In Unity 2D, how do I achieve Non-trigger collsion that doesn't "physically" move the rigidbodies? - unity3d

I have a bullet game object and an enemy game object.
I want to have the ability of getting the collision point/contact, which's why I think I need the collider of the bullet to not be a trigger collider - this way, I want to have the bullet bounce off the enemy. At times, the bullet will need to bounce off of rectangular objects (not a problem), but I also want the bullet to bounce off of elliptic objects (the problem).
I want the bullet not to "physically" push the enemy, which is why, intuitively, I should set the bullet's collider to be a trigger collider.
When the bullet's collider is a trigger collider, I seemingly don't have a way to implement the bouncing.
But when the collider's not a trigger collider, it pushes the enemy object.
There's no code errors, but I think the code hasn't got anything to do with the problem.
I suspect the problem may have something to do with the Physics Collision Matrix.
EDIT
It seems that raycasting would be the solution to the problem, as Leoverload proposed. My problem became a different problem now, so I'll close off this thread, and open a new one.
Thanks for the help, #Leoverload ! :D

For the position of the hit it's very easy. You must have 2 colliders and 2 Rigidbody and then you can simply add a
Void OnTriggerEnter2D(Collision Coll) and inside it check for the tag : if(coll.compareTag("surface")) and inside you can get the position with collision.transform.position.
The collision matrix on the Physics menu only allows to remove Collision between certain layers, it's useful if you want the enemies not to push eachother!
If you don't want the player pushed you can change the collider to trigger, and destroy the bullet just after the collision with the same method as before with a void OnTriggerEnter2D and the compareTag. In this way it will look like it touches the enemy and explode, but it won't actually touch anything. If you want to add knockback to the player then you could do a simple AddForce based on the direction of the bullet and the work is done!
If you want to avoid the bullet to move walls you can set walls to static and it should work fine

Related

The problem with the correct use of a rigid body in a 2D game

I decided to make a 2D game for the PC on Unity, where the character moves around the stage. But I have a problem with the correct use of Rigid Body 2D.
In this picture you can see my playing field.
https://i.stack.imgur.com/PBhwx.png
I want my character to move around the entire field and when colliding with objects does not go through them.
My field is Tilemap, but I hung the Box Collider on the Grid. Boxing collider surrounds the grid.
But when I use Rigid Body and turn on the game, the object falls through. And if you remove the Rigid Body, then it just goes through objects.
I tried to use different types of Rigid Body, when using kinematic and static, sprite goes through houses.
The way it works is when you attach a RigidBody2D to an object, you give it physics properties, but it won't do anything useful without a collider. If you have an object with collider attached - every other object with collider attached will collide with it.
In your case the player should have RigidBody2D and BoxCollider2D. The ground should have BoxCollider2D, and basically everything you want the player to collide with should have BoxCollider2D. So the houses should have BoxCollider2D as well.
This setup should allow the player to walk on the ground without falling through it, and collider with houses.
Make sure that the collider's area is correct. You can preview it in the editor and edit it if it's not correct.
Also if you want it to work make sure the camera points down and your game setup is alongside Y axis so if there's a rigid body object falling down it falls down on the ground not before/behind it.

Unity Making a prefab collide with surroundings, but not other objects of the same prefab

The picture below is my simulation, and the problem im facing is that they wont collide they way i want to.
I made them move randomly and i want this behavior.
The green balls are supposed to "bounce" off the outer grey walls, so collide with them (simulate physics)
The green balls are NOT supposed to bounce of each other, but only do triggerevents (so i know when they are on top of each other)
How do i do this. I have looked at multiple tutorials and i simply dont know what to do. As far as i understand, to make a collision, one of the objects has to have a rigidbody on, and the other a normal collider?
I have to tried to follow this overview. The balls are from the same prefab, so to get a trigger for them i have to pick either
static trigger collider, rigidbody collider trigger, or kinematic rigidbody trigger collider (as seem from the overview).
BUT if i pick any of those i cant get a collision with the walls? Do i have to do the wall collisions myself?
What you can do is make all the walls static colliders, and make a script on all the balls that check whether they hit a wall or a ball. and do actions that way.
Or
Make the walls check for a collision with the ball and add a force to the negative direction that they came from or something.(up to you how you want the balls to behave)
for example :
OnTriggerEnter(collision other)
if(other.transform.tag == Ball)
//Run Some Code here
// for example
BallRb other.GetComponent<RigidBody>();
BalRb.addForce //add the force that you want.

Do I need a rigidbody for gameobject that scales up and down?

I have a beginner-like question. I currently have a gameobject in my scene that scales up and down via animation. It has a Circle Collider 2D on it.
I've seen some tutorials before regarding the performance optimizations of rigidbodies and colliders. I learned that if the gameobject should move in the game, it should have a rigidbody component. Otherwise, a collider component itself is fine for triggers.
Since my game object is kind of moving (because of the endless scale up/down animation), would it be best to put a rigidbody component on it?
I do like to mention that I'm not using any physics movement such as AddForce or anything like that. Hope someone can clear this up.
A gameobject should have a rigidbody component for mainly two reasons, first one is if you are using physics, second one is if you want other colliders to detect a hit/entrance/exit by that gameobject.
From what you described it does not seem like you would need a rigibody on your gameobject, especialy because the movement is only by scale and not by position.
and also, just to clarify, putting a rigidbody component on a gameobject is not a must even if the gameobject is moving. there are different ways to move objects, and rigidbody usually helps in case that the movement should be very realistic and interact with other gameobjects it is colliding with.

Raytracing not responding correctly

So I'm new to Unity and I'm sure I'm missing an easy step, but after looking online for a while for some reason I can't find the solution.
I have two objects on the screen, player and enemy. Both have Rigidbody2D, and Box Collider 2D attached. On Box Collider 2D I have clicked is triggered On Rigidbody2D for both I have clicked Is Kinematic. On player I have a simple movement script. On the enemy object I have this:
void Update () {
RaycastHit2D hit = Physics2D.Raycast(transform.localPosition,transform.right,Mathf.Infinity);
Debug.DrawRay(transform.localPosition,transform.right);
if (hit)
Debug.Log(hit.collider);
}
Now for some reason when I move player over the object if (hit)
is true, but if I move the player anywhere on the right side it is not true. What would be the reason for this? Thanks.
First of all you don't need Rigidbody for raycast detection, only colliders. Second, Physics2D.Raycast uses world position, not local, so replace "transform.localPosition" with "transform.position", this messes it up a lot if the transform is child of something. Take in mind that you are sending raycast from the right side of your transform, so maybe it's not hitting anything and values you are getting are actually correct.

Collision detection, without the physics?

I have enemies following a path in my game. Along the path I have turrets shooting at them. To get collision detection between the bullet of the turret and enemy i've added RigidBody2D, and Circle Collider 2D to the enemy, and Circle Collider 2D to the bullet.
When the bullet hits the enemy it shall not push the object, just destroy the bullet and take some of the health.
I feel Rigidbody2D is messing it up, it gives mass, drag and gravity to my enemy... but I dont need it. But it seems I do if I want to have collision detection bewteen two objects?
You need Rigidbody to detect collisions, however you are just triggering some actions (taking damage). That is why you can check isTrigger on your colliders, and then implement 'OnTriggerEnter2D' callback instead of 'OnCollisionEnter2D', which won't activate any physics.
See http://docs.unity3d.com/Documentation/ScriptReference/Collider2D.OnTriggerEnter2D.html for reference.