Randomising Item Drops

An introduction to using Arrays in Unity

In this article, you’ll start learning about effectively storing lists of data by using an Array, and how to retrieve set or random data from that Array.

Prelude

Now that we have a couple Items to drop, let’s see how we can store and access them effectively.

This is how we spawn an Item currently:

Right before destroying the Object we Instantiate an Item Drop.

But, we have a lot more Item Drops. What we could do is assign an ID to each referenced power-up, and activate the corresponding logic:

For each ID we have a bracket of code.

Or not …, because Unity provides much cleaner and more effective ways to store lists of data. One way is to make use of an Array.

Array

An Array stores a sequential collection of values of the same type and we can use it to store lists of values in a single variable.

We declare an Array by saying what type of data will be stored in the Array, immediately closed by a square bracket, [ ]. We can store different types of data as long as they are of the same type. The size of the Array is set during the assignment.

There are different ways we can declare an Array:

A few examples:

GameObject.FindGameObjectsWithTag is a special built-in Unity function that takes a string parameter(tag) and returns an array of GameObjects using this tag.

Use Example: Find GameObjects with Tag

Retrieving data from the Array

To retrieve data from the Array we first need to declare the Array name, followed by square brackets enclosing a integer value that’s called the index. The index indicates the element position in the Array. If we were to retrieve a specific element in the Array we simply have to declare its integer value (after having them manually assigned in the Inspector in our case).

myArray[index];

So if we’d like to retrieve a specific item drop, we could say the following (the order must match though):

Retrieve element by index number

To get the size of the Array we can use the following keyword:

Array.Length

Randomising the Index

Not only can we access an element by its index, since we have the ability to pass in an integer for now we might as well set the index to a random value ranging from the first element to the last element in the Array.

Conclusion

We’ve learned how to use an Array and how to randomise the index number. Now each time an entity is destroyed, a random item is dropped.

Note that there are different Array Types (javascript, C#, Built-in, …) and that there are other ways to store lists of data, for example by using a List, Arraylist or dictionaries and hash-tables. In time we’ll be examining the usage of these as well, but for the sake of this article it’ll suffice for now knowing how a basic Built-in Array works.

In the following article I’ll be introducing a new Weapon for the Player, the Triple Laser.

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Software Engineer — Unity Game and Application Developer

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Gert Coppens

Gert Coppens

Software Engineer — Unity Game and Application Developer

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