They both look similar and behave similarly, what's then the difference between OnTriggerEnter and OnCollisionEnter? The key to understand this is in knowing what are triggers in Unity.

“ontriggerenter2d” Code Answer. Whatever by Sore Starling on Dec 14 2020 Donate. 0 ontriggerenter2d. Csharp by on Jan 11 2021 Donate. C# queries related to “ontriggerenter2d” ontriggerenter2d unity; ontriggerenter2d api; ontriggerenter2d. Trigger触发，取消所有的物理碰撞，可以在触发时执行OnTrigger事件。 想获得碰撞状态信息，又不想触发物理效果 使用OnTrigger; 至少一方勾选 Ttigger触发器; 运动一方必须含有刚体.

In Unity, an object might be controlled by the physics engine or by script. If you need to control an object by script but still would like to know if an object touched another, a 'collision' happened, you need to use triggers.

Collision is under quotes because, strictly under Unity's terminology, a collision only happens when object's movements are governed by the physics engine, for the other cases what we have are simply objects touching each other, also, for such event, our script can be alerted as well.

What are triggers

A trigger is a collider that's not influenced by the physics engine. It doesn't respond to forces nor gravity. But they still do have a use for the physics engine, they are used to detect whether an object passed through another. Triggers are everywhere in Unity game development, and in other engines too to be honest.

Unity Trigger 2d

This Reaper is controlled by a simple back-and-forth walk AI, the physics engine is not used, but we still want to know when it has touched some things in the stage. For that, we can use an OnTriggerEnter

Collisions

A collision is also the result of an object touching another one, but instead of passing through, these objects push each other in a realistic way. Use OnCollisionEnter when your rigidbody colliders aren't triggers and you'd like to know when they touched each other.

For more information on how to create and use triggers, please see the official documentation on the subject. If you followed the documentation and something with your collision detection is not working, you may try to fix it using our comprehensive collision fixing tutorial.

TLDR;

Use triggers if you don't want/need the physics engine to control your object but still need to know if an object passed through another or reached some `zone` within the game. In that case, you'll use OnTriggerEnter().

Unity Void Ontriggerenter2d(collider2d Other)

If your object is indeed controlled by the physics engine, you'll use OnCollisionEnter() to know if an object touched another one.