* @return Pushable block count, -1 if the amount exceeds the limit
*/
public int getExtendableLength(Block block) {
final int maxlength = 13;
BlockFace face = this.getFacing(block);
MoveReaction reaction;
for (int i = 0; i < maxlength; i++) {
block = block.translate(face);
reaction = getReaction(block);
if (reaction == MoveReaction.DENY) {
return -1; //blocked