The universally unique identifier(UUID) of this object
What to do after hit.
How the enemy fire bullets.
Test if the object collide with another object o.
Actions invoked after the entity is dead.
If the entity is dead.
How the entity move.
Render the object.
Render other textures of the enemy.
The shape of the entity, used for collide test.
The key of enemy texture.
Check the state of the object, and if this need to be removed, true should be returned.
The X coordinate of the enemy in Double.