Unity Editor Scene view

Checking the type of GameObject you are colliding with in Unity

In any given game, you are probably going to find dozens, if not hundreds of different objects colliding or intersecting with one another. Hence, one of the first things you learn in Unity is how to identify the type of object you have touched. These are the most common ways to do so among beginners:

void OnTriggerEnter(Collider other) {
     // If a GameObject has an "Enemy" tag, remove him. 
    if(other.tag == "Enemy") {
        Destroy(other.gameObject);
    }
}
void OnCollisionEnter(Collision collisionData) {
    // If a GameObject has an "Enemy" tag, remove him.
    if(collisionData.collider.tag == "Enemy") {
        Destroy(other.gameObject);
    }
} 

Essentially, the idea is checking whether the object we are colliding with or touching has been labelled with an Enemy tag, before we perform any action on the object.

Where tags are assigned.
Image source: Unity Manual: Tags

While it is simple and easy-to-understand, there are better ways of identifying objects we are colliding with.

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Collision Detection Modes in Unity

Collision detection modes in Unity’s Rigidbody component

Update (14 August 2020): Looking for an article on the Interpolate property on Unity Rigidbodies? We’ve put one together recently, so have a look here.

It isn’t particularly difficult to set up physics-based movement for objects in Unity — simply add a Rigidbody component onto an object that has a Collider component, and you’ll have yourself an object that moves and collides realistically with other objects.

Discrete collision
This was set up in 10 minutes.

If you start having fast-moving objects however, you might start to see these objects tunnel through obstacles.

Discrete collision tunnelling
Just like quantum physics. Sort of.
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