Test 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 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 <code>true</code> if the given sphere is partly or completely inside the frustum;
<code>false</code> otherwise
Test 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 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 <code>true</code> if the given sphere is partly or completely inside the frustum; <code>false</code> otherwise