source/geometry/halfspace.h

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