Im currently developing an Air hockey game in Unity3d. The issue I'm having is that when the player attempts to hit the puck too quickly, the player ends up going through the puck and therefore there is no collision. The game works perfectly as expected if the player stays still and the puck hits the player or if the player hits the puck at a slow pace.
The player has a rigidbody using continuous collision detection using a capsule collider. The puck also has rigidbody with continuous dynamic collision detection and a mesh collider with convex.
I tried setting the fixed timestep to 0.01 but that didn't have an effect. Here is the script for the player movement:
void ObjectFollowCursor()
{
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
Vector3 point = ray.origin + (ray.direction * distance);
Vector3 temp = point;
temp.y = 0.2f; // limits player on y axis
cursorObject.position = temp;
}
and here is the code for the puck when it collides with the player:
// If puck hits player
if(collision.gameObject.tag == "Player")
{
Vector3 forceVec = this.GetComponent<Rigidbody>().velocity.normalized * hitForce;
rb.AddForce(forceVec, ForceMode.Impulse);
Debug.Log ("Player Hit");
}
Any help would be much appreciated. Thanks.
The problem you are having its called "tunneling".
This happens because your object is moving at a high speed and in that specific frame the collision is not detected. In frame n the ball is just in front of the bat, but when frame n+1 is calculated the ball has moved behind the bat, thus "missing" the collision completely.
It is a common problem but there are solutions.
I recommend you study this script and try to implement on your game.
This is not my code:
SOURCE: http://wiki.unity3d.com/index.php?title=DontGoThroughThings
using UnityEngine;
using System.Collections;
public class DontGoThroughThings : MonoBehaviour
{
// Careful when setting this to true - it might cause double
// events to be fired - but it won't pass through the trigger
public bool sendTriggerMessage = false;
public LayerMask layerMask = -1; //make sure we aren't in this layer
public float skinWidth = 0.1f; //probably doesn't need to be changed
private float minimumExtent;
private float partialExtent;
private float sqrMinimumExtent;
private Vector3 previousPosition;
private Rigidbody myRigidbody;
private Collider myCollider;
//initialize values
void Start()
{
myRigidbody = GetComponent<Rigidbody>();
myCollider = GetComponent<Collider>();
previousPosition = myRigidbody.position;
minimumExtent = Mathf.Min(Mathf.Min(myCollider.bounds.extents.x, myCollider.bounds.extents.y), myCollider.bounds.extents.z);
partialExtent = minimumExtent * (1.0f - skinWidth);
sqrMinimumExtent = minimumExtent * minimumExtent;
}
void FixedUpdate()
{
//have we moved more than our minimum extent?
Vector3 movementThisStep = myRigidbody.position - previousPosition;
float movementSqrMagnitude = movementThisStep.sqrMagnitude;
if (movementSqrMagnitude > sqrMinimumExtent)
{
float movementMagnitude = Mathf.Sqrt(movementSqrMagnitude);
RaycastHit hitInfo;
//check for obstructions we might have missed
if (Physics.Raycast(previousPosition, movementThisStep, out hitInfo, movementMagnitude, layerMask.value))
{
if (!hitInfo.collider)
return;
if (hitInfo.collider.isTrigger)
hitInfo.collider.SendMessage("OnTriggerEnter", myCollider);
if (!hitInfo.collider.isTrigger)
myRigidbody.position = hitInfo.point - (movementThisStep / movementMagnitude) * partialExtent;
}
}
previousPosition = myRigidbody.position;
}
}
You were right to try continuous collision detection (CCD). There are some constraints (especially in this case where you want to use CCD with two moving objects rather than one moving object and one static object), but it is designed for this kind of scenario. The Rigidbody documentation goes into these constraints:
Set the collision detection mode to Continuous to prevent the
rigidbody from passing through any static (ie, non-rigidbody)
MeshColliders. Set it to Continuous Dynamic to also prevent the
rigidbody from passing through any other supported rigidbodies with
collision detection mode set to Continuous or Continuous Dynamic.
Continuous collision detection is supported for Box-, Sphere- and
CapsuleColliders.
To sum up, both puck and paddle need to be set to Continuous Dynamic, and both need to be Box-, Sphere-, or Capsule Colliders. If you can make these constraints work for your game you should be able to get continuous collision detection without writing it yourself.
A note about Unity's CCD that bears repeating:
Note that continuous collision detection is intended as a safety net
to catch collisions in cases where objects would otherwise pass
through each other, but will not deliver physically accurate collision
results, so you might still consider decreasing the fixed Time step
value in the TimeManager inspector to make the simulation more
precise, if you run into problems with fast moving objects.
But since you are manually specifying the collision reaction, that might not be an issue.
Related
So I am making a small game in unity where you have to shoot the enemy. However, when I made the script for the bullet and enemy, it half worked and half didn't. Sometimes, the bullet would hit the enemy and destroy the enemy, however, sometimes, it would take multiple shots for it to work. But when I turn the speed of the bullet to 1 (the speed of the bullet was 500), the bullet always destroys the enemy. So this leads me to think that this has something to do with the speed of the bullet. Here is my script
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
}
private void OnTriggerEnter(Collider other)
{
Destroy(other.gameObject);
Destroy(gameObject);
Debug.Log("e");
}
For the movement of the bullet, I just used transform.Translate(Vector3.up * Time.deltaTime * speed). How can I fix this?
The problem is not that Destroy do not work with a certain speed, the problem is that with certain speed you are not triggering the "OnTriggerEnter".
This fenomenon is called "tunneling" it happens when the object goes too fast.
That provokes that in one frame the projectile is on one side of the collider, and in the next frame is on the other side of the collider, giving the sensation like a teleport, so that's the why it do not collide, cause in any frame the engine has detected the collide.
If you're having troubles with high speed stuff, try to set your rigidbody (the one that is moving) to Interpolate, or use raycasts to fake bigger projectile colliders.
In addition to Lotan's answer
I just used transform.Translate(Vector3.up * Time.deltaTime * speed)
whenever using physics you do NOT want to set anything via Transform as this bypasses the physics engine and thereby breaks collision detection etc as in your case.
You rather want to through the Rigidbody component and e.g. use Rigidbody.MovePosition
Rigidbody.MovePosition moves a Rigidbody and complies with the interpolation settings
like
private Rigidbody _rigidbody;
private void Awake()
{
_rigidbody = GetComponent<Rigidbody>();
}
private void FixedUpdate()
{
_rigidbody.MovePosition(_rigidbody.position + _rigidbody.rotation * Vector3.up * Time.deltaTime * speed);
}
or why not simply set it only once
private void Start()
{
GetComponent<Rigidbody>().velocity = transform.up * speed;
}
Additionally you want to set the interpolation to dynamic.
A tricky way : bullet form A point to B point by one frame , so you can fake a point on a to b like
fake point: A+B/2
Point a ;
Point b ;
Update()
{
Point ab = (a+b)/2;
bullet.point = ab;
//check collider some .
bullet.point = b; // set it back.
a = b;
}
Not a good solution . but it have double hit rate.
Preamble:
I have a 3D side scroller style game in which the player flies along avoiding stuff, you know, side-scrollery things.
I'd like to add an effect (particle system) to the player when they get close (within a preset dangerZone, say 1.6 units (meters)) to the terrain, like a dusty dragging cloud under them sort of thing. I'm familiar with the particle system and raycasts but I don't know how to marry the concepts together to achieve what I'm after. The terrain undulates randomly and is not a flat surface, if that helps.
I'd also be hoping to make the particle system 'grow' the closer the player gets to the terrain if that makes sense. There is also speed to consider, so the closer to the ground and faster the player is should have an effect on the particle system.
My Thoughts:
I already have a score multiplier that uses a raycast to check the player's position from the ground/terrain and increases the closer they get.
void Update() {
force = speed *2;
RaycastHit hit;
Ray downRay = new Ray(transform.position, -Vector3.up);
if (Physics.Raycast(downRay, out hit, dangerZone)) {
var distanceToGround = hit.distance;
float hazardMultiplier = Mathf.Round( (transform.position.y - distanceToGround)*100 ) /100;
if (hit.collider.tag == "Terrain") {
playerData.scoreMulitplier = hazardMultiplier;
}
}
else {
playerData.scoreMulitplier = playerData.baseScoreMulitplier;
}
}
I'm thinking I can use the raycast I already have to instantiate a particle system on the terrain/at the raycast hit point but I'm not sure how exactly to go about this.
Any help is appreciated and thanks in advance.
You're on the right track. A couple things first before we dive into the solution:
Raycasts are calculated on the fixed frame (physics, FixedUpdate), not the visual frame (Update). While you may invoke a Raycast during Update, it won't be calculated until the next FixedFrame anyways. I'd recommend moving this to FixedUpdate to reduce the chance of doubled logic (2 simultaneous raycasts) or skipped logic (no raycasts).
You can set your particle system's scaling mode to the hierarchy, and scale using the transform. Alternatively, you can set the startSize of the particleSystem's main attributes.. Since you want to change the size of the particleSystem to change fairly frequently, I would recommend changing the scaling mode to hierarchy and just modifying the transform of the object it is attached to.
[SerializeField]
ParticleSystem ps;
[SerializeField]
float dangerZone = 1.6f;
[SerializeField]
float maxParticleSize = 2.0f; //How much you want particles to scale up based on closeness to terrain
void FixedUpdate() {
RaycastHit hit;
Ray downRay = new Ray(transform.position, -Vector3.up);
//Consider adding a layerMask parameter here that only interacts with the "terrain" layer. This will save you physics computing power, and remove the need for tag checking every frame (which is not efficient).
if (Physics.Raycast(downRay, out hit, dangerZone)) {
var distanceToGround = hit.distance;
float hazardMultiplier = Mathf.Round( (transform.position.y - distanceToGround)*100 ) /100; //This doesn't make too much sense to me, so you may want to revisit this. Since this isn't scoped for this question we can ignore it.
//If you use a layerMask, then you wouldn't ever need to check
if (hit.collider.tag == "Terrain") {
playerData.scoreMulitplier = hazardMultiplier;
float particleScale = 1 + (dangerZone - hit.distance) / dangerZone;
ps.transform.localScale = (particleScale, particleScale, particleScale);
if(ps.isStopped)
ps.Play();
} else //In scenarios where the raycast hits a non-terrain target, you'll need to turn off particles. If you use a layermask this wouldn't be needed.
{
if(ps.isPlaying)
ps.Stop();
}
}
else {
if(ps.isPlaying)
ps.Stop();
playerData.scoreMulitplier = playerData.baseScoreMulitplier;
}
}
I am developing a VR game.
Is a fighting game, the player will be able the punch the enemies (on his fist will be a collider and a disabled object with the damage script).
I need a script that will activate another object (the one with damage script) - (placed on his fist) but just on certain speed or force (you know, like in real life- if the enemy will be touched with the hand he should not be damaged, just on high force or speed)
What is the best solution?
thank you!
Since your player's fist is not being controlled by the physics system, it will not be possible to read the velocity of the player's hand like you would a normal Rigidbody. That being said, you can still calculate the speed and handle all of what you wish to do in one script.
Here's an example:
[RequireComponent(typeof(DamageScript))]
public class HandSpeedMonitor : Monobehaviour
{
public float threshold;
DamageScript damageScript;
Vector3 lastPos;
public void Awake()
{
damageScript = this.GetComponent<DamageScript>();
}
public void Start()
{
lastPos = this.transform.position;
}
public void Update()
{
float velocity = (lastPos - this.transform.position).magnitude / Time.deltaTime;
if(!damageScript.enabled && velocity > threshold)
damageScript.enabled = true;
else if(damageScript.enabled)
damageScript.enabled = false;
}
}
However, since .magnitude is an expensive call, you may want to consider storing your "threshold" as a squared speed "sqrThreshold" and use .sqrMagnitude, since it removes the square root component of vector math (saving on processing).
The Issue
I'm making a 2D Unity game where the main weapon of your character is a fireball gun. The idea is that a fireball will shoot out of the player's hand at the same angle the player's hand is pointing. I have 3 issues:
When I shoot the fireball, since the fireball is a RididBody, it pushes the player. This is because I've made the centre of the player's arm (the same place where the fireball shoots from) the point at which the arm rotates around the player (what is meant to be the shoulder);
To instantiate the fireball prefab on the arm, the only way I know how to do it is by using a piece of code which requires the arm to be a RigidBody. This means that the arm is affected by gravity and falls off the player on start unless I freeze the arm's y-axis movement, which means that when the player jumps, while the arm does not fall, it floats at the same y-position as where it started while moving along the x-axis; and
When the fireball is shot, the angle from which it is propelled after being shot is not the same angle as the angle of the player's arm.
Instantiating the Fireball
if (Input.GetKeyDown(KeyCode.Space))
{
pew.Play();
var fireballTransform = Instantiate(fireballPrefab); //creates a new shot sprite
fireballTransform.position = new Vector3(transform.position.x + horizMultiplier, transform.position.y, transform.position.z);
fireballTransform.rotation = orientation;
fireballTransform.transform.Rotate(0, 0, transform.rotation.z);
}
if (Input.GetKeyDown(KeyCode.D)) // moves right
{
orientation = 0;
horizMultiplier = 0.08F;
}
if (Input.GetKeyDown(KeyCode.A)) // moves left
{
orientation = 180;
horizMultiplier = -0.08F;
}
This piece of code is located within the script applied to the player's arm. The movement of the arm works fine and the problem seems to be either within this piece of code or the code for my fireball (which I will put next). A few definitions:
pew is a sound effect played when the fireball is shot;
horizMultiplier is the distance from the arm's centre which I would like the fireball to instantiate (also dependant of if the player) is facing left or right); and
orientation is which direction the player is facing (left or right). The fireball is then instantiated facing that same direction.
Fireball Script
public Vector2 speed = new Vector2(); // x and y forces respectively
private Rigidbody2D rb; // shorthand
private float rotation;
void Start()
{
rb = GetComponent<Rigidbody2D>(); // shorthand
rotation = rb.rotation;
if (rotation == 0)
{
rb.AddForce(Vector3.right * speed.x); // propels right
}
if (rotation == 180)
{
rb.AddForce(Vector3.left * speed.x); // propels left
}
}
I believe this code is explanatory enough with comments (if not please comment and I'll address any question). I believe an issue could also be in this piece of code because of the lines: rb.AddForce(Vector3.right * speed.x); and rb.AddForce(Vector3.left * speed.x); as these add directional forces to the object. I don't know is this is objective direction (right or left no matter what direction the object the force is being applied to is facing) or if it's right or left in terms of the object-- say if an object was rotated 90 degrees clockwise and that object had a force applied so that it moves right making the object move downwards.
What I'm expecting to happen is the player's arm will turn so that when a fireball is fired it is fired in the direction the arm is facing. The arms turning mechanics are fine, it's just trying to properly instantiate the fireball. Can anyone help with any of the issues I've laid out?
How I would go about this:
Add an empty transform as child of the arm and move it to where the fireball should spawn. Also make sure the rotation of it is such that its forward vector (the local z-axis) points to where the fireball should go. To see this, you need to set "Local" left of the play button.
Spawn the fireball at the transform's position with its rotation.
Ignore collision between the arm's/player's collider and the fireball's collider with https://docs.unity3d.com/ScriptReference/Physics.IgnoreCollision.html. If necessary, you can enable the collision between the two colliders again after 1s or so.
Set the fireball rigidbody's velocity to speed * rigidbody.forward.
If you need help with the code, please post it so I can see what's going on.
Edit:
The arm definitely doesn't require a Rigidbody.
You can just use Instantiate(prefab, position, rotation) as shorthand.
Is this for a 2D game?
Also, I'm going to sleep now but I'll gladly try to help tomorrow.
Your Issues
1) You should be masking the fireball's layer not to collide with your player's layer.
You can find more info about this here: https://docs.unity3d.com/Manual/LayerBasedCollision.html
(note: make sure you're on the Physics2D panel, and not the Physics one, as that's for 3D)
2) There is a setting called gravityScale in RigidBody2D. You should set this to 0 if you don't want gravity to be affecting your object. More info: https://docs.unity3d.com/Manual/class-Rigidbody2D.html
Fireball Instantiate
if (Input.GetKeyDown(KeyCode.Space))
{
pew.Play();
var position = hand.transform.position + hand.transform.forward * horizMultiplier;
var rotation = hand.transform.rotation;
var fireball = Instantiate<Fireball>(fireballPrefab, position, rotation);
fireball.StartMoving();
}
Fireball Script
private Rigidbody2D rb; // shorthand
private float rotation;
public float Speed;
public void StartMoving()
{
rb = GetComponent<Rigidbody2D>(); // shorthand
rb.velocity = transform.forward * Speed;
}
void OnTriggerEnter(....) { .... }
I have a blockbreaker type game coded using C# that mainly works fine but upon play testing i have found the ball will slow right down in certain situations! i.e if it wedges between to game object bricks the force of the ball rapidly slows down! 8 times out of ten this will not happen but other times it does and im unsure why! i will post the Ball script i think you will need to help solve this but should you need anymore information then please ask.
public class Ball : MonoBehaviour {
private Paddle paddle;
private bool hasStarted = false;
private Vector3 paddleToBallVector;
void Start () {
paddle = GameObject.FindObjectOfType<Paddle> ();
paddleToBallVector = this.transform.position - paddle.transform.position;
}
// Update is called once per frame
void Update () {
if (!hasStarted) {
//lock ball relative to the paddle
this.transform.position = paddle.transform.position + paddleToBallVector;
//wait for mouse press to start
if (Input.GetMouseButtonDown (0)) {
//if (Input.GetTouch(0).phase == TouchPhase.Ended){
hasStarted = true;
this.GetComponent<Rigidbody2D> ().velocity = new Vector2 (2f, 10f);
}
}
}
void OnCollisionEnter2D(Collision2D collision){
Vector2 tweak = new Vector2 (Random.Range(0f,0.2f),Random.Range(0f,0.2f));
if (hasStarted) {
GetComponent<AudioSource> ().Play ();
GetComponent<Rigidbody2D>().velocity += tweak;
}
}
}
You are adding directly to the velocity of the ball. The velocity variable defines a direction and speed, not just a speed as you are thinking here.
So, when the ball collides with a block it has a velocity of (+x, +y). After the collision and bounce is has a velocity of (+x, -y). So by adding a random positive value to the velocity when it has the -y velocity means that it will slow down the ball.
This does not happen every time because you are moving the ball in your Update() method. Change that to 'FixedUpdated()'. Fixed Update handles all physics calculations.
Also, I would recommend having a RigidBody2D on your Ball object. Moving physics objects should always have RigidBodies. With this, you can then use AddForce in the forward direction of your ball and that should solve your problem.
EDIT: I see you have a RigidBody2D already. I missed that the first time. Instead of having GetComponent<RigidBody2D>().velocity try GetComponent<RigidBody2D>().AddForce( transform.forward * impulseAmount, ForceMode.Impluse );