sphere_sphere-inl.h

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#ifndef FCL_NARROWPHASE_DETAIL_SPHERESPHERE_INL_H
#define FCL_NARROWPHASE_DETAIL_SPHERESPHERE_INL_H

#include "fcl/narrowphase/detail/primitive_shape_algorithm/sphere_sphere.h"

namespace fcl
{

namespace detail
{

//==============================================================================
extern template
bool sphereSphereIntersect(const Sphere<double>& s1, const Transform3<double>& tf1,
                           const Sphere<double>& s2, const Transform3<double>& tf2,
                           std::vector<ContactPoint<double>>* contacts);

//==============================================================================
extern template
bool sphereSphereDistance(const Sphere<double>& s1, const Transform3<double>& tf1,
                          const Sphere<double>& s2, const Transform3<double>& tf2,
                          double* dist, Vector3<double>* p1, Vector3<double>* p2);

//==============================================================================
template <typename S>
bool sphereSphereIntersect(const Sphere<S>& s1, const Transform3<S>& tf1,
                           const Sphere<S>& s2, const Transform3<S>& tf2,
                           std::vector<ContactPoint<S>>* contacts)
{
  Vector3<S> diff = tf2.translation() - tf1.translation();
  S len = diff.norm();
  if(len > s1.radius + s2.radius)
    return false;

  if(contacts)
  {
    // If the centers of two sphere are at the same position, the normal is (0, 0, 0).
    // Otherwise, normal is pointing from center of object 1 to center of object 2
    const Vector3<S> normal = len > 0 ? (diff / len).eval() : diff;
    const Vector3<S> point = tf1.translation() + diff * s1.radius / (s1.radius + s2.radius);
    const S penetration_depth = s1.radius + s2.radius - len;
    contacts->emplace_back(normal, point, penetration_depth);
  }

  return true;
}

//==============================================================================
template <typename S>
bool sphereSphereDistance(const Sphere<S>& s1, const Transform3<S>& tf1,
                          const Sphere<S>& s2, const Transform3<S>& tf2,
                          S* dist, Vector3<S>* p1, Vector3<S>* p2)
{
  Vector3<S> o1 = tf1.translation();
  Vector3<S> o2 = tf2.translation();
  Vector3<S> diff = o1 - o2;
  S len = diff.norm();
  if(len > s1.radius + s2.radius)
  {
    if(dist) *dist = len - (s1.radius + s2.radius);
    if(p1) *p1 = tf1.inverse(Eigen::Isometry) * (o1 - diff * (s1.radius / len));
    if(p2) *p2 = tf2.inverse(Eigen::Isometry) * (o2 + diff * (s2.radius / len));
    return true;
  }

  if(dist) *dist = -1;
  return false;
}

} // namespace detail
} // namespace fcl

#endif