I have rigidbody2D on arrow and enemy. both are at 0 z coordinates. I don't want to use colliders as I want the enemies to be able to stack on top of each other. When I turn colliders on, the code works and the objects get destroyed. Is there another function I could use that works with rigidbodies only? I thought OnCollicionEnter worked with rigidbodies.
arrow
function OnCollisionEnter2D(coll: Collision2D) {
Debug.Log("I hit something");
coll.gameObject.SendMessage("ApplyDamage", 10);
Destroy (gameObject);
}
enemy
var health = 20;
function ApplyDamage (damage : float)
{
health -= damage;
if ( health <= 0)
{
Destroy(gameObject);
}
}
Collisions require one Rigidbody to happen. In your OnCollisionEnter you could check if the coll parameter has a rigidbody attached. And only then apply the damage.
I just added a box collider to the enemy and set rigidbody2D to "is kinematic." This allowed the enemies to group up on top of each other while I could still collide. Also used OnTriggerEnter2D(coll: Collider2D) instead of OnCollisionEnter2D(coll: Collision2D).
Related
I have a Gameobject called ball and another called floor. As can be seen in the code, when the ball hits the floor, a printout shall be made.
void OnCollisionEnter2D(Collision2D collision)
{
bg = GameObject.Find(bg_name);
if (collision.gameObject.tag == "floor")
{
//bg.GetComponent<ControlGame>().deleteBall();
//bg.GetComponent<ControlGame>().recreateBall();
print("Ball hit floor");
}
if (collision.gameObject.tag == "rope")
{
bg.GetComponent<ControlGame>().ToggleIsShot(false);
}
}
The problem is that I have moved the floor now, such that the ball and the floor has different depth. Still, the printout is made although the two Gameobjects are not touching. See the screenshots below:
The print is in the lower left corner. Why is that?
According to the comment below, the z-value does not have an effect. But I have also a collision detector for the rope, which is a Bezier-curve with an EdgeCollider2D attached to it. When the rope passes the floor, nothing is triggered in onCollisionEnter2D.
void OnCollisionEnter2D(Collision2D collision)
{
bg = GameObject.Find(bg_name);
if (collision.gameObject.tag == "floor")
{
print("floor collision");
bg.GetComponent<ControlGame>().ShootBall();
}
}
Well, these are Collider2D.
You only changed the Z (depth) position of the floor which basically is completely ignored in a 2D game / by 2D physics.
As you can also see in the GameView for the Physics 2D the objects are still aligned and colliding.
Why isn't it also working for collision between rope and floor?
Please checkout the Collision Action Matrix for which collisions/trigger can be detected.
→ At least one of the objects has to be a Rigidbody2D.
If the rope is e.g. moved by script then it has to be a Kinematic → in this case also the floor would need to be a Rigidbody2D and not Kinematic.
The reason I guess it worked just fine for the ball is because it already is a non-kinematic Rigidbody2D so able to detect collisions with static colliders.
So, as the title implies, my OnCollisionEnter is not being called. I'm not sure why. The objects are bouncing off surfaces they contact.
Here's the relevant code:
static Rigidbody m_ProjectileRigidbody;
internal void FireProjectile(GameObject projectile, float speed)
{
projectile.transform.position =
State.PlayerTransform.position + State.PlayerTransform.forward;
projectile.transform.rotation = State.PlayerTransform.rotation;
m_ProjectileRigidbody = projectile.GetComponent<Rigidbody>();
m_ProjectileRigidbody.AddForce
(State.PlayerTransform.forward * speed, ForceMode.Impulse);
if (State.PlayerState.Consumes)
{
State.PlayerState.ConsumeCellEnergy(EnergyConsumption);
State.PlayerState.GenerateCellHeat(HeatProduction);
}
}
void OnCollisionEnter(Collision collision)
{
Debug.Log("Collided With: " + collision.gameObject.name);
}
If you are working with 2D colliders and rigidbodies, use OnCollisionEnter2D instead of OnCollisionEnter.
And make sure in Edit -> Project Settings -> Physics the collision matrix is properly set.
And also, double check that:
Both objects have collider, rigidbody properly set up.
Both objects are active.
You do not accidentally disable collider, rigidbody or set
isKinematic, isTrigger from your script.
How do I prevent a collision from applying forces in Unity? I am using 2D physics and want an arrow to stick into a crate. I can easily remove the rigid body and collider in the collision callback, but it seems that a frame of collision force is still applied to the arrow, causing slight jumps in position and rotation. Settings isKinematic on the rigid bodies in the collision callback also appears to not prevent this one frame of force being applied.
I am hoping to tell Unity to not apply physics for the collision.
Using kinematic for the life time of the arrow is not an option because the arrow needs to fly realistically until it hits something.
Here is the code for the crate object that handles the collision:
protected virtual void HandleCollision(ArrowScript arrow, Collision2D coll)
{
StickArrow(arrow, coll);
if (DestroyAfterSeconds >= 0.0f)
{
Destroy(arrow.gameObject, DestroyAfterSeconds);
}
}
private void OnCollisionEnter2D(Collision2D coll)
{
ArrowScript script = coll.gameObject.GetComponent<ArrowScript>();
if (script != null)
{
HandleCollision(script, coll);
}
}
private bool StickArrow(ArrowScript arrow, Collision2D coll)
{
Vector2 surfaceNormal = coll.contacts[0].normal;
float surfaceAngle = Mathf.Atan2(surfaceNormal.y, surfaceNormal.x);
float arrowAngle = Mathf.PI + (arrow.transform.eulerAngles.z * Mathf.Deg2Rad);
float angleDifference = Mathf.Abs(BowAndArrowUtilities.DifferenceBetweenAngles(surfaceAngle, arrowAngle));
float penetration = arrow.PercentPenetration * PenetrationPercentageModifier * (1.0f - angleDifference);
if (penetration <= MinimumPenetrationPercentage)
{
arrow.PercentPenetration = 0.0f;
return false;
}
// Make the arrow a child of the thing it's stuck to
arrow.transform.parent = transform;
arrow.gameObject.transform.Translate(new Vector3(-penetration * arrow.Length, 0.0f, 0.0f));
SpriteRenderer thisSpriteRenderer = GetComponent<SpriteRenderer>();
if (thisSpriteRenderer != null)
{
arrow.GetComponent<SpriteRenderer>().sortingLayerID = thisSpriteRenderer.sortingLayerID;
arrow.GetComponent<SpriteRenderer>().sortingOrder = Mathf.Max(0, thisSpriteRenderer.sortingOrder - 1);
}
BowAndArrowUtilities.PlayRandomSound(arrow.CollisionAudioClips, penetration * 5.0f);
// destroy physics objects from the arrow (rigid bodies, colliders, etc.). This unfortunately doesn't prevent this frame from apply force (rotation, position) to the arrow.
arrow.DestroyPhysicsObjects();
return true;
}
Unity version is 5.3.4.
I ended up making the arrow head a trigger. Inside of OnTriggerEnter2D, I then perform a circle cast in the direction the arrow is pointing with a width of the arrow head sprite. Triggers do not get affected by Unity physics calculations.
private void OnTriggerEnter2D(Collider2D coll)
{
ArrowScript script = coll.gameObject.GetComponent<ArrowScript>();
if (script != null)
{
Vector2 dir = -script.ArrowHead.transform.right;
// ray cast with the arrow size y value (thickness of arrow)
RaycastHit2D[] hits = Physics2D.CircleCastAll(script.ArrowHead.transform.position, script.Size.y, dir);
foreach (RaycastHit2D hit in hits)
{
// collider2d is a member variable assigned in Start that is the Collider2D for this object
if (hit.collider == collider2d)
{
HandleCollision(script, hit.normal);
break;
}
}
}
}
Your problem is that OnCollisionEnter and OnTriggerEnter are called after all the collisions are resolved.
The simplest way to solve this without affecting anything would be to change the weight of the box, arrow, or both.
Set the weight of the crate to a high value, and the weight of the arrow to a low value.
Another way is to use trigger colliders, as you have done. However trigger colliders have problematic side-effects. For example, it doesn't call OnCollisionEnter or OnTriggerEnter on the crate. You will have to do all the logic inside the arrow script, which is not much of a problem.
There are a lot of other ugly hacks however. You could set the velocity of the box to 0 after impact, but it would freeze the crate if you hit it as it was moving. You could use the collision information to cancel the force applied to the crate to solve the collision. You could save the last velocity of the crate every frame, and reapply it to the rigid body during the OnCollision call.
I wouldn't suggest any of these, but they are possible.
I am have some difficulty with what is probably a very silly thing. I have an enemy gameobject that depending on where it is hit (collision) - either it, or the play dies. I think the simplest way to describe this is by using the classic Super Mario Bros. game as an example.
As you all know, if the player runs into the enemy - the player will lose - UNLESS he jumps on top of the enemy's head, in which case the enemy should die.
My initial idea was to create two colliders on the gameobject:
Blue border represents a BoxCollider2D - that if collided with - will cause player to lose (notice it is slightly lower from the top)
Green border represents a BoxCollider2D on a child gameobject - that if collided with - will cause the gameobject to die.
The following is a simplified version of the code I used:
// Collider #1
public void OnCollisionEnter2D(Collision2D collision)
{
// Trigger 'Game-Over' logic
}
// Collider #2
public void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.tag == "Player")
{
Destroy(this.gameObject);
}
}
This kind-of works, however momentarily after colliding with Collider #1, Collider #2 is also trigger - and while the enemy is destroyed, the player also loses.
I have been playing with the RigidBody2D values to prevent the player from entering the 2nd collider when hitting the enemy from the top - but apparently with that force / speed, the colliders may be slightly inaccurate (or maybe I'm just doing it wrong?).
I have looked into RayCasts but this seems too complex for something that me appears rather trivial (casting rays on all four sides and four vertices of the player - assuming that the player has a box collider).
What I have resorted to 'for the moment' is a a single collider with a simple piece of code that I am unhappy with, and doesn't always work:
public void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.tag == "Player")
{
float yVelocity = collision.gameObject.transform.rigidbody2D.velocity.y;
if (yVelocity < 0)
{
Debug.Log("Enemy will lose..." + yVelocity);
Destroy(this.gameObject);
}
else
{
// Trigger 'Game-Over' logic
}
}
}
I'm currently working in 2D mode, but solutions for 3D mode (while maybe more complicated than necessary for my question) will also be considered.
Thanks guys.
as a game developer you always have many ways to solve a problem or make a gameplay.
first of all i have to say you should make a polygon collider 2d fo you objects and chracters. just colliding pictures is not very good as i see you used box cilliders in your game.
a good choice can be that you attach and empty object ot you player and set its position under foots of you player and check of enemy hit that enemy dies else if enemy hit main character object, player dies.
another choice can be when o objects collide check y position of 2 objects. of player was higher he kiils, else enemy kills the player.
if you think more you will find more answers.
you have to examin diffrent ways and find most efficient.
I think it will be easy to disable the other collider when one is triggered. You can easily enable/disable colliders with collider.enabled = true; or collider.enabled = false;
// Collider #1
public void OnCollisionEnter2D(Collision2D collision)
{
// Trigger 'Game-Over' logic
// collider2.enabled = false;
}
// Collider #2
public void OnCollisionEnter2D(Collision2D collision)
{
// collider1.enabled = false;
if (collision.gameObject.tag == "Player")
{
Destroy(this.gameObject);
}
}
This way it will be pretty lightweight and easy to implement.
One way of implementing what you want is to put each collider in its child own game object and use the IsTouching() method.
void OnTriggerEnter2D(Collider2D other){
if(GameObject.Find("Top Trigger").GetComponent<BoxCollider2D>().IsTouching(other)){
Destroy(transform.gameObject)
}
if(GameObject.Find("Bottom Trigger").GetComponent<BoxCollider2D>().IsTouching(other)){
Destroy(other.gameObject)
}
}
I have a raycast, however it goes through the enemies as it is suppose to but it hits nothing else. If I remove the mask it hits the enemies layer. If I remove the layer and use raycastall it hits only the enemies.
If I use raycast it goes clear through a wall and hits the player but does not show as a hit, in fact i get the error
NullReferenceException: Object reference not set to an instance of an object
EnemyAI.OnTriggerEnter2D (UnityEngine.Collider2D other) (at Assets/Scripts/EnemyAI.cs:32)
Line 32 is Debug.Log (hit.transform.gameObject);. If I remove it, nothing happens at all. No error, and no hit.
Heres is the code
void OnTriggerEnter2D(Collider2D other){
if (other.gameObject.tag == "Player") {
myStats.inRange = true;
Vector2 direction = other.transform.position - transform.position;
hit = Physics2D.Raycast(transform.position, direction, myCircle.radius + 1, LayerMask.GetMask("enemies"));
Debug.Log("Radius size is " + (int)myCircle.radius);
Debug.Log("donthit value " + LayerMask.GetMask("Enemies"));
Debug.Log("direction " + (myStats.player.transform.position - transform.position));
Debug.DrawRay(transform.position, other.transform.position - transform.position, Color.white);
Debug.DrawLine(transform.position, myStats.player.transform.position, Color.white);
//Destroy(hit.transform.gameObject);
Debug.Log (hit.transform.gameObject);
if(hit != null && hit.transform.gameObject != null){
if (hit.transform.gameObject.tag == "INDESTRUCTIBLE") {
Debug.Log("WALL");
// Destroy the Tag "Enemy" here
}
if (hit.transform.gameObject.tag == "Player") {
Debug.Log("player");
// Destroy the Tag "Enemy" here
}
Debug.Log("Tag name is " + hit.collider.tag);
}
Debug.DrawRay(transform.position, myStats.player.transform.position - transform.position, Color.white);
}
}
So it seems there are two things at work here. First, according to the documentation, Raycast 2D will also detect collider(s) at the start of the ray. If you don't use raycastAll then the source enemy will stop your ray before it goes out into the world. To prevent this you could use a layer mask. Just to be sure, a layer mask signifies the layer that you want to hit, not the layers you want to ignore. So to make sure the enemy layer is the only layer you ignore you can use this:
var layerMask = Physics2D.DefaultRaycastLayers & ~LayerMask.GetMask("Enemies");
And then use this mask in your raycast.
Second, there must be a reason you're not hitting anything else. If you applied the layermask in the wrong way then you filter out any hits against the wall or player. It looks like you both have an enemy tag and an enemy layer so make sure to get this straight. But if you used raycastAll without mask and still didn't hit anything then make sure your objects meet all the requirements. They must have 2D colliders of course. If they have colliders, make sure they either aren't triggers or that "Raycasts hit Triggers" is enabled in Edit -> project settings -> physics2d.
A final thing to check is whether or not your ray goes far enough. I noticed your debug draw does not reflect your raycast perfectly. Use this to draw the actual ray:
Debug.DrawLine(transform.position, transform.position + direction * (myCircle.radius + 1) / direction.magnitude, Color.white);