vmmlib  1.7.0
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intersection.hpp
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32 
33 /* @author Jafet Villafranca
34  *
35  * Implements ray-object intersection, storing the ray parameters as attributes
36  * and implementing intersection tests against different types of objects
37  * (e.g. sphere)
38  */
39 
40 #ifndef __VMML__INTERSECTION__HPP__
41 #define __VMML__INTERSECTION__HPP__
42 
43 #include <vmmlib/vector.hpp>
44 
45 namespace vmml
46 {
47 template< typename T > class intersection
48 {
49 public:
50  typedef vector< 3, T > vec3;
51  typedef vector< 4, T > vec4;
52 
59  intersection( const vec3& origin, const vec3& direction )
60  : _origin ( origin )
61  , _direction ( vmml::normalize( direction ))
62  {}
63  ~intersection() {}
64 
75  bool test_sphere( const vec4& sphere, T& t ) const;
76 
77 private:
78  const vec3 _origin;
79  const vec3 _direction;
80 
81 }; // class intersection
82 
83 
84 template< typename T >
85 bool
86 intersection< T >::test_sphere( const vec4& sphere, T& t ) const
87 {
88  const vec3 center = vec3(sphere.x(), sphere.y(), sphere.z());
89  const T radius = sphere.w();
90 
91  const vec3 centerVec = center - _origin;
92  const T vecProjection = centerVec.dot(_direction);
93 
94  const T sqDistance = centerVec.squared_length();
95  const T sqRadius = radius * radius;
96 
98  if( vecProjection < 0 && sqDistance > sqRadius )
99  return false;
100 
102  const T sqCenterToProj = sqDistance - vecProjection * vecProjection;
103 
104  if( sqCenterToProj > sqRadius )
105  return false;
106 
108  const T distSurface = sqrt( sqRadius - sqCenterToProj );
109 
110  if(sqDistance > sqRadius)
111  t = vecProjection - distSurface;
112  else
113  t = vecProjection + distSurface;
114 
115  return true;
116 }
117 
118 
119 } // namespace vmml
120 
121 #endif
intersection(const vec3 &origin, const vec3 &direction)
Constructors.
bool test_sphere(const vec4 &sphere, T &t) const
Ray Sphere Intersection - Optimized solution "Real-time Rendering 3rd Edition".