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 {@link #INTERSECT} for spheres that do not intersect the frustum.
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
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 {@link #INTERSECT} for spheres that do not intersect the frustum. 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