source/geometry/hyperbox.h

   1 #ifndef MSP_GEOMETRY_HYPERBOX_H_
   2 #define MSP_GEOMETRY_HYPERBOX_H_
   3
   4 #include <algorithm>
   5 #include <cmath>
   6 #include <msp/linal/vector.h>
   7 #include "ray.h"
   8 #include "shape.h"
   9 #include "surfacepoint.h"
  10
  11 namespace Msp {
  12 namespace Geometry {
  13
  14 /**
  15 A shape bounded by planar faces at right angles to each other.  Two- and three-
  16 dimensional cases are Rectangle and Box, respectively.
  17 */
  18 template<typename T, unsigned D>
  19 class HyperBox: public Shape<T, D>
  20 {
  21 private:
  22         LinAl::Vector<T, D> dimensions;
  23
  24 public:
  25         HyperBox();
  26         explicit HyperBox(const LinAl::Vector<T, D> &);
  27
  28         virtual HyperBox *clone() const;
  29
  30         const LinAl::Vector<T, D> &get_dimensions() const { return dimensions; }
  31         T get_dimension(unsigned) const;
  32
  33         virtual HyperBox<T, D> get_axis_aligned_bounding_box() const { return *this; }
  34         virtual bool contains(const LinAl::Vector<T, D> &) const;
  35         virtual bool check_intersection(const Ray<T, D> &) const;
  36         virtual unsigned get_max_ray_intersections() const { return 2; }
  37         virtual unsigned get_intersections(const Ray<T, D> &, SurfacePoint<T, D> *, unsigned) const;
  38 };
  39
  40 template<typename T, unsigned D>
  41 inline HyperBox<T, D>::HyperBox()
  42 {
  43         for(unsigned i=0; i<D; ++i)
  44                 dimensions[i] = 1;
  45 }
  46
  47 template<typename T, unsigned D>
  48 inline HyperBox<T, D>::HyperBox(const LinAl::Vector<T, D> &d):
  49         dimensions(d)
  50 { }
  51
  52 template<typename T, unsigned D>
  53 inline HyperBox<T, D> *HyperBox<T, D>::clone() const
  54 {
  55         return new HyperBox<T, D>(dimensions);
  56 }
  57
  58 template<typename T, unsigned D>
  59 inline T HyperBox<T, D>::get_dimension(unsigned i) const
  60 {
  61         return dimensions[i];
  62 }
  63
  64 template<typename T, unsigned D>
  65 inline bool HyperBox<T, D>::contains(const LinAl::Vector<T, D> &point) const
  66 {
  67         for(unsigned i=0; i<D; ++i)
  68                 if(abs(point[i])>dimensions[i]/2)
  69                         return false;
  70         return true;
  71 }
  72
  73 template<typename T, unsigned D>
  74 inline bool HyperBox<T, D>::check_intersection(const Ray<T, D> &ray) const
  75 {
  76         return get_intersections(ray, 0, 1);
  77 }
  78
  79 template<typename T, unsigned D>
  80 inline unsigned HyperBox<T, D>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
  81 {
  82         using std::abs;
  83
  84         LinAl::Vector<T, D> half_dim = dimensions/T(2);
  85         unsigned n = 0;
  86         for(unsigned i=0; i<D; ++i)
  87         {
  88                 if(!ray.get_direction()[i])
  89                         continue;
  90
  91                 for(int j=-1; j<=1; j+=2)
  92                 {
  93                         T x = (T(j)*half_dim[i]-ray.get_start()[i])/ray.get_direction()[i];
  94                         if(x<0)
  95                                 continue;
  96
  97                         LinAl::Vector<T, D> p = ray.get_start()+ray.get_direction()*x;
  98
  99                         bool inside = true;
 100                         for(unsigned k=0; (inside && k<D); ++k)
 101                                 inside = (k==i || abs(p[k])<=half_dim[k]);
 102
 103                         if(inside && n<size)
 104                         {
 105                                 if(points)
 106                                 {
 107                                         points[n].position = p;
 108                                         points[n].normal = LinAl::Vector<T, D>();
 109                                         points[n].normal[i] = j;
 110                                         points[n].distance = x;
 111
 112                                         if(n==1 && x<points[0].distance)
 113                                                 std::swap(points[0], points[1]);
 114                                 }
 115
 116                                 ++n;
 117                                 if(n==size || n==2)
 118                                         return n;
 119                         }
 120                 }
 121         }
 122
 123         return n;
 124 }
 125
 126 } // namespace Geometry
 127 } // namespace Msp
 128
 129 #endif