Have Two Instantiated Prefab Clones That Collide, Want Only One To Stop Translating Its Transform

Making a 2D project involving cars that drive on a straight and 90 degree angle path. I have a spawn point Instantiating clones of a prefab car. After they spawn they have a movement script that translates their transform with a bool flag that determines moving forward verse being stopped.

The cars do a great job stopping when they collide but I'm having a terrible time trying to figure out how to get the cars moving again

I tried setting a random timer on a coroutine to trigger the drive bool which was great when the first prefab got the lower number but when the second one was lower it would run over the first one looking bad.

My paradox is that any code I throw at it effects both objects so I cant get one to start moving without the other hitting it again.

 

Using the translate function to override the transform on a gameObject might not be the best implantation here, that's because it totally disregards the use of the physics system, therefore you'll get no collision detection etc. I'd recommend firstly re-writing the logic so that it's using Unity's physics system, so applying RigidBody's and Colliders to the GameObjects (in this case a car) and then moving the cars by applying force or altering the velocity directly on the RigidBody tied to the GameObject. Give this video a watch, it explains the different ways to move GameObjects quite nicely:

 

I'm making a 2D top down game so I wont be using the Physics system at all. Its all turned off.

Thank you for the response but I actually found the answer I was looking for here, specifically the response from nickhoude21. https://forum.unity.com/threads/checking-if-a-specific-collider-is-colliding.396503/

By adding a polygon collider to the back and sides of the car I'm able to detect a collision from the the rear and sides of the vehicle allowing the second car to put its "brakes" on without the first one also doing the same.

 

Are you saying that if I translate the transform of a gameobject (object has colliders but no rigidbody2D) using FixedUpdate, Unity is recreating the colliders every frame, wasting resources?

 

Thank you for this video! I will look more into using velocity to move these cars around.

 

Cancel that velocity comment, MovePosition seems more appropriate with what I'm trying to accomplish.

 

Thank you for the clarity. I've watched the video NeilB133 posted and I would like to hear your thoughts on the pros and cons of using velocity vs movePosition.

 

So I have switched my game to use physics and for the most part everything already in place still works. New problem with adding rigidbodies is the cars no longer wait in line if traffic builds up and just start pushing each other around.

I tried freezing the X and Y positions on collision which stops them pushing but I cannot unfreeze them using onCollisionExit as the collisions never exit.

Thoughts on how I can prevent these instantiated prefab clones from pushing each other, stop movement when they collide, then resume movement once the player has moved out of the way from the first car?

 

Nevermind I figured it out myself

What a nightmare converting from transform.translate to using rigidbody and physics and it took all morning but I did it. Thanks.