Ignition Math

API Reference

6.9.3~pre2
Triangle3.hh
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17 #ifndef IGNITION_MATH_TRIANGLE3_HH_
18 #define IGNITION_MATH_TRIANGLE3_HH_
19 
20 #include <ignition/math/Helpers.hh>
21 #include <ignition/math/Line3.hh>
22 #include <ignition/math/Plane.hh>
23 #include <ignition/math/Vector3.hh>
24 #include <ignition/math/config.hh>
25 
26 namespace ignition
27 {
28  namespace math
29  {
30  // Inline bracket to help doxygen filtering.
31  inline namespace IGNITION_MATH_VERSION_NAMESPACE {
32  //
35  template<typename T>
36  class Triangle3
37  {
39  public: Triangle3() = default;
40 
49  public: Triangle3(const Vector3<T> &_pt1,
50  const Vector3<T> &_pt2,
51  const Vector3<T> &_pt3)
52  {
53  this->Set(_pt1, _pt2, _pt3);
54  }
55 
65  public: void Set(const unsigned int _index, const Vector3<T> &_pt)
66  {
67  this->pts[clamp(_index, 0u, 2u)] = _pt;
68  }
69 
79  public: void Set(const Vector3<T> &_pt1,
80  const Vector3<T> &_pt2,
81  const Vector3<T> &_pt3)
82  {
83  this->pts[0] = _pt1;
84  this->pts[1] = _pt2;
85  this->pts[2] = _pt3;
86  }
87 
92  public: bool Valid() const
93  {
94  T a = this->Side(0).Length();
95  T b = this->Side(1).Length();
96  T c = this->Side(2).Length();
97  return (a+b) > c && (b+c) > a && (c+a) > b;
98  }
99 
107  public: Line3<T> Side(const unsigned int _index) const
108  {
109  if (_index == 0)
110  return Line3<T>(this->pts[0], this->pts[1]);
111  else if (_index == 1)
112  return Line3<T>(this->pts[1], this->pts[2]);
113  else
114  return Line3<T>(this->pts[2], this->pts[0]);
115  }
116 
122  public: bool Contains(const Line3<T> &_line) const
123  {
124  return this->Contains(_line[0]) && this->Contains(_line[1]);
125  }
126 
130  public: bool Contains(const Vector3<T> &_pt) const
131  {
132  // Make sure the point is on the same plane as the triangle
133  if (Planed(this->Normal()).Side(Vector3d(_pt[0], _pt[1], _pt[2]))
134  == Planed::NO_SIDE)
135  {
136  Vector3<T> v0 = this->pts[2] - this->pts[0];
137  Vector3<T> v1 = this->pts[1] - this->pts[0];
138  Vector3<T> v2 = _pt - this->pts[0];
139 
140  double dot00 = v0.Dot(v0);
141  double dot01 = v0.Dot(v1);
142  double dot02 = v0.Dot(v2);
143  double dot11 = v1.Dot(v1);
144  double dot12 = v1.Dot(v2);
145 
146  // Compute barycentric coordinates
147  double invDenom = 1.0 / (dot00 * dot11 - dot01 * dot01);
148  double u = (dot11 * dot02 - dot01 * dot12) * invDenom;
149  double v = (dot00 * dot12 - dot01 * dot02) * invDenom;
150 
151  // Check if point is in triangle
152  return (u >= 0) && (v >= 0) && (u + v <= 1);
153  }
154  return false;
155  }
156 
159  public: Vector3d Normal() const
160  {
161  return math::Vector3d::Normal(
162  Vector3d(this->pts[0][0], this->pts[0][1], this->pts[0][2]),
163  Vector3d(this->pts[1][0], this->pts[1][1], this->pts[1][2]),
164  Vector3d(this->pts[2][0], this->pts[2][1], this->pts[2][2]));
165  }
166 
183  public: bool Intersects(
184  const Line3<T> &_line, Vector3<T> &_ipt1) const
185  {
186  // Triangle normal
187  Vector3d norm = this->Normal();
188 
189  // Ray direction to intersect with triangle
190  Vector3<T> dir = (_line[1] - _line[0]).Normalize();
191 
192  double denom = norm.Dot(Vector3d(dir[0], dir[1], dir[2]));
193 
194  // Handle the case when the line is not co-planar with the triangle
195  if (!math::equal(denom, 0.0))
196  {
197  // Distance from line start to triangle intersection
198  Vector3<T> diff = _line[0] - this->pts[0];
199  double intersection =
200  -norm.Dot(Vector3d(diff[0], diff[1], diff[2])) / denom;
201 
202  // Make sure the ray intersects the triangle
203  if (intersection < 1.0 || intersection > _line.Length())
204  return false;
205 
206  // Return point of intersection
207  _ipt1 = _line[0] + (dir * intersection);
208 
209  return true;
210  }
211  // Line co-planar with triangle
212  else
213  {
214  // If the line is completely inside the triangle
215  if (this->Contains(_line))
216  {
217  _ipt1 = _line[0];
218  return true;
219  }
220  // If the line intersects the first side
221  else if (_line.Intersect(this->Side(0), _ipt1))
222  {
223  return true;
224  }
225  // If the line intersects the second side
226  else if (_line.Intersect(this->Side(1), _ipt1))
227  {
228  return true;
229  }
230  // If the line intersects the third side
231  else if (_line.Intersect(this->Side(2), _ipt1))
232  {
233  return true;
234  }
235  }
236 
237  return false;
238  }
239 
242  public: T Perimeter() const
243  {
244  return this->Side(0).Length() + this->Side(1).Length() +
245  this->Side(2).Length();
246  }
247 
250  public: double Area() const
251  {
252  double s = this->Perimeter() / 2.0;
253  T a = this->Side(0).Length();
254  T b = this->Side(1).Length();
255  T c = this->Side(2).Length();
256 
257  // Heron's formula
258  // http://en.wikipedia.org/wiki/Heron%27s_formula
259  return sqrt(s * (s-a) * (s-b) * (s-c));
260  }
261 
266  public: Vector3<T> operator[](const size_t _index) const
267  {
268  return this->pts[clamp(_index, IGN_ZERO_SIZE_T, IGN_TWO_SIZE_T)];
269  }
270 
272  private: Vector3<T> pts[3];
273  };
274 
277 
280 
283  }
284  }
285 }
286 #endif
Vector3d Normal() const
Get the triangle&#39;s normal vector.
Definition: Triangle3.hh:159
On the plane.
Definition: Plane.hh:54
Triangle3< double > Triangle3d
Double specialization of the Triangle class.
Definition: Triangle3.hh:279
Plane< double > Planed
Definition: Plane.hh:285
static Vector3 Normal(const Vector3< T > &_v1, const Vector3< T > &_v2, const Vector3< T > &_v3)
Get a normal vector to a triangle.
Definition: Vector3.hh:258
bool Intersects(const Line3< T > &_line, Vector3< T > &_ipt1) const
Get whether the given line intersects an edge of this triangle.
Definition: Triangle3.hh:183
double Area() const
Get the area of this triangle.
Definition: Triangle3.hh:250
Line3< T > Side(const unsigned int _index) const
Get a line segment for one side of the triangle.
Definition: Triangle3.hh:107
bool equal(const T &_a, const T &_b, const T &_epsilon=T(1e-6))
check if two values are equal, within a tolerance
Definition: Helpers.hh:556
Triangle3< float > Triangle3f
Float specialization of the Triangle class.
Definition: Triangle3.hh:282
Triangle3< int > Triangle3i
Integer specialization of the Triangle class.
Definition: Triangle3.hh:276
bool Contains(const Line3< T > &_line) const
Check if this triangle completely contains the given line segment.
Definition: Triangle3.hh:122
T Dot(const Vector3< T > &_v) const
Return the dot product of this vector and another vector.
Definition: Vector3.hh:205
static const size_t IGN_ZERO_SIZE_T
size_t type with a value of 0
Definition: Helpers.hh:227
Vector3< T > operator[](const size_t _index) const
Get one of points that define the triangle.
Definition: Triangle3.hh:266
Triangle3(const Vector3< T > &_pt1, const Vector3< T > &_pt2, const Vector3< T > &_pt3)
Constructor.
Definition: Triangle3.hh:49
void Set(const Vector3< T > &_pt1, const Vector3< T > &_pt2, const Vector3< T > &_pt3)
Set all vertices of the triangle.
Definition: Triangle3.hh:79
The Vector3 class represents the generic vector containing 3 elements. Since it&#39;s commonly used to ke...
Definition: Vector3.hh:41
Vector3< double > Vector3d
Definition: Vector3.hh:770
A 3-dimensional triangle and related functions.
Definition: Triangle3.hh:36
T Perimeter() const
Get the length of the triangle&#39;s perimeter.
Definition: Triangle3.hh:242
static const size_t IGN_TWO_SIZE_T
size_t type with a value of 2
Definition: Helpers.hh:233
A three dimensional line segment. The line is defined by a start and end point.
Definition: Line3.hh:35
T Length() const
Get the length of the line.
Definition: Line3.hh:145
Definition: Angle.hh:42
bool Valid() const
Get whether this triangle is valid, based on triangle inequality: the sum of the lengths of any two s...
Definition: Triangle3.hh:92
bool Contains(const Vector3< T > &_pt) const
Get whether this triangle contains the given point.
Definition: Triangle3.hh:130
T clamp(T _v, T _min, T _max)
Simple clamping function.
Definition: Helpers.hh:406
bool Intersect(const Line3< T > &_line, double _epsilon=1e-6) const
Check if this line intersects the given line segment.
Definition: Line3.hh:267
void Set(const unsigned int _index, const Vector3< T > &_pt)
Set one vertex of the triangle.
Definition: Triangle3.hh:65