Develop Reference

Sphere Collider, not pushing things when size is changed

So I'm trying to make a little pushback effect in my tests arena, I've got a sphere collider and here is my script:
// PushBack Class Script
if (Input.GetKeyDown(KeyCode.Q))
{
explosion_ball.transform.position = transform.position;
StartCoroutine(WaitAndPrint());
}
IEnumerator WaitAndPrint()
{
float i = 0;
while (i < 1)
{
i += 0.01f;
explosion_ball.radius = curve.Evaluate(i) * 10;
yield return new WaitForSeconds(0.01f);
}
}
//__________//
Sphere collider is set and stuff, but it doesn't push things back like I thought it would.
Thanks!
Edit:
explosion_ball is a sphere collider, I'm changing it with the point on the animation curve and * it by 10

EDIT:Unity Rigid bodies go to sleep so[Also Change interpolation to continuous if collider changes size too quickly]
A.check if obstacle rigid bodies are Sleeping with onTriggerEnter and Wake Up
void OnTriggerEnter(collider){ if(rb.IsSleeping()){rb.WakeUp();}
or
B.Attach this forceWakeUp Script to all Objects you want to be obstacles.
using UnityEngine;
public class forceWakeUp : MonoBehaviour
{
private Rigidbody rb;
void Start()
{
rb = gameObject.GetComponent<Rigidbody>();
}
void Update()
{
if(rb.IsSleeping()){rb.WakeUp();}
}
}
Forcibly Keeping Many objects awake Will impact performance.So ,your decision.
You need to scale up the collider on the object by radius and all the objects it is supposed to wobble need to have Rigid body component attached to them
2.if you ARE doing above things and its not adding any force you could just add a force on all the overlapping objects using the "OnCollisionEnterTrigger" and AddForceMethod radially away from the Sphere
Obstacle.position - Sphere.position is the vector Radially away from Sphere I think.
You don't need coroutines for this I think.

While searching through the Unity scripting API, found a method in there called
Rigidbody.AddExplosionForce(explosionForce, explosionPosition, explosionRadius, upwardsModifier, mode)
In order to get the rigid bodies that are to be affected by the explosion I would need to get them using Physics.OverlapSphere(position, radius) this gets all of the objects within the radius variable, then get the component.
Combining these two would also look like:
Collider[] colliders = Physics.OverlapSphere(transform.position, radius);
foreach (Collider hit in colliders)
{
if (hit.transform.tag == "Interactable")
{
if (hit.gameObject != hitgameObject)
{
Rigidbody rb = hit.GetComponent<Rigidbody>();
if (rb != null)
rb.AddExplosionForce(power, transform.position, radius, upForce, ForceMode.Impulse);
}
}
}
If there is any explaining that you would like me to do about my variables mentioned I will reply :)
Thanks for the help guys.

I don't know your curve and what values that evaluation produces, but you can check your code visually with Window/Analysis/Physics Debugger, or write a gizmo:
private void OnDrawGizmos()
{
Gizmos.color = new(1.0f, 0.0f, 0.0f, 0.5f);
Gizmos.DrawSphere(explosion_ball.transform.position, explosion_ball.radius);
}
Or simply just use https://docs.unity3d.com/ScriptReference/Rigidbody.AddExplosionForce.html

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);

How do I make my player with a Rigidbody move with isKinematic checked?

My game is a topdown zombie shooter and whenever the zombies get to the player they bunch up underneath them, to the point where the player can just walk over the zombies. I noticed that when I check isKinematic on the Rigidbody the zombies cant push the player up to go underneath him, so they just run into him(which is what I want). Despite this I am then unable to move. How can i fix this?
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlayerMoving1 : MonoBehaviour {
public float moveSpeed;
private Rigidbody myRigidbody;
private Vector3 moveInput;
private Vector3 moveVelocity;
private Camera mainCamera;
public GunController theGun;
void Start () {
myRigidbody = GetComponent <Rigidbody>();
mainCamera = FindObjectOfType<Camera>();
}
// Update is called once per frame
void Update () {
moveInput = new Vector3(Input.GetAxisRaw("Horizontal"), 0f, Input.GetAxisRaw("Vertical"));
moveVelocity = moveInput * moveSpeed;
Ray cameraRay = mainCamera.ScreenPointToRay(Input.mousePosition);
Plane groundPlane = new Plane(Vector3.up, Vector3.zero);
float rayLength;
if(groundPlane.Raycast(cameraRay,out rayLength))
{
Vector3 pointToLook = cameraRay.GetPoint(rayLength);
transform.LookAt(new Vector3(pointToLook.x,transform.position.y,pointToLook.z));
}
if (Input.GetMouseButtonDown(0))
theGun.isFiring = true;
if (Input.GetMouseButtonUp(0))
theGun.isFiring = false;
}
void FixedUpdate(){
myRigidbody.velocity = moveVelocity;
}
}

With isKinematic == true You can't change object position through rigidbody, You can only change transform.position.
I think it could be better, if You set isKinematic to false and add stopping distance to enemies, so they can't get too close to player.

Being that your player can no longer be effected by the physics engine, you'd have to manipulate the object's transform manually. Your script isn't ideally setup for it currently, but if I was to hack it into it and try to make it work it would look something like this:
(you can change it from fixedUpdate to update if you're no longer utilizing the physics engine)
void update(){
float x = Input.GetAxisRaw("Horizontal")* Time.Deltatime;
float z = Input.GetAxisRaw("Vertical") * Time.Deltatime;
transform.position = new Vector3(transform.position.x+x,0,transform.position.z+z);

Another way of doing this is to lock the position of Y for the player (assuming Y is the positive "up" direction). isKinimatic is best when you want to move the player or objects around yourself.
I would say upping the mass is better in this case, and you can keep isKinematic unchecked in this case then too. Also apply the lock for Y movement (again if it is the "up" direction from the plane)
Let me know what your solution is regardless, I've had some issues in the past as well with these types of events happening

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).