I am trying to build a 2D space shooter game where the player will remain constant at the bottom of the screen and will move left and right. When the player fires a bullet(projectile), the bullet is going up just fine, but it is coming back again. Also if two bullets collide, they react to the collision.
I have two questions here:
How can I ensure that the bullet does not come back? (One way is to destroy it after a few seconds, but not sure if this is the right way)
How do I avoid collision between the bullets.
Here is my code snippet:
void Update () {
if (Input.GetButtonDown("Fire1"))
{
Rigidbody2D clone = (Rigidbody2D)Instantiate(bullet, transform.position + transform.up, transform.rotation);
clone.velocity = transform.TransformDirection(Vector3.up * 20);
}
}
I am very new to Unity and somehow wrote this code by looking into Unity Forums.Any help will be very much appreciated.
Thanks
More details:
I have created the bullet and added Rigidbody2D and a BoxCollider2D for this object. Made the bullet object a prefab and I dragged it under the Player object. Now bullet is a child of the Player object. Attached the script above to the Player object.
To answer your immediate questions:
1) I am not too sure about how you have the scene setup or about using the Unity 2D tools but usually if your bullets are coming back down then I would assume that you still have gravity applied to the rigidbody -- so make sure that you have that unchecked.
2) With Unity3D for objects to interact with each other they need rigidbodies attached. This is vital, say, if you want your lasers to destroy Monster #1. However, you only need one rigidbody attached to an object to have a desired effect. I would suggest removing the rigidbody from your laser and attach rigidbodies to objects ( Monster #1 ) that you want to be affected by the laser fire. ( That should work, if not there are other options -- one using layers and ignoring particular objects on those layers ).
Tips:
Here are some extra things. When you are creating objects and they fly off screen over time they will build up. Imagine you are in a large battle and you instantiated hundreds of lasers -- it will eventually be an issue for performance. So always consider Destroying objects after a certain amount of time.
Also, after looking at your code, I can't tell whether the velocity of the object is based upon its current position and nothing is being added. What I think is happening is when you instantiate an object it may be moving up, but because there is no incrementer, the object ( as it gets higher ) slows until it is at a rate which it is falling. For example this
clone.velocity = transform.TransformDirection(Vector3.up * 20);
should probably do this:
clone.velocity += transform.TransformDirection(Vector3.up * 20);
Heres http://docs.unity3d.com/Documentation/ScriptReference/Vector3-up.html, to read up on velocity. The problem is is that you need to continuously apply a constant forward motion so things in motion will tend to stay in motion. If not gravity will pull it down.
Also, heres a bit of code that I've used in the past that's created a pretty cool shooting laser effect thing:
public class Laser : MonoBehaviour {
public int fireRate = 70;
void Start(){
InvokeRepeating("FireLaser", 0.01f, 0.009f);
Destroy( gameObject, 2.0f );
}
void FireLaser(){
transform.Translate( Vector3.up * fireRate * Time.deltaTime );
}
}
edit: it's 3 a.m. and I hate proofreading.
Related
I made the endless movement of the object and its repulsion from the walls, but it does not always work correctly. At rounded corners (sometimes even at a straight wall), it just gets stuck and stops moving altogether, or moves slowly to the point where it stops moving. What can this be related to and how can it be fixed?
private void FixedUpdate() {
rb.velocity = direction * normalSpeed;
lastDirection = direction;
}
private void OnCollisionEnter2D(Collision2D collision) {
//Repulsion from objects.
direction = Vector3.Reflect(lastDirection.normalized, collision.GetContact(0).normal);
}
There is a small distance between the objects, but the circle seems to stick to the wall and moves with it until it collides with another collider:
Example
there are objects under the circle that also have colliders, but the collision between them is not considered, since they have the same layer (in the settings, I disabled the collision for objects on the same layer). What can be done to fix this error and what can it be related to?
The object in the general scale:
Example
I tried to increase the size of the wall collider, tried to change polygon collider to box collider, connect composite collider, changed the mechanics of the object movement (in these cases, the movement could work incorrectly), but the result was always the same - the jams (sticking to the wall) continued.
It is difficult to answer your question without having more information, but I can suggest if you are using physics to move your objects - utilize physic materials and remove code that changes direction manually in OnCollisionEnter. Using physic materials you can easily make your object bounce from colliders of your choice without losing velocity.
According to this article is possible to solve collision problems with fast moving objects in unity.
If you have particle system firing 1 sphere particle (ball throw for example) with collider and gravity modifier. And another moving collider with rigidbody (baseball bat for example), is there any possibility to make these object to NOT going through when they will collide in "high speed"? You cannot set "collision detection" on particle.
For better understainding I am adding two screenshots bellow.
Feel free for asking any question.
Collider(wall) is not moving, particle will bounce
Collider(wall) is moving towards ball with speed of "swing", particle goes through
The problem is because your objects are moving at a speed that they go through the collider. Say your object would move 10 units a frame, and it was 1 unit away from the collider. If the collider was 5 units long, it wouldn’t stop the moving object. This is because the next update will push it too far ahead of the next object.
First, don’t use a particle system for this. Just use a Rigidbody, because it is easier to handle in these situations.
You could solve this by doing a sweep test. A sweep test checks for colliders, where the object is going. You could just stop it from moving at the point it hit.
Rigidbody rb;
void Start()
{
rb = GetComponent<Rigidbody>();
}
void Update()
{
Sweep();
}
void Sweep()
{
RaycastHit hit;
if (Physics.SweepTest(rb.velocity, out hit, rb.velocity.magnitude))
{
rb.velocity = rb.velocity.normalized * hit.distance;
}
}
Make sure this script is on your ‘baseball’, and add force somewhere in this script. Make sure that you are not using particle system, but you are using Rigidbody.
This was untested; let me know if it doesn’t work or you get an error.
I have a problem with physics. It is my first time doing in 3D, so it may be just a beginner mistake.
I just wanted to create a simple player controller and make it so that it can not pass trough cubes.
The problem is that when going straight into the cube, part of the player is in the cube itself. When stop moving, it pushes me, so they are not intersecting (that makes sense).
I tried moving the player using .Transalte, .MovePosition and by changing the velocity of rigidbody itself. None of it change anything. The player can always move a part of him into the cube.
Any ideas how to solve this?
My player controller:
(The 2 lines commented out in Move() are just other ways to move the player.)
using UnityEngine;
public class PlayerController : MonoBehaviour
{
[SerializeField]
private float movementSpeed;
private Vector3 input;
private void Update()
{
GetInput();
}
private void FixedUpdate()
{
Move();
}
private void GetInput()
{
float inputHorizontal = Input.GetAxisRaw("Horizontal");
float intputVertical = Input.GetAxisRaw("Vertical");
input = Vector3.ClampMagnitude(new Vector3(inputHorizontal, 0, intputVertical), 1);
}
private void Move()
{
GetComponent<Rigidbody>().velocity += input * movementSpeed;
//GetComponent<Rigidbody>().MovePosition(GetComponent<Rigidbody>().position + input * movementSpeed * Time.deltaTime);
//transform.Translate(input * movementSpeed * Time.deltaTime, Space.World);
}
}
Player is standing still
Player is moving towards cube
Settings of the Game Objects itself
Now I think I understand your problem.
The collider is a geometric shape that is checked but the outcome wont take place until the collision has actually taken place, this means, one geometric shape being inside the other. By this I mean, that what you are experiencing is the normal behaviour of the collision. If both elemnts are rigid bodies, both will move and your problem wont be perceivable, but if your cube is not a rigid body or is kinematic, will stand still in the same position, and depending on the other object speed, its normal that an invasion/superposition of the elements is perceivable, because that is the frame were the collision took place, and were your element needs to be moved back because it has collided.
Consider that if the speed is high enough, and the position from one frame to another varies enough, the collision might not even take place, because the geometric parts do not interfere between frames, as the position variation might be bigger than the bounds of the collider itself. The collision check at the end of the day, is dicrete, and not continuous (even you can set it as continuous to be as frecuent as possible).
To solve or improve that, you can adjust the speeds to avoid that being perceivable + adjust your collider to make it react before the graphic superposition occurs. This means making the capsule or the cube collider bigger than the graphic element itself. You can even calculate , to make it as bigger as much as your your speed * Time.deltaTime result or speed * FixedTimeStep result, depending on your safety distance needs. I think one of those should be the safety distance you need to take into account before the graphic collision occurs.
Another thing you can do is tight more the times physics calculations are done.
https://docs.unity3d.com/Manual/class-TimeManager.html
But need to be careful with this as this can be a performance devourer and need to be handled with care. You can make some trials with that and check your problem can improve.
Hope that helps
You can increase the scale of your player's collider from the Collider component attached to it. You can check how big the collider is from the editor scene view.
Edit: The issue might be that your movement or collision code is called in Update instead of FixedUpdate. When working with rigidbodies, you want to call the physics calculations inside FixedUpdate.
remove rigidbody from the cube, you can click on 'Gizmos' in the top right of the editor and make sure the colliders are at the edges of the objects.
I need to move some transforms with attached colliders to a specific position, then check if one of them is hit by raycast.
I've done that the naive way (pseudo code) :
foreach(object in objects){
actual_position = object.transform.position
object.transform.position = object.new_position
}
if(Physics.Raycast(...)) objectHit();
// Then I revert each of them them back to their actual_position
After testing multiple times with the same context (same positions between tests for each objects), the raycast sometimes miss, sometimes not (~50/50).
Done a bit of research and found that in the Raycast doc page :
If you move colliders from scripting or by animation, there needs to
be at least one FixedUpdate executed so that the physics library can
update its data structures, before a Raycast will hit the collider at
it's new position.
So I calmed my anger and started looking for a solution.
This thread has a way using a coroutine to wait the next tick :
Raycast doesn't work properly
I'm affraid it won't work for me, as I need the objects to get back to their real position instantly.
This process can happen multiple times per frame (each time a player fire his weapon)
Is there a way to force the colliders update ?
If not... should I make my own raycasts and colliders ? :(
Thanks
Another workaround is to deactivate and activate Gameobject (attached collider) immediately. In this case collider position will be updated in single frame.
Another solution is
Physics.autoSyncTransforms and Physics.SyncTransform
Maybe you can try this out (adding to your pseudo-code):
foreach(object in objects)
{
actual_position = object.transform.position;
object.transform.position = object.new_position;
StartCoroutine(CheckToRevertOnNextFixedUpdate(object, actual_position));
}
IEnumerator CheckToRevertOnNextFixedUpdate(object, actual_position)
{
yield return new WaitForFixedUpdate();
if(Physics.Raycast(...)) objectHit();
// Then I revert each of them them back to their actual_position
}
Essentially this delays your check to the next FixedUpdate() for each object - and reverts each of them if needed. I hope this is not overcomplicated, since you only add a few lines of code.
I'm also assuming that moving the object's position for 1 FixedUpdate() frame would not have a visual effect of the the object teleporting to the new position and back. However, you can always move the collider only, and then move the rest of the transform there after the FixedUpdate().
Performance-wise, the best method seems to be updating the RigidBody.position:
private Rigidbody Rigidbody;
void Start()
{
Rigidbody = gameObject.GetComponent<Rigidbody>();
}
void Upate()
{
//.... your code
Rigidbody.position = newPosition;
}
Much faster then deactivate/activate or Physics.SyncTransform().
I'm new to Unity and after watching and reading some tutorials I'm now trying to make a simple 2D platformer kind of game. In the said game both enemies and player can jump to different platforms and traverse it like the old SnowBros game.
The problem I'm facing is related to programming the enemy movement. In my game there would be several types of enemies but generally for now there are two types, one that can jump from the platform and one that only walks upto the length of the platform, wait for 1 second then flip and walk backwards; meaning they don't get off the platform. Now this is an issue I'm having trouble with. I can't seem to find a way to calculate the length of the underlying current platform. I thought of using the collider.bound.min.x and max.x to come around the problem but the issue is I can't seem to find a simple way to reach the current platform's collider without fetching the script and then going through it.
Since, there would be many platforms of many different sizes and each platform is made up of a prefab of other platforms, it just doesn't seem like a workable solution to use the platform script and then traverse through it.
You can use Physics2D.Raycast to "sense" for collisions on a Ray. Imagine the enemy putting their toe one step forward, feeling if there is still solid ground, and then deciding whether to stop.
void Update()
{
Vector2 newPosition = transform.position + velocity * Time.deltaTime;
Vector2 downwardDirection = Vector2.down; // you may have to replace this with your downward direction if you have a different one
RaycastHit2D hit = Physics2D.Raycast(newPosition, downwardDirection);
if (hit.collider != null)
{
// solid ground detected
transform.position = newPosition;
}
else
{
// no ground detected. Do something else...
}
}
You can and should define the Layers your Raycast is supposed to hit, so it can ignore the enemy itself and avoid self-collision.
Well, I hope that you have prefabs of platform and in those prefabs put colliders at start and at end. You can specify layers and tags so that only enemy can detect those colliders and then you can detect tags on collision from enemy script and make your operation.
First create layers by opening Edit -> Project Settings -> Tags and Layers. Create two Layers
Create layers for enemy and enemyColliders and Goto Edit -> Project Settings -> Physics2D. Set collision matrix as EnemyCollider will collider with enemy only.
And your prefab will be looks like,
I hope this would help you.