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⭐ Lesson 5.4: Building a Collectible

Let's combine everything from this module into one satisfying game object: a collectible that spins to catch the eye, waits patiently, and pops out of existence the moment the player touches it. This is a real piece of your mini-game.

🎯 Learning Objectives

  • Assemble a collectible from a mesh, a trigger collider, and scripts
  • Make it spin for visual appeal
  • Collect it on player touch and turn it into a reusable prefab
  • Prepare the hook for scoring (built fully in Module 6)

Estimated Time: 40 minutes

Project: A finished, reusable collectible prefab.

In This Lesson

Building the Object

Our collectible will be a small tilted cube — bright, spinning, and pickup-able. Here it is beside the player:

A real Unity render of a blue capsule player beside a tilted yellow cube collectible on a floor.
Figure 1: The collectible (yellow) and player (real render). We'll make the cube spin and vanish on contact.
  1. Add a Cube, scale it to about (0.6, 0.6, 0.6), and give it a bright material (Lesson 2.3).
  2. Raise it to Position Y ≈ 0.8 so it floats just off the floor.
  3. On its Box Collider, tick Is Trigger (Lesson 5.2).
  4. Rename it Collectible.

Making It Spin

A spinning pickup reads as "grab me!" Reuse the spin idea from Lesson 3.3. Create a Collectible script:

using UnityEngine;

public class Collectible : MonoBehaviour
{
    public float spinSpeed = 90f;   // degrees per second

    void Update()
    {
        // gentle spin around Y for visual appeal
        transform.Rotate(0f, spinSpeed * Time.deltaTime, 0f);
    }
}

Collecting It

Now add the pickup behaviour to the same script — when the player enters the trigger, collect it. We'll print a message for now and wire real scoring in Module 6:

using UnityEngine;

public class Collectible : MonoBehaviour
{
    public float spinSpeed = 90f;

    void Update()
    {
        transform.Rotate(0f, spinSpeed * Time.deltaTime, 0f);
    }

    void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Player"))
        {
            Debug.Log("Collected! (score will go here in Module 6)");
            Destroy(gameObject);   // remove this collectible
        }
    }
}

⚠️ The three must-haves

For the pickup to fire: the collectible's collider has Is Trigger ON, the player has a Rigidbody, and the player is tagged "Player". Miss one and nothing happens — this is the checklist to run every time.

Turn It Into a Prefab

You'll want many collectibles, so make it a prefab (Lesson 2.4):

  1. Drag the finished Collectible from the Hierarchy into a Prefabs folder.
  2. Drag the prefab back into the scene several times to scatter collectibles around.
  3. Later, tweak the prefab once (e.g. change spinSpeed) and every collectible updates.
graph TD A[Collectible object] --> B[Mesh + bright material] A --> C[Box Collider: Is Trigger ON] A --> D[Collectible.cs: spin + collect] A --> E[Saved as Prefab] --> F[Scatter many instances]

Hands-on Exercise

🏋️ Exercise: A field of stars

  1. Build the spinning, collectible cube with the full Collectible script.
  2. Confirm it spins and disappears when the player (tagged, with Rigidbody) touches it.
  3. Make it a prefab and scatter 5–6 around the floor.
  4. Play and collect them all — each vanishes and logs a message.
💡 It spins but won't collect

Run the three-must-haves checklist above. Almost always it's a missing Rigidbody on the player or a missing "Player" tag.

✅ Bonus: bob while spinning 
void Update()
{
    transform.Rotate(0f, spinSpeed * Time.deltaTime, 0f);
    float y = 0.8f + Mathf.Sin(Time.time * 2f) * 0.15f;
    transform.position = new Vector3(transform.position.x, y, transform.position.z);
}

🎯 Quick Quiz

Question 1: Why make the collectible a prefab?

Question 2: The collectible spins but never gets collected. What's the most likely miss?

Summary

🎉 Key Takeaways

  • A collectible = mesh + bright material + trigger collider + a script.
  • Spin it in Update for appeal; collect it in OnTriggerEnter with a tag check + Destroy.
  • Save it as a prefab to scatter many and edit them all at once.
  • The scoring hook is ready — we complete it in Module 6.

🚀 What's Next?

Collecting things is satisfying — but players need to see their progress. Module 6 adds on-screen UI, a live score, and sound.

🎉 Module 5 complete!

Gravity, colliders, triggers, and a real working collectible. Your game is taking shape.