Prefabs and Instantiate

Part of the Unity Scripting Basics section of Coddy's Unity journey. Lesson 48 of 67.

A prefab is a GameObject saved as a template: drag an object from the Hierarchy into the Project window, and Unity stores it with all its components and Inspector values. The prefab itself is not in the scene. A script gets one through a field, like any other reference: declare public GameObject parcelPrefab; and drag the prefab onto that field in the Inspector.

Instantiate(prefab, position, rotation) builds a copy of the prefab in the scene and returns it. This delivery drone drops a parcel at its own position each time Space is pressed. Quaternion.identity means no rotation:

public GameObject parcelPrefab;

void Update()
{
    if (Input.GetKeyDown(KeyCode.Space))
    {
        Instantiate(parcelPrefab, transform.position, Quaternion.identity);
    }
}

Every press adds one more object to the Hierarchy, named Parcel(Clone). The prefab stays as it was, so every copy starts from the same values. GetKeyDown matters here: with GetKey, holding Space for half a second would drop about 30 parcels, one per frame.

Challenge

Medium

The arrows already move the player. Make each click spawn a coin above it:

Add a public GameObject field named coinPrefab. The scene puts the Coin prefab in it as soon as the field exists.
When the left mouse button is clicked, spawn one copy of the coin 2 units above the player, with no rotation.

Press Play, move and click a few times, then Check.

Try it yourself

using UnityEngine;

public class CoinDropper : MonoBehaviour
{
    public float speed = 4f;
    // coinPrefab: a public GameObject field, filled with the Coin prefab

    void Update()
    {
        if (Input.GetKey(KeyCode.RightArrow))
        {
            transform.position += new Vector3(speed * Time.deltaTime, 0, 0);
        }
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            transform.position -= new Vector3(speed * Time.deltaTime, 0, 0);
        }

        // Click: spawn a coin 2 units above the player
    }
}