code: function cull(octant, region, result) {
  
  	const children = octant.children;
  
  	let i, l;
  
  	b.min = octant.min;
  	b.max = octant.max;
  
  	if(region.intersectsBox(b)) {
  
  		if(children !== null) {
  
  			for(i = 0, l = children.length; i < l; ++i) {
  
  				cull(children[i], region, result);
  
  			}
  
  		} else {
  
  			result.push(octant);
  
  		}
  
  	}
  
  }
docs: Recursively collects octants that lie inside the specified region.
  
  @private
  @param {Octant} octant - An octant.
  @param {Frustum|Box3} region - A region.
  @param {Octant[]} result - A list to be filled with octants that intersect with the region.