Trigger vs collision detection in Unity - Hands-On Comparison

Trigger vs Collision Detection in Unity

📖 Scenario: You are creating a simple Unity scene where a player cube moves and interacts with objects. You want to learn the difference between triggers and collisions by setting up two cubes: one that detects collisions and one that detects triggers.

🎯 Goal: Build a Unity script that detects when the player cube collides with a solid cube and when it enters a trigger cube. You will set up the data, configure the colliders, write the detection logic, and complete the script to show messages in the Unity Console.

📋 What You'll Learn

Create a player GameObject with a Rigidbody and BoxCollider

Create two cubes: one with a BoxCollider (collision) and one with a BoxCollider set as trigger

Write a C# script with OnCollisionEnter and OnTriggerEnter methods

Print distinct messages to the Console for collision and trigger events

💡 Why This Matters

🌍 Real World

Games and interactive apps often need to detect when objects touch or overlap. Understanding triggers and collisions helps create realistic and responsive behaviors.

💼 Career

Game developers and interactive media programmers use collision and trigger detection daily to build gameplay mechanics and user interactions.

1

Setup Player and Cubes

Create a GameObject called player with a Rigidbody and a BoxCollider. Also create two cubes named solidCube and triggerCube with BoxCollider components. Do not set any collider as trigger yet.

Unity

// Create player GameObject with Rigidbody and BoxCollider
// Create solidCube and triggerCube GameObjects with BoxCollider components
// Your code here

Need a hint?

Use new GameObject("player") to create the player and add components with AddComponent<T>(). Use CreatePrimitive(PrimitiveType.Cube) for the cubes.

2

Configure Trigger Collider

Set the BoxCollider on triggerCube to be a trigger by setting its isTrigger property to true.

Unity

// Player setup
GameObject player = new GameObject("player");
player.AddComponent();
player.AddComponent();

// Solid cube setup
GameObject solidCube = GameObject.CreatePrimitive(PrimitiveType.Cube);
solidCube.name = "solidCube";

// Trigger cube setup
GameObject triggerCube = GameObject.CreatePrimitive(PrimitiveType.Cube);
triggerCube.name = "triggerCube";

// Set triggerCube collider to trigger
// Your code here

Need a hint?

Use GetComponent<BoxCollider>() on triggerCube and set isTrigger = true.

3

Write Collision and Trigger Detection Methods

Create a C# script called PlayerCollisionDetector with OnCollisionEnter(Collision collision) and OnTriggerEnter(Collider other) methods. In OnCollisionEnter, print "Collision with solidCube detected" if the collided object is solidCube. In OnTriggerEnter, print "Trigger entered with triggerCube" if the other collider is triggerCube.

Unity

using UnityEngine;

public class PlayerCollisionDetector : MonoBehaviour
{
    // Add OnCollisionEnter method
    // Add OnTriggerEnter method
    // Your code here
}

Need a hint?

Use OnCollisionEnter(Collision collision) and OnTriggerEnter(Collider other) methods. Check the gameObject.name to identify the cubes and use Debug.Log() to print messages.

4

Attach Script and Finalize Setup

Attach the PlayerCollisionDetector script to the player GameObject. Position the solidCube and triggerCube near the player so that moving the player will cause collision and trigger events.

Unity

using UnityEngine;

public class PlayerCollisionDetector : MonoBehaviour
{
    void OnCollisionEnter(Collision collision)
    {
        if (collision.gameObject.name == "solidCube")
        {
            Debug.Log("Collision with solidCube detected");
        }
    }

    void OnTriggerEnter(Collider other)
    {
        if (other.gameObject.name == "triggerCube")
        {
            Debug.Log("Trigger entered with triggerCube");
        }
    }
}

// Attach PlayerCollisionDetector script to player
// Position solidCube and triggerCube near player
// Your code here

Need a hint?

Use AddComponent<PlayerCollisionDetector>() on player. Set positions of solidCube and triggerCube so they are near the player.