source/geometry/halfspace.h

   1 #ifndef MSP_GEOMETRY_HALFSPACE_H_
   2 #define MSP_GEOMETRY_HALFSPACE_H_
   3
   4 #include "shape.h"
   5
   6 namespace Msp {
   7 namespace Geometry {
   8
   9 /**
  10 An infinite shape consisting of the space on one side of a plane.  Mostly
  11 useful when composited with other shapes.
  12 */
  13 template<typename T, unsigned D>
  14 class HalfSpace: public Shape<T, D>
  15 {
  16 private:
  17         LinAl::Vector<T, D> normal;
  18
  19 public:
  20         HalfSpace();
  21         HalfSpace(const LinAl::Vector<T, D> &);
  22
  23         virtual HalfSpace *clone() const;
  24
  25         const LinAl::Vector<T, D> &get_normal() const { return normal; }
  26
  27         virtual BoundingBox<T, D> get_axis_aligned_bounding_box() const;
  28         virtual bool contains(const LinAl::Vector<T, D> &) const;
  29         virtual unsigned get_max_ray_intersections() const { return 1; }
  30         virtual unsigned get_intersections(const Ray<T, D> &, SurfacePoint<T, D> *, unsigned) const;
  31 };
  32
  33 template<typename T, unsigned D>
  34 inline HalfSpace<T, D>::HalfSpace()
  35 {
  36         normal[0] = T(1);
  37 }
  38
  39 template<typename T, unsigned D>
  40 inline HalfSpace<T, D>::HalfSpace(const LinAl::Vector<T, D> &n):
  41         normal(normalize(n))
  42 { }
  43
  44 template<typename T, unsigned D>
  45 inline HalfSpace<T, D> *HalfSpace<T, D>::clone() const
  46 {
  47         return new HalfSpace<T, D>(normal);
  48 }
  49
  50 template<typename T, unsigned D>
  51 inline BoundingBox<T, D> HalfSpace<T, D>::get_axis_aligned_bounding_box() const
  52 {
  53         // XXX If the normal is aligned to an axis, should the bounding box reflect that?
  54         return ~BoundingBox<T, D>();
  55 }
  56
  57 template<typename T, unsigned D>
  58 inline bool HalfSpace<T, D>::contains(const LinAl::Vector<T, D> &point) const
  59 {
  60         return inner_product(point, normal)<=T(0);
  61 }
  62
  63 template<typename T, unsigned D>
  64 inline unsigned HalfSpace<T, D>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
  65 {
  66         T d = inner_product(ray.get_start(), normal);
  67         T c = inner_product(ray.get_direction(), normal);
  68         if(c==T(0))
  69                 return 0;
  70
  71         T x = -d/c;
  72         if(ray.check_limits(x))
  73         {
  74                 if(points && size>0)
  75                 {
  76                         points[0].position = ray.get_start()+ray.get_direction()*x;
  77                         points[0].normal = normal;
  78                         points[0].distance = x;
  79                 }
  80
  81                 return 1;
  82         }
  83
  84         return 0;
  85 }
  86
  87 } // namespace Geometry
  88 } // namespace Msp
  89
  90 #endif