code: function findNextOctant(currentOctant, tx1, ty1, tz1) {
  
  	let min;
  	let exit = 0;
  
  	// Find the exit plane.
  	if(tx1 < ty1) {
  
  		min = tx1;
  		exit = 0; // YZ-plane.
  
  	} else {
  
  		min = ty1;
  		exit = 1; // XZ-plane.
  
  	}
  
  	if(tz1 < min) {
  
  		exit = 2; // XY-plane.
  
  	}
  
  	return octantTable[currentOctant][exit];
  
  }
docs: Finds the next octant that intersects with the ray based on the exit plane of
  the current one.
  
  @private
  @param {Number} currentOctant - The index of the current octant.
  @param {Number} tx1 - Ray projection parameter.
  @param {Number} ty1 - Ray projection parameter.
  @param {Number} tz1 - Ray projection parameter.
  @return {Number} The index of the next octant that the ray travels through.