source/geometry/transformedshape.h

   1 #ifndef MSP_GEOMETRY_TRANSFORMEDSHAPE_H_
   2 #define MSP_GEOMETRY_TRANSFORMEDSHAPE_H_
   3
   4 #include "affinetransformation.h"
   5 #include "shape.h"
   6
   7 namespace Msp {
   8 namespace Geometry {
   9
  10 /**
  11 A shape modified by an affine transformation.
  12 */
  13 template<typename T, unsigned D>
  14 class TransformedShape: public Shape<T, D>
  15 {
  16 private:
  17         Shape<T, D> *shape;
  18         AffineTransformation<T, D> transformation;
  19         AffineTransformation<T, D> inverse_trans;
  20
  21 public:
  22         TransformedShape(const Shape<T, D> &, const AffineTransformation<T, D> &);
  23         TransformedShape(const TransformedShape &);
  24         TransformedShape &operator=(const TransformedShape &);
  25         ~TransformedShape();
  26
  27         virtual TransformedShape *clone() const;
  28
  29         const Shape<T, D> &get_shape() const { return *shape; }
  30         const AffineTransformation<T, D> &get_transformation() const { return transformation; }
  31
  32         virtual BoundingBox<T, D> get_axis_aligned_bounding_box() const;
  33         virtual bool contains(const LinAl::Vector<T, D> &) const;
  34 private:
  35         Ray<T, D> make_local_ray(const Ray<T, D> &) const;
  36 public:
  37         virtual unsigned get_max_ray_intersections() const { return shape->get_max_ray_intersections(); }
  38         virtual unsigned get_intersections(const Ray<T, D> &, SurfacePoint<T, D> *, unsigned) const;
  39 };
  40
  41 template<typename T, unsigned D>
  42 inline TransformedShape<T, D>::TransformedShape(const Shape<T, D> &s, const AffineTransformation<T, D> &t):
  43         shape(s.clone()),
  44         transformation(t),
  45         inverse_trans(invert(t))
  46 { }
  47
  48 template<typename T, unsigned D>
  49 inline TransformedShape<T, D>::TransformedShape(const TransformedShape<T, D> &other):
  50         shape(other.shape->clone()),
  51         transformation(other.transformation),
  52         inverse_trans(other.inverse_trans)
  53 { }
  54
  55 template<typename T, unsigned D>
  56 inline TransformedShape<T, D> &TransformedShape<T, D>::operator=(const TransformedShape<T, D> &other)
  57 {
  58         delete shape;
  59         shape = other.shape->clone();
  60         transformation = other.transformation;
  61         inverse_trans = other.inverse_trans;
  62 }
  63
  64 template<typename T, unsigned D>
  65 inline TransformedShape<T, D>::~TransformedShape()
  66 {
  67         delete shape;
  68 }
  69
  70 template<typename T, unsigned D>
  71 inline TransformedShape<T, D> *TransformedShape<T, D>::clone() const
  72 {
  73         return new TransformedShape<T, D>(*this);
  74 }
  75
  76 template<typename T, unsigned D>
  77 inline BoundingBox<T, D> TransformedShape<T, D>::get_axis_aligned_bounding_box() const
  78 {
  79         BoundingBox<T, D> inner_bbox = shape->get_axis_aligned_bounding_box();
  80
  81         LinAl::Vector<T, D> min_pt;
  82         LinAl::Vector<T, D> max_pt;
  83         for(unsigned i=0; i<(1<<D); ++i)
  84         {
  85                 LinAl::Vector<T, D> point;
  86                 for(unsigned j=0; j<D; ++j)
  87                         point[j] = ((i>>j)&1 ? inner_bbox.get_maximum_coordinate(j) : inner_bbox.get_minimum_coordinate(j));
  88
  89                 point = transformation.transform(point);
  90
  91                 if(i==0)
  92                 {
  93                         min_pt = point;
  94                         max_pt = point;
  95                 }
  96                 else
  97                 {
  98                         for(unsigned j=0; j<D; ++j)
  99                         {
 100                                 min_pt[j] = std::min(min_pt[j], point[j]);
 101                                 max_pt[j] = std::max(max_pt[j], point[j]);
 102                         }
 103                 }
 104         }
 105
 106         return BoundingBox<T, D>(min_pt, max_pt);
 107 }
 108
 109 template<typename T, unsigned D>
 110 inline bool TransformedShape<T, D>::contains(const LinAl::Vector<T, D> &point) const
 111 {
 112         return shape->contains(inverse_trans.transform(point));
 113 }
 114
 115 template<typename T, unsigned D>
 116 inline Ray<T, D> TransformedShape<T, D>::make_local_ray(const Ray<T, D> &ray) const
 117 {
 118         LinAl::Vector<T, D> local_dir = inverse_trans.transform_linear(ray.get_direction());
 119         float distortion = local_dir.norm();
 120         return Ray<T, D>(inverse_trans.transform(ray.get_start()), local_dir, ray.get_limit()*distortion);
 121 }
 122
 123 template<typename T, unsigned D>
 124 inline unsigned TransformedShape<T, D>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
 125 {
 126         Ray<T, D> local_ray = make_local_ray(ray);
 127
 128         unsigned count = shape->get_intersections(local_ray, points, size);
 129         if(points)
 130         {
 131                 for(unsigned i=0; i<count; ++i)
 132                 {
 133                         points[i].position = transformation.transform(points[i].position);
 134                         /* XXX This is not correct for nonuniform scaling.  Inverse of the
 135                         transpose of the upper DxD part of the matrix should be used. */
 136                         points[i].normal = transformation.transform_linear(points[i].normal);
 137                         points[i].distance = inner_product(points[i].position-ray.get_start(), ray.get_direction());
 138                 }
 139         }
 140         return count;
 141 }
 142
 143 } // namespace Geometry
 144 } // namespace Msp
 145
 146 #endif