00017 template <class T>
-00018 class line2d
-00019 {
-00020     public:
-00022         line2d() : start(0,0), end(1,1) {}
-00024         line2d(T xa, T ya, T xb, T yb) : start(xa, ya), end(xb, yb) {}
-00026         line2d(const vector2d<T>& start, const vector2d<T>& end) : start(start), end(end) {}
-00028         line2d(const line2d<T>& other) : start(other.start), end(other.end) {}
-00029
-00030         // operators
-00031
-00032         line2d<T> operator+(const vector2d<T>& point) const { return line2d<T>(start + point, end + point); }
-00033         line2d<T>& operator+=(const vector2d<T>& point) { start += point; end += point; return *this; }
-00034
-00035         line2d<T> operator-(const vector2d<T>& point) const { return line2d<T>(start - point, end - point); }
-00036         line2d<T>& operator-=(const vector2d<T>& point) { start -= point; end -= point; return *this; }
-00037
-00038         bool operator==(const line2d<T>& other) const
-00039         { return (start==other.start && end==other.end) || (end==other.start && start==other.end);}
-00040         bool operator!=(const line2d<T>& other) const
-00041         { return !(start==other.start && end==other.end) || (end==other.start && start==other.end);}
-00042
-00043         // functions
-00045         void setLine(const T& xa, const T& ya, const T& xb, const T& yb){start.set(xa, ya); end.set(xb, yb);}
-00047         void setLine(const vector2d<T>& nstart, const vector2d<T>& nend){start.set(nstart); end.set(nend);}
-00049         void setLine(const line2d<T>& line){start.set(line.start); end.set(line.end);}
-00050
-00052
-00053         T getLength() const { return start.getDistanceFrom(end); }
-00054
-00056
-00057         T getLengthSQ() const { return start.getDistanceFromSQ(end); }
-00058
-00060
-00061         vector2d<T> getMiddle() const
-00062         {
-00063             return (start + end)/(T)2;
-00064         }
-00065
-00067
-00068         vector2d<T> getVector() const { return vector2d<T>(end.X - start.X, end.Y - start.Y); }
-00069
-00071
-00077         bool intersectWith(const line2d<T>& l, vector2d<T>& out, bool checkOnlySegments=true) const
-00078         {
-00079             // Uses the method given at:
-00080             // http://local.wasp.uwa.edu.au/~pbourke/geometry/lineline2d/
-00081             const f32 commonDenominator = (f32)(l.end.Y - l.start.Y)*(end.X - start.X) -
-00082                                             (l.end.X - l.start.X)*(end.Y - start.Y);
-00083
-00084             const f32 numeratorA = (f32)(l.end.X - l.start.X)*(start.Y - l.start.Y) -
-00085                                             (l.end.Y - l.start.Y)*(start.X -l.start.X);
-00086
-00087             const f32 numeratorB = (f32)(end.X - start.X)*(start.Y - l.start.Y) -
-00088                                             (end.Y - start.Y)*(start.X -l.start.X);
-00089
-00090             if(equals(commonDenominator, 0.f))
-00091             {
-00092                 // The lines are either coincident or parallel
-00093                 // if both numerators are 0, the lines are coincident
-00094                 if(equals(numeratorA, 0.f) && equals(numeratorB, 0.f))
-00095                 {
-00096                     // Try and find a common endpoint
-00097                     if(l.start == start || l.end == start)
-00098                         out = start;
-00099                     else if(l.end == end || l.start == end)
-00100                         out = end;
-00101                     // now check if the two segments are disjunct
-00102                     else if (l.start.X>start.X && l.end.X>start.X && l.start.X>end.X && l.end.X>end.X)
-00103                         return false;
-00104                     else if (l.start.Y>start.Y && l.end.Y>start.Y && l.start.Y>end.Y && l.end.Y>end.Y)
-00105                         return false;
-00106                     else if (l.start.X<start.X && l.end.X<start.X && l.start.X<end.X && l.end.X<end.X)
-00107                         return false;
-00108                     else if (l.start.Y<start.Y && l.end.Y<start.Y && l.start.Y<end.Y && l.end.Y<end.Y)
-00109                         return false;
-00110                     // else the lines are overlapping to some extent
-00111                     else
-00112                     {
-00113                         // find the points which are not contributing to the
-00114                         // common part
-00115                         vector2d<T> maxp;
-00116                         vector2d<T> minp;
-00117                         if ((start.X>l.start.X && start.X>l.end.X && start.X>end.X) || (start.Y>l.start.Y && start.Y>l.end.Y && start.Y>end.Y))
-00118                             maxp=start;
-00119                         else if ((end.X>l.start.X && end.X>l.end.X && end.X>start.X) || (end.Y>l.start.Y && end.Y>l.end.Y && end.Y>start.Y))
-00120                             maxp=end;
-00121                         else if ((l.start.X>start.X && l.start.X>l.end.X && l.start.X>end.X) || (l.start.Y>start.Y && l.start.Y>l.end.Y && l.start.Y>end.Y))
-00122                             maxp=l.start;
-00123                         else
-00124                             maxp=l.end;
-00125                         if (maxp != start && ((start.X<l.start.X && start.X<l.end.X && start.X<end.X) || (start.Y<l.start.Y && start.Y<l.end.Y && start.Y<end.Y)))
-00126                             minp=start;
-00127                         else if (maxp != end && ((end.X<l.start.X && end.X<l.end.X && end.X<start.X) || (end.Y<l.start.Y && end.Y<l.end.Y && end.Y<start.Y)))
-00128                             minp=end;
-00129                         else if (maxp != l.start && ((l.start.X<start.X && l.start.X<l.end.X && l.start.X<end.X) || (l.start.Y<start.Y && l.start.Y<l.end.Y && l.start.Y<end.Y)))
-00130                             minp=l.start;
-00131                         else
-00132                             minp=l.end;
-00133
-00134                         // one line is contained in the other. Pick the center
-00135                         // of the remaining points, which overlap for sure
-00136                         out = core::vector2d<T>();
-00137                         if (start != maxp && start != minp)
-00138                             out += start;
-00139                         if (end != maxp && end != minp)
-00140                             out += end;
-00141                         if (l.start != maxp && l.start != minp)
-00142                             out += l.start;
-00143                         if (l.end != maxp && l.end != minp)
-00144                             out += l.end;
-00145                         out.X = (T)(out.X/2);
-00146                         out.Y = (T)(out.Y/2);
-00147                     }
-00148
-00149                     return true; // coincident
-00150                 }
-00151
-00152                 return false; // parallel
-00153             }
-00154
-00155             // Get the point of intersection on this line, checking that
-00156             // it is within the line segment.
-00157             const f32 uA = numeratorA / commonDenominator;
-00158             if(checkOnlySegments && (uA < 0.f || uA > 1.f) )
-00159                 return false; // Outside the line segment
-00160
-00161             const f32 uB = numeratorB / commonDenominator;
-00162             if(checkOnlySegments && (uB < 0.f || uB > 1.f))
-00163                 return false; // Outside the line segment
-00164
-00165             // Calculate the intersection point.
-00166             out.X = (T)(start.X + uA * (end.X - start.X));
-00167             out.Y = (T)(start.Y + uA * (end.Y - start.Y));
-00168             return true;
-00169         }
-00170
-00172
-00173         vector2d<T> getUnitVector() const
-00174         {
-00175             T len = (T)(1.0 / getLength());
-00176             return vector2d<T>((end.X - start.X) * len, (end.Y - start.Y) * len);
-00177         }
-00178
-00180
-00182         f64 getAngleWith(const line2d<T>& l) const
-00183         {
-00184             vector2d<T> vect = getVector();
-00185             vector2d<T> vect2 = l.getVector();
-00186             return vect.getAngleWith(vect2);
-00187         }
-00188
-00190
-00192         T getPointOrientation(const vector2d<T>& point) const
-00193         {
-00194             return ( (end.X - start.X) * (point.Y - start.Y) -
-00195                     (point.X - start.X) * (end.Y - start.Y) );
-00196         }
-00197
-00199
-00200         bool isPointOnLine(const vector2d<T>& point) const
-00201         {
-00202             T d = getPointOrientation(point);
-00203             return (d == 0 && point.isBetweenPoints(start, end));
-00204         }
-00205
-00207
-00208         bool isPointBetweenStartAndEnd(const vector2d<T>& point) const
-00209         {
-00210             return point.isBetweenPoints(start, end);
-00211         }
-00212
-00214
-00216         vector2d<T> getClosestPoint(const vector2d<T>& point, bool checkOnlySegments=true) const
-00217         {
-00218             vector2d<f64> c((f64)(point.X-start.X), (f64)(point.Y- start.Y));
-00219             vector2d<f64> v((f64)(end.X-start.X), (f64)(end.Y-start.Y));
-00220             f64 d = v.getLength();
-00221             if ( d == 0 )   // can't tell much when the line is just a single point
-00222                 return start;
-00223             v /= d;
-00224             f64 t = v.dotProduct(c);
-00225
-00226             if ( checkOnlySegments )
-00227             {
-00228                 if (t < 0) return vector2d<T>((T)start.X, (T)start.Y);
-00229                 if (t > d) return vector2d<T>((T)end.X, (T)end.Y);
-00230             }
-00231
-00232             v *= t;
-00233             return vector2d<T>((T)(start.X + v.X), (T)(start.Y + v.Y));
-00234         }
-00235
-00237         vector2d<T> start;
-00239         vector2d<T> end;
-00240 };
-00241
-00242     // partial specialization to optimize <f32> lines (avoiding casts)
-00243     template <>
-00244     inline vector2df line2d<irr::f32>::getClosestPoint(const vector2df& point, bool checkOnlySegments) const
-00245     {
-00246         vector2df c = point - start;
-00247         vector2df v = end - start;
-00248         f32 d = (f32)v.getLength();
-00249         if ( d == 0 )   // can't tell much when the line is just a single point
-00250             return start;
-00251         v /= d;
-00252         f32 t = v.dotProduct(c);
-00253
-00254         if ( checkOnlySegments )
-00255         {
-00256             if (t < 0) return start;
-00257             if (t > d) return end;
-00258         }
-00259
-00260         v *= t;
-00261         return start + v;
-00262     }
-00263
-00264
-00266     typedef line2d<f32> line2df;
-00268     typedef line2d<s32> line2di;
-00269
-00270 } // end namespace core
-00271 } // end namespace irr
-00272
-00273 #endif
-00274
-