Ricochets dоn't wоrk prоperly - c#

Hi I want to make ricochet for my bullet. But when my bullet collides with a wall, bullet starts to fly along wall:
What did I do wrong? Here are my code parts:
public Rigidbody2D rb;
Vector2 m_dir;
private void Start()
{
m_dir = rb.GetRelativeVector(Vector2.right);
rb.velocity = m_dir * speed;
}
void OnCollisionEnter2D(Collision2D col)
{
if (col.gameObject.tag == "Wall")
{
Vector2 _wallNormal = col.contacts[0].normal;
m_dir = Vector2.Reflect(rb.velocity, _wallNormal).normalized;
Debug.Log("Collide!"); // debug works
rb.velocity = m_dir * speed;
}
}
Bullet Inspector - CircleCollider2D + Rigidbody2D. Wall Inspector - BoxCollider2D + Rigidbody 2D (Kinematic)

First of all:
The default behavior in Unity physics should already ricochet the bullet from the wall without your help.
As the bullet collider is round, it should not fly in a random direction.
What causes your problem:
The problem you have, seems to come from the order in which the methods are called.
Basically unity physics first resolves the collisions for this physics frame, and afterwards calls all the OnCollisionEnter methods. (More information)
This causes your rb.velocity to already be the ricochet velocity.
When you now calculate the reflect angle with the velocity pointing away from the wall, you get an inward pointing velocity.
In essence, your bullet keeps on ricocheting from the wall, but you change direction back to the wall in every frame.
How to solve it:
Use the Collision2d.relativeVelocity instead of rb.velocity.
This is the velocity that was recordet at the time of impact instead of the changed one.
Note: As it is relative to an unmoving object, you get the absolute velocity.
m_dir = Vector2.Reflect(rb.velocity, _wallNormal).normalized;
becomes
m_dir = Vector2.Reflect(-col.relativeVelocity, _wallNormal).normalized;

Related

Conflicting IF statements in Unity C# , Soccer Game

I am a starter in Unity and developing a soccer game. I have a problem ,my IF statements conflict each other. Let me explain it in detail.
In order for a ball to stick to player, I have used IF operator, so whenever the distance between the player and the ball is less than < 0.5 , the ball sticks to player and move together with it. Now when I try to set up shooting the ball (I try with "addforce") it doesnt let me, cause the ball is still attached to player and distance is <0.5.
This one is the balls script.
public bool sticktoplayer;
public transform player;
//gameobject Player is attached
float distancetoplayer;
Rigidbody rb;
//balls rigidbody
void Awake ()
{
rb = getComponent<Rigidbody>();
}
void Update()
{
If (!sticktoplayer)
{
float distancetoplayer = Vector3.Distance (player.position, transform.position);
if(distancetoplayer < 0.5f)
{
sticktoplayer = true;
}
}
else
{
transform.position = player.position;
}
if(Input.GetKeyDown(KeyCode.Space))
{
rb.addforce(20, 0, 0, ForceMode.Impulse);
sticktoplayer = false;
}
When the player is not controlling the ball the force is succesfully applied to the ball, but when the ball is attached (distancetoplayer<0.5) then the other IF statements blocks it from shooting.
Maybe there are some work arounds ? Thanks.
I tried to make another if statement.
why dont you try sticking the ball to the player by collision? instead of checking the distance, create a collider with the radius or scale you desire and whenever the ball is inside the collider (when it triggers with the collider) stick it to the player. Because you will not be able to let the ball go since the ball will always be less then 0.5f away from the player once it sticks
have you tried it this way?
if(Input.GetKeyDown(KeyCode.Space))
{
sticktoplayer = false;
rb.addforce(20, 0, 0, ForceMode.Impulse);
}

How to move a RigidBody2D to a position while still checking for collision

I am currently creating a game in Unity, in which you move a ball around using OnMouseDrag(), a CircleCollider2D and a RigidBody2D. This is how I set the position of the ball:
private void OnMouseDrag()
{
Vector2 mouseInWorld = Camera.main.ScreenToWorldPoint(Input.mousePosition);
playerRb.position = new Vector3(mouseInWorld.x, mouseInWorld.y, 0);
}
I still want the ball to slide on collision while the mouse moves around. Is there a way to do this?
I have tried RigidBody2D.MovePosition(), but the ball jumped around from one point to another, and Raycasts but couldn't get that to work either.
EDIT:
This is what I've got now:
playerRb.velocity = new Vector3(mouseInWorld.x - playerRb.position.x, mouseInWorld.y - playerRb.position.y, 0);
Now the problem is, that the ball lags behind the mousePosition.
When you use RigidBody.MovePosition, you don't call the physics engine and so it ignores collisions. If you want collisions to happen you need to use RigidBody.Velocity instead.
Doing this change will require you to make some change to your code though because what you give to RigidBody.Velocity is a velocity and not a position so you will need to calculate the velocity required in x,y (and z if you are in 3d) to reach your destination.
I invite you to read the Unity page about velocity for more info
https://docs.unity3d.com/ScriptReference/Rigidbody-velocity.html
Note: This will make the player/ball stick to collisions.
Modifying the velocity could cause the ball to bounce around unexpectedly when the ball collides with the wall. I would use a CircleCast for this, check if it hit anything, then use MovePosition accordingly:
float cursorDepth;
Rigidbody2D playerRb;
CircleCollider cc;
void Awake()
{
playerRb = GetComponent<Rigidbody2D>();
cc = GetComponent<CircleCollider>();
}
private void OnMouseDrag()
{
Vector2 mouseInWorld = Camera.main.ScreenToWorldPoint(Input.mousePosition);
Vector2 posToMouse = mouseInWorld - playerRb.position;
RaycastHit2D hit = Physics2D.CircleCast(playerRb.position,
cc.radius * transform.lossyScale.x, posToMouse, posToMouse.magnitude);
if (hit.collider != null)
{
mouseInWorld = hit.centroid;
}
playerRb.MovePosition(mouseInWorld);
}
But notice that if the ball can't move all the way to the mouse, it might cause the drag to end. So, plan accordingly.

How to check how hard an object hits the ground and create an explosive "force" around it

Recently I have started my first 2D game project on unity and everything has been going well. My only problem so far is with my enemy. My enemy, when attacking, jumps in the air and then falls and hits the ground. I want my script to detect when it falls and how hard it falls then create a force that pushes the player back as if its an "explosion."
So my questions are how do I detect the enemy hitting the ground, after a fall, and then add a force?
I tried using onCollisionEnter2D on Unity but it does not work since technically even when the enemy is moving it's still "falling."
Here is my attempt at checking if the enemy fell then searching for the player and calling the explosion force function.
private void OnCollisionEnter2D(Collision2D collision)
{
if(collision.gameObject.tag == "Ground")
{
foreach (Collider2D Obj in Physics2D.OverlapCircleAll(transform.position, radius))
{
if (Obj.GetComponent<Rigidbody2D>() != null && Obj.gameObject != gameObject)
{
Debug.Log("Calling Function");
Rigidbody2D rb = Obj.GetComponent<Rigidbody2D>();
ExplosionForce2D forceScript = GetComponent<ExplosionForce2D>();
forceScript.AddExplosionForce(rb, force, transform.position, radius);
}
}
}
}
This is my code for adding a force to the object.
public void AddExplosionForce (Rigidbody2D body, float expForce, Vector3 expPosition, float expRadius)
{
var dir = (body.transform.position - expPosition);
float calc = 1 - (dir.magnitude / expRadius);
if (calc <= 0) {
calc = 0;
}
body.AddForce (dir.normalized * expForce * calc);
}
I expect that, if the player is in the enemy radius, and the enemy jumps, falls, and hits the floor it will push the player back as if it was an explosion.
you can use a flag that can check that if the enemy is falling or not, so when your enemy is actually falling set this as true, if not (means moving) then set as false.
Checking for Velocity is a good solution.
So you can do like,
body.velocity.magnitude
// magnitude to remove the direction issue.
// now apply all this as
body.AddForce(dir.normalized * expForce * calc * body.velocity.magnitude);

2D Polygon Collider not causing collisions with a 2d polygon collider

I am in the middle of working on a game, and I just started. I added in the map as a png and have been adding in colliders around the areas that I want to be impassable (it is a 2D platformer). I have an enemy already designed and added a 2DRigidBody component to it as it moves around, and started to use 2DBoxColliders as the colliders for the level, and my script that I have written:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Sexapus : MonoBehaviour {
public static int Velocity = 42;
public Rigidbody2D rb;
public Vector2 dir;
public Animator anim;
void Start () {
rb = GetComponent<Rigidbody2D>();
dir = new Vector2(1, 0);
anim = GetComponent<Animator>();
}
// Update is called once per frame
void Update () {
rb.velocity = dir * Velocity;
anim.SetFloat ("Direction", dir.x);
}
void OnCollisionEnter2D (Collision2D col) {
dir = dir * -1;
}
//CHECK TASKS
}
Meant that the enemy would hit the side of a wall and then rotate and start going the other way. I realised with the size of my map that using multiple 2DBoxColliders (and when I say multiple I mean I would probably have to use over a hundred) was a very bad way of doing it. I have now started to use a 2DpolygonCollider for the map as well, but now the enemy doesn't collide with the sides of the wall and turn around, it just stays facing the same direction but doesn't move. Anyone know why?
You are using the same collider for the floor and the walls... So when you collide with the wall, and are already touching the floor, the OnCollisionEnter will not happen.
So, you do get the collision, hence the object cant move past the wall, BUT it's not a new collision!
Solution: Use a collider to the floor, and a different one to the walls, Edge colliders are good for this.

Player stops moving upon contact with a gameObject

I am having my player constantly drop downwards on the screen and when the player interact with other gameobjects, I want to destroy those gameobjects and want the player to carry on dropping.
But the moment the player hits the other gameobject, the gameobject does gets destroyed but the player stops dropping. Please help advice what I am doing wrong.
//Script attached to player:
//x-axis movement speed
public float playerMoveSpeed = 0.2f;
//how much force to act against the gravity
public float upForce = 9.0f;
//horizontal control
private float move;
// Update is called once per frame
void Update()
{
//player left right x-axis movement control
move = Input.GetAxis("Horizontal") * playerMoveSpeed;
transform.Translate(move, 0, 0);
}
void FixedUpdate()
{
//to fight against the gravity pull, slow it down
rigidbody.AddForce(Vector3.up * upForce);
}
//Script attached to gameObject to be destroyed on contact with player
void OnCollisionEnter(Collision col)
{
//as long as collide with player, kill object
if (col.gameObject.tag == "Player")
{
Destroy(gameObject);
}
}
First one should solve your problem, the second one might make your life easier :)
1.) Mark the objects as "Triggers" so that no real collision happens. That way your player should just fall through and keep its speed. You also need to use OnTriggerEnter instead of OnCollisionEnter
2.) If you dont really need "forces" but just want to move the player constantly you could just turn off gravity and set rigidbody.velocity manually like(i am assuming 2d here):
void FixedUpdate()
{
horizontalVelocity = Input.GetAxis("Horizontal") * playerMoveSpeed;
rigidbody.velocity = new Vector3(horizontalVelocity, verticalVelocity, 0.0f);
}
Just play around with values for verticalVelocity and horizontalVelocity untill it feels right.
Also note that if you move something in Update() you should probably multiply the translation with Time.deltaTime or your player will move faster on higher fps. FixedUpdate is called in fixed time intervalls so you dont need it there(thats why its called Fixed Update).

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