Why my character didn't move with this code? - c#

I sticked my character to an empty object and applied Rigidbody, script to that empty object(To change the pivot); nevertheless, the character is not moving with this code:
public class main_character : MonoBehaviour
{
public float speed;
private float max_vel = 4f;
private bool grounded = true;
private bool flip = true;
private Rigidbody2D main_vel;
private void Awake()
{
main_vel = GetComponent<Rigidbody2D>();
}
void FixedUpdate()
{
float now_vel = Mathf.Abs(main_vel.velocity.x);
if (Input.GetKey("d") && flip)
{
flip_side();
if (now_vel < max_vel)
{
main_vel.AddForce(new Vector2(speed, 0f) * Time.deltaTime);
}
}
if(Input.GetKey("a") && !flip)
{
!flip_side();
if (now_vel < max_vel)
{
main_vel.AddForce(new Vector2(-speed, 0f) * Time.deltaTime);
}
}
}
void flip_side()
{
flip = !flip;
transform.Rotate(0f, 180f, 0f);
}
}

you either need to add a speed value to the top of the class, or dynamically generate it. I would also put an exception or debug that catches when you press the button while speed is set to zero.
if speed accelerates you're going to need to build it or call it in update and give it an initial speed + speed based on delta time. I would also clamp it to max speed there instead, as it prevents large values being tracked by the game engine.
--Regarding an empty parent situation, If there is no physics components, the child should retain the motion of it's parent. That being said, you must have a rigidbody to add force to. You look like you might be using 2d so I have less experience with those rigidbodies, but I imagine it would have to not be kinematic to accept force as you are doing. After checking for that, I would maybe add some debug that posts your vector2 and speed from inside your max_vel check.

Related

Floating when adding Time.deltaTime to movement

My movement is working fine without Time.deltaTime but when I add it to my player movement I can move left to right fine but I fall slowly and I cant jump
using Newtonsoft.Json.Bson;
using System;
using UnityEngine;
using UnityEngine.SceneManagement;
public class PlayerMovement : MonoBehaviour
{
[SerializeField] private float horSpeed;
[SerializeField] private float vertSpeed;
private Rigidbody2D rb;
private Boolean isJumping;
private void Start()
{
rb = GetComponent<Rigidbody2D>();
}
private void Update()
{
// we store the initial velocity, which is a struct.
var v = rb.velocity * Time.deltaTime;
if (Input.GetKey(KeyCode.Space) && !isJumping)
{
vf.y = vertSpeed;
isJumping = true;
}
if (Input.GetKey(KeyCode.A))
{
vf.x = -horSpeed;
}
if (Input.GetKey(KeyCode.D))
{
vf.x = horSpeed;
}
if (Input.GetKey(KeyCode.S))
{
vf.y = -vertSpeed;
}
rb.velocity = vf;
if(Input.GetKey(KeyCode.Escape))
SceneManager.LoadScene(0);
}
private void OnCollisionEnter2D(Collision2D collision)
{
isJumping = false;
}
}
I've added it to my enemy script and it works fine so im not sure whats different with player movement to using transform.position
Why would you multiply the velocity by Time.deltaTime?
This is used to convert a value from a "certain unit per frame" into a value "certain unit per second".
A velocity already IS a value in units per second.
Linear velocity of the Rigidbody in units per second.
=> It makes no sense to apply Time.deltaTime here at all.
For your X axis movement it doesn't make much difference since you anyway apply that velocity continuously every frame. Here you just would probably want to handle the case where neither left nor right is pressed and set vf.x = 0.
For the Y axis however you apply the jump only once, just to divide it by about 60 (or whatever your frame rate is) right in the next frame => you never give it the chance to fall or jump.
In general you should modify the Rigidbody in FixedUpdate. In your specific case it is fine to do this in Update, it is just redundant work ;)

Why my float variable always at 0 even i set it

I just start making a game with Unity and Visual Studio, i have a bit confuse that why my Speed value always at zero even i set it equal to another variable.
public class Ballista : MonoBehaviour
{
public Transform firePoint;
public GameObject arrowPrefab;
public float speed = 10f;
public float startTimeHold;
public float holdDownTime;
public float arrowSpeed = 100f;
public float finalSpeed;
private void Update()
{
if (Input.GetKeyDown(KeyCode.M))
{
startTimeHold = Time.time;
}
if (Input.GetKeyUp(KeyCode.M))
{
holdDownTime = Time.time - startTimeHold;
Shoot();
finalSpeed = holdDownTime * arrowSpeed;
}
Debug.Log("holddowntimeis: " + holdDownTime);
Debug.Log("final speed is: " + finalSpeed);
}
public void Shoot()
{
GameObject arrowGO = (GameObject)Instantiate(arrowPrefab, firePoint.position, firePoint.rotation);
}
}
and this is the script that my speed value always zero
{
Rigidbody2D rgBody2D;
public GameObject ballista;
private float speed;
private void Awake()
{
rgBody2D = GetComponent<Rigidbody2D>();
}
private void Start()
{
\\ i though the code below will set my speed equal to my finalSpeed but it still 0
speed = ballista.GetComponent<Ballista>().finalSpeed;
Vector2 mousePos = Input.mousePosition;
Debug.Log("speed: " + speed);
rgBody2D.AddForce(mousePos * speed * Time.deltaTime);
}
void Update()
{
}
}
Different to what others said here you actually do NOT want to do it in Update.
Your goal here is to once give your newly spawned arrow a start velocity, not a continuous force.
The issue here is of other nature I think:
You are always spawning a new instance of your second script from a given prefab. This prefab seems to hold a reference to a Ballista prefab instance. At least you are never assigning a new value to the ballista! It might simply be a wrong reference where the finalSpeed is never updated.
Your are first doing the Shoot and after it set the finalSpeed -> even if it would be the correct reference you always get the wrong finalSpeed value!
I would actually change your two scripts in order toake your arrow instance being controlled by the Ballista instead of letting each spawned arrow poll the speed itself:
public class Ballista : MonoBehaviour
{
public Transform firePoint;
// By giving it the correct type here you don't need GetComponent later
public Rigidbody2D arrowPrefab;
public float startTimeHold;
public float arrowSpeed = 100f;
// I personally would add aax value and clamp since to fast RigidBodies can break collision detection eventually
public float maxArrowSpeed = 300;
private void Update()
{
if (Input.GetKeyDown(KeyCode.M))
{
startTimeHold = Time.time;
}
if (Input.GetKeyUp(KeyCode.M))
{
var holdDownTime = Time.time - startTimeHold;
// get the speed before you shoot
// Here personally I would clamp to be sure the arrow is never faster than maxArrowSpeed
// regardless of how long the user held the button pressed
var finalSpeed = Mathf.Min(holdDownTime * arrowSpeed, maxArrowSpeed);
Debug.Log("holddowntimeis: " + holdDownTime);
Debug.Log("final speed is: " + finalSpeed);
// pass in your speed
Shoot(finalSpeed);
}
}
private void Shoot(float speed)
{
// Instantiate anyway returns the type of the given prefab
// which now is a Rigidbody2D
var arrow = Instantiate(arrowPrefab, firePoint.position, firePoint.rotation);
// Directly set the speed from here
// -> your arrow doesn't even need an extra component
// Since you already spawned it with the correct rotation you maybe don't even need the mouse position thing
// AddForceRelative adds a force in the local space of the arrow so if the rotation is correctly
// this simply adds the force in its forward direction
// Note that also using Time.deltaTime actually only makes sense if you set something continuously
// For a one-time force you wouldn't need it, rather adjust your arrowSpeed field
arrow.AddForceRelative(Vector2.forward * speed);
}
}
Instead of using AddForce or AddForceRelative you could actually also simply set the target velocity:
arrow.velocity = Vector2.forward * speed;
Since you are not updateding it continuously this is totally fine and a lot easier to foresee the actual target speed since when adding a force you have to take the mass and frictions into account. You would than ofcourse have to adjust the arrowSpeed (and evtl maxArrowSpeed) accordingly to not anymore represent a force but an actual velocity in Units/second.
I hope I made my points clear enough, don't hesitate to ask if something stayed unclear ;)
speed = ballista.GetComponent().finalSpeed;
should Come in
void Update(){
}
block and not in
void Start() {
}
as void start is only run once and at that point in time the speed is zero
Hope it helped :)
Start happens only once.
Start is called on the frame when a script is enabled just before any
of the Update methods are called the first time.
Disregarding everything else, i am guessing you want it to update the speed every frame in Update
Update is called every frame, if the MonoBehaviour is enabled.
private void Update()
{
\\ i though the code below will set my speed equal to my finalSpeed but it still 0
speed = ballista.GetComponent<Ballista>().finalSpeed;
Vector2 mousePos = Input.mousePosition;
Debug.Log("speed: " + speed);
rgBody2D.AddForce(mousePos * speed * Time.deltaTime);
}

OnCollisionStay not working in 2D movement script

So, I'm still not the best at this but I'm trying to use this script for 2D movement but the jumping isn't working for some reason. It keeps saying that the OnCollisionEnter function "is declared but never used". Can someone tell me what im doing wrong? Thanks
If I remove the (Collision col) part it says that "void cannot be used in this context".
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class RonyWalking : MonoBehaviour
{
Rigidbody2D rigid;
SpriteRenderer sprite;
public bool isJumping;
public float spd = 2.0f;
// Start is called before the first frame update
void Start()
{
rigid = GetComponent<Rigidbody2D>();
sprite = GetComponent<SpriteRenderer>();
}
// Update is called once per frame
void Update()
{
if(Input.GetKey("d")){rigid.velocity = new Vector2(spd, 0);}
else if(Input.GetKey("a")){rigid.velocity = new Vector2(-spd, 0);}
if(Input.GetKeyDown("w") && isJumping == false)
{
rigid.velocity = new Vector2(0, 5);
isJumping = true;
}
void OnCollisionStay(Collision col)
{
isJumping = false;
}
}
}
When using 2D physics, you need to use the 2D lifecycle methods;
void OnCollisionStay2D(Collision2D col)
{
isJumping = false;
}
And you shouldn't put this method inside your Update method... It should be on class level:
public class RonyWalking
{
void Update()
{
// ...
}
void OnCollisionStay2D(Collision2D col)
{
// ...
}
}
Don't worry about "Is declared but never used", this may be because you don't have specific code referencing the method, but Unity will raise events that calls it, "automagically"
Another thing that I can see while reading your code, that may be unintentional behaviour for you, is that when clicking left/right, you set velocity UP to 0, and when clicking up you set LEFT/RIGHT velocity to 0; this will result in freezing the movement mid-air if you jump, then move while in air:
Click D; velocity = 2, 0
Click W; velocity = 0, 5
Character will now move upwards until another input is given
Click D; velocity = 2, 0 and the character will continue moving while in air because when moving sideways the up/down velocity is set to 0
To solve this, either set the other to existing velocity or make the inputs manipulate a Vector that you then apply at the end of the movement code:
Vector2 existingMovement = rigid.velocity;
if (Input.GetKey(KeyCode.D))
existningMovement.x = spd;
else if (Input.GetKey(KeyCode.A))
existningMovement.x = -spd;
if (Input.GeyKeyDown(KeyCode.W) && !isJumping)
{
existningMovement.y = 5f;
isJumping = true;
}
Furthermore, I think you may have some unexpected behaviour with OnCollisionStay; it will fire every frame that you're colliding with the ground, I assume. But I think it may also fire a frame or two AFTER you've jumped since the physics of your character will not INSTANTLY leave the collision, so isJumping will be set to false even after your jump, letting you jump while in the air one more time.
I would recommend that you use OnCollisionExit2D(Collision2D col) to set isJumping = true instead, or OnCollisionEnter2D(Collision2D col) and set it to isJumping = false, depending on the functionality you desire (if you want the ability to jump after walking out of a cliff)

Unity- Player Jump Height / Public, Private, Static, nothing

I have been following a tutorial on 2D Player Controller in Unity (It's 'Live Training 16 Dec 2013 - 2D Character Controllers' video).
I was able to implement everything the tutorial showed successfully with some edits to make it work in Unity 5. Afterwards, I decided to play around with it so that I can gain a better understanding. One thing I tried to do was changing the jump height when pressing the Space key. Here is the code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class RobotControllerScript : MonoBehaviour {
public float maxSpeed = 10f;
bool facingRight = true;
Animator anim;
bool grounded = false;
public Transform groundCheck;
float groundRadius = 0.2f;
public LayerMask whatIsGround;
public float jumpForce = 700f;
// Use this for initialization
void Start () {
anim = GetComponent<Animator>();
}
// Update is called once per frame
void FixedUpdate () {
grounded = Physics2D.OverlapCircle(groundCheck.position, groundRadius, whatIsGround);
anim.SetBool("Ground", grounded);
//vSpeed = vertical speed
anim.SetFloat("vSpeed", GetComponent<Rigidbody2D>().velocity.y);
float move = Input.GetAxis("Horizontal");
anim.SetFloat("Speed", Mathf.Abs(move));
GetComponent<Rigidbody2D>().velocity = new Vector2(move * maxSpeed,
GetComponent<Rigidbody2D>().velocity.y);
if (move > 0 && !facingRight)
{
Flip();
}
else if (move < 0 && facingRight)
{
Flip();
}
}
void Update()
{
if(grounded && Input.GetKeyDown(KeyCode.Space))
{
anim.SetBool("Ground", false);
GetComponent<Rigidbody2D>().AddForce(new Vector2(0, jumpForce));
}
}
void Flip()
{
facingRight = !facingRight;
Vector3 theScale = transform.localScale;
theScale.x *= -1;
transform.localScale = theScale;
}
}
Looking at the code and the tutorial explanations, jumpForce is the variable that controls how high the character will jump (force applied). So, I changed 700f to a 5f. I expected the character to make a really small jump, but this was not the case. It jumped at the same height as 700f.
public float jumpForce = 700f;
After playing around with the code, I was able to have the expected result by removing the 'public' next to jumpForce. Other ways to fix this was setting it to private or static. I remember I had a similar problem when making a temperature widget on QT Creator. I had to set a variable to static or else it would not return to the default value after C to F conversion, but I don't remember exactly why.
Can anyone explain why 'public' does not work and why a private/static/nothing might? What is the best/efficient solution for this problem? Thank you very much.
When a field is public (or serializable), it is shown in inspector. When it is shown in inspector, you tweak it's value, a you expect the tweaks you make to the value, in the inspector, to be preserved between play mode runs.
When you declare a variable in the code, you may specify an initial value, like this:
public float jumpForce = 700f;
So, the first time this object gets inspected, after created, it has a reasonable value. Then, you tweak and choose a better value (or back to the same, whatever). That's the value you preferred! You want the object to keep functioning like this while you go ahead and finish making your game.
So, once a field is tweaked in Inspector, it doesn't respect the initial value you hardcoded anymore, and that's usually what everyone want. Imagine how annoying would be if everytime you make a change in your class, all the tweaked fields got back to the initial hardcoded value...
If a field was previously public, and then you make it private (or hidden in inspector by any mean), then the hardcoded initial value will stand.
But, what if I really want my object to get back to it's initial/default configuration? That's why the Reset method and the reset button in inspector were made!

Update breaks function in Unity

I have the following code
public Rigidbody2D rb;
public float speed = 5f;
void FixedUpdate()
{
if (Input.GetKeyDown("w"))
{
Fire();
}
}
void Fire()
{
rb.MovePosition(rb.position + Vector2.down * speed * Time.deltaTime);
}
but every time I play the game, the ball does not move according to the fire function, it only goes down by 1 on the y-axis.
How can I edit my code, so that the Rigidbody moves according to the Fire() function?
There could be a couple things going wrong here. The first thing that stands out to me is that you're using Input.GetKeyDown instead of Input.GetKey-- GetKeyDown only returns true on the first frame that the key is pressed (so it's useful for things like shooting once per keypress), whereas GetKey returns true for the entire time that the key is down (so it's useful for things like movement). Changing that should give you the behavior that you're expecting.
Another issue is that you're doing input checking in FixedUpdate. It runs on a separate game loop from Update, and you can find more details about that here: Is it really wrong to use Input.GetKey() on FixedUpdate?
I would use Input and GetKey to store the input state in a Vector2 in the Update loop, and then use that data in FixedUpdate to do the actual movement:
public Rigidbody2D rb;
public float speed = 5f;
private Vector2 velocity = Vector2.zero;
void Update()
{
if (Input.GetKey("w"))
{
velocity = Vector2.down * speed;
}
else {
velocity = Vector2.zero;
}
}
void FixedUpdate()
{
MoveBall();
}
void MoveBall()
{
rb.MovePosition(rb.position * velocity * Time.deltaTime);
}
This way, you also have a stronger separation between the input code and movement code, and it will be easier to handle once you start trying to implement more complexity. Good luck!

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