code: public int intersectSphere(Vector3fc center, float radius) {
          return intersectSphere(center.x(), center.y(), center.z(), radius);
      }
docs: Determine whether the given sphere is partly or completely within or outside of the frustum defined by <code>this</code> frustum culler.
  <p>
  The algorithm implemented by this method is conservative. This means that in certain circumstances a <i>false positive</i>
  can occur, when the method returns <code>true</code> for spheres that are actually not visible.
  See <a href="http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm">iquilezles.org</a> for an examination of this problem.
  
  @param center
  the sphere's center
  @param radius
  the sphere's radius
  @return {@link #INSIDE} if the given sphere is completely inside the frustum, or {@link #INTERSECT} if the sphere intersects
  the frustum, or {@link #OUTSIDE} if the sphere is outside of the frustum