Use the coverage function to calculate tighter bounding boxes

[libs/math.git] / source / geometry / hypersphere.h

diff --git a/source/geometry/hypersphere.h b/source/geometry/hypersphere.h
index f95ebe4182094667533e2cec0914210cb7b79337..13e4278430b8b5e2a811974a1959d54dac8bd305 100644 (file)
--- a/source/geometry/hypersphere.h
+++ b/source/geometry/hypersphere.h
@@ -1,15 +1,18 @@
 #ifndef MSP_GEOMETRY_HYPERSPHERE_H_
 #define MSP_GEOMETRY_HYPERSPHERE_H_
 
+#include <cmath>
+#include <stdexcept>
 #include <msp/linal/vector.h>
-#include "hyperbox.h"
-#include "ray.h"
 #include "shape.h"
-#include "surfacepoint.h"
 
 namespace Msp {
 namespace Geometry {
 
+/**
+A shape consisting of the points within a specific distance from the origin.
+Two- and three-dimensional cases are Circle and Sphere, respectively.
+*/
 template<typename T, unsigned D>
 class HyperSphere: public Shape<T, D>
 {
@@ -17,29 +20,27 @@ private:
        T radius;
 
 public:
-       HyperSphere();
+       HyperSphere(): radius(1) { }
        explicit HyperSphere(T);
 
        virtual HyperSphere *clone() const;
 
        T get_radius() const { return radius; }
 
-       virtual HyperBox<T, D> get_axis_aligned_bounding_box() const;
+       virtual BoundingBox<T, D> get_axis_aligned_bounding_box(unsigned = 0) const;
        virtual bool contains(const LinAl::Vector<T, D> &) const;
-       virtual bool check_intersection(const Ray<T, D> &) const;
        virtual unsigned get_max_ray_intersections() const { return 2; }
        virtual unsigned get_intersections(const Ray<T, D> &, SurfacePoint<T, D> *, unsigned) const;
+       virtual Coverage get_coverage(const BoundingBox<T, D> &) const;
 };
 
-template<typename T, unsigned D>
-inline HyperSphere<T, D>::HyperSphere():
-       radius(1)
-{ }
-
 template<typename T, unsigned D>
 inline HyperSphere<T, D>::HyperSphere(T r):
        radius(r)
-{ }
+{
+       if(r<=T(0))
+               throw std::invalid_argument("HyperSphere::HyperShpere");
+}
 
 template<typename T, unsigned D>
 inline HyperSphere<T, D> *HyperSphere<T, D>::clone() const
@@ -48,12 +49,12 @@ inline HyperSphere<T, D> *HyperSphere<T, D>::clone() const
 }
 
 template<typename T, unsigned D>
-inline HyperBox<T, D> HyperSphere<T, D>::get_axis_aligned_bounding_box() const
+inline BoundingBox<T, D> HyperSphere<T, D>::get_axis_aligned_bounding_box(unsigned) const
 {
-       LinAl::Vector<T, D> dimensions;
+       LinAl::Vector<T, D> extent;
        for(unsigned i=0; i<D; ++i)
-               dimensions[i] = radius;
-       return HyperBox<T, D>(dimensions);
+               extent[i] = radius;
+       return BoundingBox<T, D>(-extent, extent);
 }
 
 template<typename T, unsigned D>
@@ -62,47 +63,74 @@ inline bool HyperSphere<T, D>::contains(const LinAl::Vector<T, D> &point) const
        return inner_product(point, point)<=radius*radius;
 }
 
-template<typename T, unsigned D>
-inline bool HyperSphere<T, D>::check_intersection(const Ray<T, D> &ray) const
-{
-       T x = inner_product(ray.get_direction(), ray.get_start());
-       if(x>0)
-               return contains(ray.get_start());
-       else
-               return contains(ray.get_start()-ray.get_direction()*x);
-}
-
 template<typename T, unsigned D>
 inline unsigned HyperSphere<T, D>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
 {
+       using std::sqrt;
+
        T mid = -inner_product(ray.get_direction(), ray.get_start());
        LinAl::Vector<T, D> nearest = ray.get_start()+ray.get_direction()*mid;
        T offset_sq = radius*radius-inner_product(nearest, nearest);
-       if(offset_sq<0)
+       if(offset_sq<T(0))
                return 0;
        T offset = sqrt(offset_sq);
 
        unsigned n = 0;
-       for(int i=-1; i<=1; i+=2)
+       for(int i=-1; (n<size && i<=1); i+=2)
        {
                T x = mid+offset*i;
-               if(x>0 && n<size)
+               if(ray.check_limits(x))
                {
                        if(points)
                        {
                                points[n].position = ray.get_start()+ray.get_direction()*x;
                                points[n].normal = normalize(points[n].position);
+                               points[n].distance = x;
+                               points[n].entry = (i<0);
                        }
 
                        ++n;
-                       if(n==size)
-                               return n;
                }
        }
 
        return n;
 }
 
+template<typename T, unsigned D>
+inline Coverage HyperSphere<T, D>::get_coverage(const BoundingBox<T, D> &bbox) const
+{
+       const LinAl::Vector<T, D> &min_pt = bbox.get_minimum_point();
+       const LinAl::Vector<T, D> &max_pt = bbox.get_maximum_point();
+
+       LinAl::Vector<T, D> far_point;
+       for(unsigned i=0; i<D; ++i)
+               far_point[i] = std::max(std::abs(min_pt[i]), std::abs(max_pt[i]));
+
+       if(contains(far_point))
+               return FULL_COVERAGE;
+
+       unsigned spanned_dimensions = 0;
+       for(unsigned i=0; i<D; ++i)
+               if(min_pt[i]<T(0) && max_pt[i]>T(0))
+                       spanned_dimensions |= 1<<i;
+
+       for(unsigned i=0; i<(1<<D); ++i)
+       {
+               if(i&spanned_dimensions)
+                       continue;
+
+               LinAl::Vector<T, D> point;
+               for(unsigned j=0; j<D; ++j)
+                       if(!((spanned_dimensions>>j)&1))
+                               point[j] = ((i>>j)&1 ? max_pt[j] : min_pt[j]);
+
+               if(contains(point))
+                       return PARTIAL_COVERAGE;
+       }
+
+       return NO_COVERAGE;
+}
+
 } // namespace Geometry
 } // namespace Msp