Beginner 2D UFO Game 6 of 9: Creating Collectable Objects - Unity Official Tutorials

So far we have created a play field

and a Player game object

and we have the player moving

under our control.

In this lesson we'll create

the collectable objects

for our player to pick up.

First open the Sprites folder.

Drag the sprite Pickup

in to the hierarchy.

You'll notice after dragging in

the Pickup sprite that we

still can't see it.

That's because it's being rendered

behind both the Player

and Background sprites.

To bring it forward we

need to set the sorting layer

in the sprite renderer component.

Set the sorting layer to Pickups.

Now the Player game object

is still in the way.

This is because the Player

sorting layer is in front

of the Pickups sorting layer.

Let's temporarily deactivate

the Player game object.

Select the Player game object

and deselect the checkbox

in front of the Name field.

This is the game object's Active checkbox.

Deselecting it will deactivate

the game object in the scene.

This will give us a clear working space

for our new pickup object

which we can now see.

Focus the scene view camera on the

pickup object by highlighting it

and pressing the F key whilst

the cursor is over the scene view.

So that we can collide with the pickup

let's add a circle collider 2D

component to it.

With the pickup highlighted click

Add Component - Physics 2D

then Circle Collider 2D.

Adjust the Radius property

of the circle collider 2D

so that it fits the sprite artwork visually b

by dragging in the Radius field.

To be effective the collectable

must attract the attention of the player.

So let's make the object more attractive.

There's one thing I feel certainly

attracts the attention of a player

and that is movement.

So let's rotate our pickup.

One way to do this is with a script.

With the pickup object still selected

use the Add Component button

in the inspector.

Let's create a new script called Rotator.

Click Create and Add to confirm

and let's organise the script by

placing it in the Scripts folder.

Open the Scripts folder and

double click to open it for editing.

We want the sprite to spin and we want

to do it with this script.

Let's remove the sample code

we don't need.

We will not be using forces

so we can use Update

rather than Fixed Update.

We want to rotate the object every frame.

To make the pickups spin we

don't want to set the transform rotation

but we want to rotate the transform.

Type Transform inside Update.

Select it and hold down the

control key on windows or the command

key on mac and type '

Again this brings up the page

with a search term Transform.

Select Transform.

Scroll down until you see Transform's public functions.

There are two main ways to affect the transform.

These are Translate and Rotate.

Translate moves the game object

using it's transform.

Rotate rotates the game object

using it's transform.

We will use rotate.

So let's click on the link.

This brings up the page for Transform.Rotate.

Note again the two signatures.

One is using a vector3

and the other is using 3

float values for X, Y or Z.

Both have the optional parameter

Space which we will

leave at default for this lesson.

Again we will choose the most simple

form that only uses the vector3 for direction.

Let's return to our code.

After transform,

making sure that transform is written to

begin with a lowercase t,

write .rotate (new Vector3 (0, 0, 45))

This means we'll rotate

around the Z axis.

Now this action also needs

to be smooth and frame rate independent

so we need to multiply the vector3 value

by Time.deltaTime.

It is worth noting that even

though we are working with a 2D

sprite we are using a vector3

to rotate the collectable's transform.

This is because the transform

of the 2D sprite

still exists in the 3D volume.

When using the transform component

with 2D objects we simply

ignore the axis we don't need.

Now that we are done with our Rotator script

save this script and return to Unity.

Let's test by entering play mode.

And we can see our pickup object rotates.

Let's exit play mode.

Okay, we have the start of a working

pickup object.

Next we want to place these pickups

around the game area.

But before we do this we need to do

one important step.

We need to make our pickup object

in to a prefab.

Remember, a prefab is an

asset that contains a template

or blueprint of a game object

or game object family.

We create a prefab from an

existing game object or game object family

and once we create it

we can use it in any scene

in our current project.

With a prefab of our pickup object

we will be able to make changes to

a single instance in our scene

or to the prefab asset itself.

And all of the pickup objects in our

game will be updated with those changes.

You'll notice we already have a folder

to hold our prefabs.

Let's drag the Pickup game object

from our hierarchy and place

it in to our Prefabs folder.

When we drag and item from our hierarchy

in to our project view

we create a new prefab

asset in our project.

Before we spread our collectables

around the game area we should create

a new game object

to hold our pickups and

to help organise our hierarchy.

Let's create a new game object.

And call it Pickups.

Check the transform to make sure our

Pickups holder object

is at origin, or (0, 0, 0).

And if not use the component

context menu to reset it.

Next drag our Pickup game object on to it.

Now we want to spread a

number of these pickup objects

around the play area.

Make sure the pickup game object is

selected, and not the parent.

Now let's back out a little

so we can see the entire game area.

Click and drag the pickup game object

to move it in to the

first pickup position.

I'm going to place mine at the top of the playing area.

With the game object still selected

duplicate it.

This can be done either by selecting

Edit - Duplicate, or by using the hot key combination.

This is command-D on mac,

or control-D on windows.

Now let's position the

second instance of the prefab.

Using the hot keys we will

create a few more, placing them

around the play area.

Okay, I've created 12.

Let's hit play and test.

Excellent, these pickup prefabs

are working great.

In the next assignment we'll learn how to

pick them up and to count them.