Basic Game Logic - 3D Game Development Practical Introduction - page 164

We can have coins with different amounts, by setting the value of coinValue . Just like
Collectable , Start() and Update() functions are empty. The new function we add to this
script is Collected , which takes a value of type Collector . This owner is in fact the collector
who is trying to collect this coin. Back to Collectable script (Listing 26 in page 76), recall
that Collectable sends a message to other scripts to inform them about a collision with a
collector. That message is called Collected and includes an attachment, which is the collect-
or. By declaring the method called Collected() and giving it the parameter owner , we spe-
cify Coin script as a receiver of this message. Consequently, when Collected message is re-
ceived, Collected() function is executed. What does this function do is to get the inventory
box of the collector ( owner ). By calling owner.GetComponent<InventoryBox>() , we try to
get a reference to the inventory box, and store this reference in box . If no inventory box
found, the value of box becomes null , and hence nothing is done. However, if the inventory
box exists, the amount of money inside that box is increased by coinValue. Finally, the coin
game object is destroyed.

Illustration 36 illustrates the interactions between Collector , Collectable , Coin , and

CategotyBox , along with all interactions among these scripts.