Box.cxx

   1 #include "Box.hxx"
   2 #include "InfinitePlane.hxx"
   3
   4 Box::Box() : m_min(Infinity, Infinity, Infinity),
   5   m_max(-Infinity, -Infinity, -Infinity)
   6 {
   7 }
   8
   9 Box::Box(Vec3f min, Vec3f max) : m_min(min), m_max(max)
  10 {
  11 }
  12
  13 Box::~Box()
  14 {
  15 }
  16
  17 Box::Box(const Box& b)
  18 {
  19   m_min = b.m_min;
  20   m_max = b.m_max;
  21 }
  22
  23 Box&
  24 Box::operator=(const Box& b)
  25 {
  26   m_min = b.m_min;
  27   m_max = b.m_max;
  28   return *this;
  29 }
  30
  31 void
  32 Box::Clear()
  33 {
  34 }
  35
  36 void
  37 Box::Extend(const Vec3f& a)
  38 {
  39   // for all three coordinates, move m_max or m_min to the point
  40   for(size_t i = 0; i < 3; i++) {
  41     if(a[i] > m_max[i]) {
  42       m_max[i] = a[i];
  43     } else if(a[i] < m_min[i]) {
  44       m_min[i] = a[i];
  45     } // else: do nothing, coordinate is inside the box
  46   }
  47 }
  48
  49 void
  50 Box::Extend(const Box& box)
  51 {
  52 }
  53
  54 bool
  55 Box::Overlaps(const Box& b) const
  56 {
  57   return false;
  58 }
  59
  60 void
  61 Box::Clip(const Ray& ray, float& tnear, float& tfar) const
  62 {
  63   // Note: equations here are the same as in InfinitePlane::Intersect()
  64   // t = ((o-a)*n) / (d*n)
  65   // o = ray.origin(), d = ray.direction(),
  66   // n = surface normal of plane, a = anchor point of plane
  67   Vec3f diff_min = m_min - ray.origin(); // o-a
  68   Vec3f diff_max = m_max - ray.origin();
  69
  70   float cos_theta;
  71   float tx_near, tx_far;
  72
  73   // clip along x axis
  74   if(cos_theta = ray.direction().dot(Vec3f(1,0,0)) != 0) // if not parallel...
  75     tx_near = diff_min.dot(Vec3f(1,0,0)) / cos_theta;
  76   if(cos_theta = ray.direction().dot(Vec3f(1,0,0)) != 0)
  77     tx_far = diff_max.dot(Vec3f(1,0,0)) / cos_theta;
  78
  79   // clip along y axis
  80   if(cos_theta = ray.direction().dot(Vec3f(0,1,0)) != 0)
  81     ty_near = diff_min.dot(Vec3f(0,1,0)) / cos_theta;
  82   if(cos_theta = ray.direction().dot(Vec3f(0,0,1)) != 0)
  83     ty_far = diff_max.dot(Vec3f(0,1,0)) / cos_theta;
  84
  85   // ray intersects box iff it intersects projection on xy plane
  86   // in this case: tx_near <= ty_near <= tx_far  <= ty_far
  87   //           or: tx_far  <= ty_near <= tx_near <= ty_far
  88   //           or: tx_far  <= ty_far  <= tx_near <= ty_near
  89   //           or: tx_near <= ty_far  <= tx_far  <= ty_near
  90   if(tx_near <= ty_near && tx_far <= ty_near &&
  91     tx_near <= ty_far && tx_far <= ty_far) {
  92
  93     // clip along z axis
  94     if (cos_theta = ray.direction().dot(Vec3f(0, 1, 0)) != 0)
  95       tz_near = diff_min.dot(Vec3f(0, 1, 0)) / cos_theta;
  96     if (cos_theta = ray.direction().dot(Vec3f(0, 0, 1)) != 0)
  97       tz_far = diff_max.dot(Vec3f(0, 1, 0)) / cos_theta;
  98
  99   } else {
 100
 101   }
 102
 103   //////////////////////////
 104
 105 }
 106
 107 const Vec3f&
 108 Box::min() const
 109 {
 110   return m_min;
 111 }
 112
 113 const Vec3f&
 114 Box::max() const
 115 {
 116   return m_max;
 117 }