Setting up the Game

Moving the Player

Moving the Camera

Setting up the Play Area

Creating Collectibles

Detecting Collisions with Collectibles

Displaying Score and Text

Adding AI Navigation

Building the Game

Welcome to 3D Beginner: Roll-a-Ball Game! In this learning project, you’ll:  

Use Unity Editor and its built-in capabilities to set up a simple game environment

Write your own custom scripts to create the game functionality

Create a basic user interface to improve the game experience

Build your game, so other people can play it!

3D Beginner: Roll-a-Ball Game

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Overview

Disable PickUps with OnTriggerEnter

Add a tag to the PickUp Prefab

Write a conditional statement

Set the Pickup Colliders as triggers

Add a Rigidbody component to the PickUp Prefab

Final script sample

Unity_RollABall_6-2.mp4

Unity_RollABall_6-3.mp4

Unity_RollABall_6-4.mp4

Unity_RollABall_6-5.mp4

Unity_RollABall_6-1.mp4

6.4-final-pickups-working.mp4

Revise your PlayerController script to make PickUpGameObjects disappear when they collide with the Player sphere

Tag PickUp GameObjects and write conditional statements to make sure they’re the only things that disappear

Set the Prefab PickUp Collider as a trigger and add a Rigidbody component, to make the collectibles work properly

Disable_PickUps_with_OnTriggerEnter-Transcript.txt

Add_a_tag_to_the_PickUp_Prefab-Transcript.txt

Write_a_conditional_statement-Transcript.txt

Set_the_PickUp_Colliders_as_triggers-Transcript.txt

Add_a_Rigidbody_component_to_the_PickUp_Prefab-Transcript.txt

Unit 2 - Program a basic game


By the end of this tutorial, your game will look something like this:

Follow the video or text instructions below to add the OnTriggerEnter function and set the other object as inactive inside that function:

Open the PlayerController script for editing.

Beneath the FixedUpdate function, add the following code:

   void OnTriggerEnter(Collider other) 
   {
   
   }

Add the following line of code inside the function body for OnTriggerEnter:

Note: Nothing new will happen in the game yet, since the PickUp GameObjects are not yet set up appropriately as triggers.

Follow the video or text instructions below to edit the PickUp prefab, create a new tag, and apply the tag to the prefab:

In the Project window, go to the Prefabs folder and select the PickUp prefab. 

Any changes you make to the prefab when you select it in the Project window will apply to all prefabs.


At the top of the Inspector window, from the Tag dropdown menu, select Add Tag. 

Select the Add (+) button to add a new tag, then name it “PickUp”. 

Important: This is case sensitive, so be careful — it needs to be exactly the same spelling and capitalization that you use in the script later on.


With the PickUp prefab still selected, use the Tag dropdown menu to select the new “PickUp” tag from the list. 

Double-check that the tag has been applied to all pickups in the scene by selecting them and making sure they have the “PickUp” tag applied.


Two images are shown side by side. On the left, the Tags and Layers window is shown in the Inspector window, with a new PickUp tag added to the Tags list. On the Right, the PickUp tag is applied to the PickUp prefab asset.

Follow the video or text instructions below to check for the “PickUp” tag, disable the objects if that condition is met, and save your script:

At the top of the function body for OnTriggerEnter, add the following IF statement:

       if (other.gameObject.CompareTag("PickUp")) 
       {
       
       }

2.  Disable the objects if that condition is met.

Cut and paste the line of code you already had into that IF statement:

       if (other.gameObject.CompareTag("PickUp")) 
       {
           other.gameObject.SetActive(false);
       }

Make sure to save your script before returning to Unity. 

Your entire OnTriggerEnter function should now look like this:

   void OnTriggerEnter (Collider other) 
   {
       if (other.gameObject.CompareTag("PickUp")) 
       {
           other.gameObject.SetActive(false);
       }
   }

Follow the video or text instructions below to change the pickups to triggers and test your game:

In the Prefabs folder, select the PickUp prefab.

In its Box Collider component, enable IsTrigger. 

Double-check that this change has been applied to the PickUp GameObjects in the Scene view.

Save the scene, then enter Play mode to test it. 

As the Player GameObject enters the trigger, the PickUp GameObjects should disappear!


In the Box Collider component for the PickUp prefab, the Is Trigger property is enabled.

Follow the video or text instructions below to add a Rigidbody component to the PickUp GameObjects, but disable physics calculations for optimization purposes:

1.  Add a Rigidbody component to the PickUp GameObjects.

In the Project window, go to the Prefabs folder and select the PickUp prefab.

In the Inspector window, select Add Component and add a Ridigbody component. 


In the Rigidbody component, disable Use Gravity and enable Is Kinematic.

Save the scene again and enter Play mode to test to make sure the game is still behaving as expected.

The Rigidbody component is shown with Use Gravity disabled and Is Kinematic enabled. 

If your script is not working as expected, below is an example of what your code should look like at this point. The comments have been added to make the code more readable. 


using UnityEngine;
using UnityEngine.InputSystem;

public class PlayerController : MonoBehaviour
{
 // Rigidbody of the player.
 private Rigidbody rb; 

 // Movement along X and Y axes.
 private float movementX;
 private float movementY;

 // Speed at which the player moves.
 public float speed = 0; 

 // Start is called before the first frame update.
 void Start()
    {
 // Get and store the Rigidbody component attached to the player.
        rb = GetComponent<Rigidbody>();
    }
 
 // This function is called when a move input is detected.
 void OnMove(InputValue movementValue)
    {
 // Convert the input value into a Vector2 for movement.
        Vector2 movementVector = movementValue.Get<Vector2>();

 // Store the X and Y components of the movement.
        movementX = movementVector.x; 
        movementY = movementVector.y; 
    }

 // FixedUpdate is called once per fixed frame-rate frame.
 private void FixedUpdate() 
    {
 // Create a 3D movement vector using the X and Y inputs.
        Vector3 movement = new Vector3 (movementX, 0.0f, movementY);

 // Apply force to the Rigidbody to move the player.
        rb.AddForce(movement * speed); 
    }

 void OnTriggerEnter(Collider other) 
    {
 // Check if the object the player collided with has the "PickUp" tag.
 if (other.gameObject.CompareTag("PickUp")) 
        {
 // Deactivate the collided object (making it disappear).
            other.gameObject.SetActive(false);
        }
    }


}

Detecting Collisions with Collectibles

1. Overview

2. Disable PickUps with OnTriggerEnter

3. Add a tag to the PickUp Prefab

4. Write a conditional statement

5. Set the Pickup Colliders as triggers

6. Add a Rigidbody component to the PickUp Prefab

7. Final script sample

Complete this tutorial