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intersect.h
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intersect.h：Code Content
  1. // intersect.h
  2. //
  3. // Copyright (C) 2002, Chris Laurel <claurel@shatters.net>
  4. //
  5. // Intersection calculation for various geometric objects.
  6. //
  7. // This program is free software; you can redistribute it and/or
  8. // modify it under the terms of the GNU General Public License
  9. // as published by the Free Software Foundation; either version 2
  10. // of the License, or (at your option) any later version.
  12. #ifndef _CELMATH_INTERSECT_H_
  13. #define _CELMATH_INTERSECT_H_
  15. #include "ray.h"
  16. #include "sphere.h"
  17. #include "ellipsoid.h"
  20. template<class T> bool testIntersection(const Ray3<T>& ray,
  21.                                         const Sphere<T>& sphere,
  22.                                         T& distance)
  23. {
  24.     Vector3<T> diff = ray.origin - sphere.center;
  25.     T s = (T) 1.0 / square(sphere.radius);
  26.     T a = ray.direction * ray.direction * s;
  27.     T b = ray.direction * diff * s;
  28.     T c = diff * diff * s - (T) 1.0;
  29.     T disc = b * b - a * c;
  30.     if (disc < 0.0)
  31.         return false;
  33.     disc = (T) sqrt(disc);
  34.     T sol0 = (-b + disc) / a;
  35.     T sol1 = (-b - disc) / a;
  37.     if (sol0 > 0)
  38.     {
  39.         if (sol0 < sol1 || sol1 < 0)
  40.             distance = sol0;
  41.         else
  42.             distance = sol1;
  43.         return true;
  44.     }
  45.     else if (sol1 > 0)
  46.     {
  47.         distance = sol1;
  48.         return true;
  49.     }
  50.     else
  51.     {
  52.         return false;
  53.     }
  54. }
  57. template<class T> bool testIntersection(const Ray3<T>& ray,
  58.                                         const Sphere<T>& sphere,
  59.                                         T& distanceToTester,
  60.                                         T& cosAngleToCenter)
  61. {
  62.     if (testIntersection(ray, sphere, distanceToTester))
  63.     {
  64.         cosAngleToCenter    = (sphere.center - ray.origin)*ray.direction/(sphere.center - ray.origin).length();
  65.         return true;
  66.     }
  67.     return false;
  68. }
  71. template<class T> bool testIntersection(const Ray3<T>& ray,
  72.                                         const Ellipsoid<T>& e,
  73.                                         T& distance)
  74. {
  75.     Vector3<T> diff = ray.origin - e.center;
  76.     Vector3<T> s((T) 1.0 / square(e.axes.x),
  77.                  (T) 1.0 / square(e.axes.y),
  78.                  (T) 1.0 / square(e.axes.z));
  79.     Vector3<T> sdir(ray.direction.x * s.x,
  80.                     ray.direction.y * s.y,
  81.                     ray.direction.z * s.z);
  82.     Vector3<T> sdiff(diff.x * s.x, diff.y * s.y, diff.z * s.z);
  83.     T a = ray.direction * sdir;
  84.     T b = ray.direction * sdiff;
  85.     T c = diff * sdiff - (T) 1.0;
  86.     T disc = b * b - a * c;
  87.     if (disc < 0.0)
  88.         return false;
  90.     disc = (T) sqrt(disc);
  91.     T sol0 = (-b + disc) / a;
  92.     T sol1 = (-b - disc) / a;
  94.     if (sol0 > 0)
  95.     {
  96.         if (sol0 < sol1 || sol1 < 0)
  97.             distance = sol0;
  98.         else
  99.             distance = sol1;
  100.         return true;
  101.     }
  102.     else if (sol1 > 0)
  103.     {
  104.         distance = sol1;
  105.         return true;
  106.     }
  107.     else
  108.     {
  109.         return false;
  110.     }
  111. }
  114. template<class T> bool testIntersection(const Ray3<T>& ray,
  115.                                         const Ellipsoid<T>& ellipsoid,
  116.                                         T& distanceToTester,
  117.                                         T& cosAngleToCenter)
  118. {
  119.     if (testIntersection(ray, ellipsoid, distanceToTester))
  120.     {
  121.         cosAngleToCenter  = (ellipsoid.center - ray.origin)*ray.direction/(ellipsoid.center - ray.origin).length();
  122.         return true;
  123.     }
  124.     return false;
  125. }
  127. #endif // _CELMATH_INTERSECT_H_