Develop Reference

Update() interrupting itself

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class StatReader : MonoBehaviour
{
public float modifier;
bool isIncrease = false;
void Update()
{
CheckInput();
Reading();
}
void CheckInput()
{
if (Input.GetKeyDown(KeyCode.Mouse0))
{
Debug.Log("Input received.");
if (isIncrease == false)
{
Slider slider = gameObject.GetComponent<Slider>();
slider.value += modifier * Time.deltaTime;
isIncrease = true;
}
else
{
Slider slider = gameObject.GetComponent<Slider>();
slider.value -= modifier * Time.deltaTime;
isIncrease = false;
}
}
}
void Reading()
{
Slider slider = gameObject.GetComponent<Slider>();
float readingOutputs = slider.value;
if (readingOutputs <= 0f)
{
readingOutputs = 0f;
}
if (readingOutputs >= 100f)
{
readingOutputs = 100f;
}
Debug.Log(Mathf.RoundToInt(readingOutputs));
}
}
As you can see from my script above, I'm trying to achieve the following goals:
Once press left mouse button, the slider starts filling up until I click the button again.
Once click it again, the slider starts depleting until I click the button again.
The problem is:
When I click the left mouse button, the slider will fill up but only for a moment notice. So the value increases to 0.000438 or something. Then it stops automatically. When I click again, it goes back to zero. I've been debugging it by myself for quite some time now. It seems like Update() is interrupting itself. Every frame it stops to check the input, which is why the increase/decrease was such a small value.
I have another problem actually:
Initially, I used FixedUpdate() instead of Update(). Weirdly, when I hit play , the program cannot pick up every input when I'm spamming the left mouse button. The problem went away once I changed FixedUpdate() to Update(). The problem is solved but I want to know why it happened.
Please help! Thanks a lot in advance!

Update is called every frame. Your Update is not interrupted but rather only doing something when GetKeyDown returns true.
Well GetKeyDown is true only in one single frame when you started pressing the key.
And then you also immediately toggle between increasing and decreasing after adding the value once.
Anyway you should also avoid calling GetComponent in Update and rather store and re-use the reference
I would rather simply do something like
// already reference via the Inspector if possible
[SerializeField] private Slider _slider;
// a little helper method you can invoke via the context menu of your component
// allows you to a) already store the reference in the serialized field
// and b) you ca already see whether the reference is actually found as expected
[ContextMenu(nameof(FetchComponents))]
private void FetchComponents()
{
// as a FALLBACK get the reference ONCE
if(!_slider) _slider = GetComponent<Slider>();
}
private void Awake()
{
FetchComponents();
}
void CheckInput()
{
if (Input.GetKeyDown(KeyCode.Mouse0))
{
// simply invert the direction ONCE on key press
isIncrease = !isIncrease;
}
// increase or decrease depending on the current flag state EVERY FRAME
// Clamp your result value between 0 and 100
var newValue = Mathf.Clamp(_slider.value + modifier * Time.deltaTime * (isIncrease ? 1 : -1), 0f, 100f);
// apply the new value EVERY FRAME
// but only if it is actually different (-> hasn reached 0 or 100)
// to avoid unnecessary calls of onValueChanged
if(!Mathf.Approximately(_slider.value, newValue))
{
slider.value = newValue;
}
}
Your other issue about FixedUpdate: This is the physics routine (and should only be used for physics related things usually). It is called on a fixed time base (by default usually every 0.02 seconds) => It is clear that some of your single-time input like GetKeyDown is missed by this method since there might be multiple Update frames in between two FixedUpdate calls => The GetKeyDown was true in a frame where there was no FixedUpdate call.
=> Thumbrule: Get (single-event) User input in Update. Then if you are dealing with physics apply this input in FixedUpdate (store it in fields meanwhile).

How can I execute code if something is true, continue executing the code indefinitely, but stop evaluating the if statement?

I'm just starting out please excuse vast ignorance.
I'm writing a c# script in unity as part of the essentials training. I'm doing the 3d audio module and I thought I'd try and get a little bit fancier than the scope of this particular lesson which is supposed to be having an object fly through a window in a pre-built scene and make a 3d sound as it moves.
I wanted to make the movement of the object conditional upon a player moving close to it in 3d space. I figured out how to trigger the movement of an object in a script with an if statement that changes the transform parameters of the object the script is attached to when a 'distanceFromObject' variable is < 2. It works, however the script runs in the update section of the script which runs once every frame. This means that the object's transform parameters are changed every frame as expected but of course stops doing so when the distance between the object that's moving and the player exceeds 2.
I see the mistake I've made because if the object moves away when the player gets close then it will inevitably eventually move far enough away that the distanceFromObject variable will grow bigger than 2 whereupon it stops and just hovers in place. I don't know how to fix it though.
I need the script to check the distance between the object and the player every frame so that it will trigger the instance the player gets close enough, and when they get close enough, I need the object to move away, however once it has been triggered to move, I need the object to continue moving, but the script to stop checking what the distance is anymore.
The script looks like this
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class FlyOff : MonoBehaviour
{
public Vector3 rotateChange;
public Vector3 positionChange;
public float distanceFromObject;
public GameObject character;
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
distanceFromObject = Vector3.Distance(character.transform.position, this.gameObject.transform.position);
print (distanceFromObject);
if (distanceFromObject < 2)
{
transform.Rotate (rotateChange);
transform.position += positionChange;
}
}
}

Use flags instead of writing your logic in the if statement :
public class FlyOff : MonoBehaviour
{
// fields removed for more readability
// use a flag that's set to true/false
private bool isCloseEnough = false;
void Update()
{
distanceFromObject = Vector3.Distance(character.transform.position, this.gameObject.transform.position);
print (distanceFromObject);
// set the flag to true when player is close enough
if (distanceFromObject < 2)
{
isCloseEnough = true;
}
// even if the player gets far, the flag will remain true
if (isCloseEnough)
{
transform.Rotate (rotateChange);
transform.position += positionChange;
}
}
}
You can even apply the opposite logic to stop the object to move away when it has reach a certain distance :
if (distanceFromObject < 2)
{
isCloseEnough = true;
}
else if (distanceFromObject > SomeValue)
{
isCloseEnough = false;
}

If I understand correctly you could just add a bool flag and set it once you are close enough. Then you can start moving and skip further distance checks but keep moving forever.
private bool flyAway;
void Update()
{
if(!flyAway)
{
distanceFromObject = Vector3.Distance(character.transform.position, transform.position);
print (distanceFromObject);
if (distanceFromObject < 2)
{
flyAway = true;
}
}
else
{
transform.Rotate (rotateChange);
transform.position += positionChange;
}
}
In general: Avoid using print every frame! Even if you user doesn't see the log in a built app it is still causing overhead!

Physics inconsistent even when using FixedUpdate() or Time.DeltaTime()

I want to move a rigidBody2D for a fixed amount of time with a fixed amount of velocity, when the player presses a button. I am calling the method in FixedUpdate() and the results are not consistent. Sometimes the rigidBody will travel more and sometimes less (Here is a relevant part of my code how i went about do this)
void Update()
{
GetPlayerInput();
}
private void FixedUpdate()
{
GroundCheck();
ApplayNormalPlayerMovement();
ApplyMove(); // This is the method of interest - I tried calling this in Update() with Time.DeltaTime - still inconsistent results.
MoveCooldownCounter(); // I tried calling this in Update() - inconsistent results also
}
IEnumerator MoveRB()
{
savedVelocityX = rb.velocity.x;
rb.gravityScale = 0;
savedXinput = xInput;
while (moveTimer >= 0)
{
if (xInput != 0)
xInput = 0;
cc.sharedMaterial = noFriction;
if (facingRight)
{
rb.velocity = new Vector2(moveSpeed, .0f); // I tried multiplying the moveSpeed by Time.DeltaTime and FixedDeltaTime - still inconsistent results.
} else
{
rb.velocity = new Vector2(-moveSpeed, .0f);
}
moveTimer -= Time.fixedDeltaTime;
yield return null;
}
moveTimer= moveDuration;
rb.gravityScale = gravity;
rb.velocity = new Vector2 (savedVelocityX, .0f);
xInput = savedXinput;
moveCooldownInternal -= Time.deltaTime; // I tried changing this to a specific float - still inconsistent results in physics..
}
private void MoveCooldownCounter()
{
if (moveCooldownInternal != moveCooldown)
{
moveCooldownInternal -= Time.deltaTime;
if (moveCooldownInternal <= 0)
{
moveCooldownInternal = moveCooldown;
}
if (moveCooldownInternal == moveCooldown && isGrounded)
canMove = true;
}
}
private void ApplyMove()
{
if (b_Fire3 && canMove)
{
StartCoroutine("MoveRB");
canMove= false;
}
}
Side note: right now i experience player input loss on occasions because i call this ApplyMove() in FixedUpdate() (will have to find a workaround for that as well - naturally if I can call the ApplyMove in Update() and get consistent results than this issue would be fixed).
Pleas excise my newbiness, i am trying to learn :)
Thank you in advance!
Add comment

Unity is a game engine. All game engines are based on the game loop - however Unity somewhat hides if from you, behind the 3 Update functions.
Not all parts are equally important. Drawing is generally skipped when the GPU is not ready or the FPS are capped. And Drawing and physics are generally calculated independantly of one another (unless you really messed up the development).
With Physics and Animations, you generally want to stuff to be consistent to the Game Tick Counter, not real time. All movement of game pieces and all animation should count in game ticks. Real Time is a nice figure and all, but ticks can have wildly different processing times. Especially since the CPU side drawing work also has to run in the same thread.
Just figure out your maximum ticks/second. And if you want to run something to run for "roughly" 10 ingame seconds, you multiply that value. It does not mater if the game on this machine needs 2 seconds for 200 ticks or 2 minutes for 200 ticks - with the number of ticks, the results will be consistent (unless the math itself is inprecise, like floating point math).

If it's not multiplayer game, it does not have to be hackproof and thus easiest fix is to capture the first frame of the button pressed and apply the force only on that frame, because of that we have to capture input on the Update function and also there immadietly apply the force even though it's suggested to do physics stuff in fixed update, but if you use delta time in update function for calculation it should be fine!
Now I think you know how to do that but I'll write it anyway we can either use apply force or set the velocity,
void Update()
{
if(Input.GetKeyDown("w"))
rb.velocity = new Vector2(rb.velocity.x, rb.velocity.y + 5f*Time.deltaTime);
}
Note: I didn't test it but it should be allright since GetKeyDown returns true only on the first frame when the button was pressed,
If it was just GetKey and in case of jump we would check the grounding of player, we could be during jump and still be grounded on the second frame even if we jumped because of not really precise ground checking.
PS. Use fixedDeltaTime in fixedUpdate method!

Unity - Logic to pick up objects and drop them one by one at different positions

Please look at example - http://www.mathplayground.com/mancala.html
Can anyone suggest the logic to :
1) spawn objects at positions
2) Pick up all objects on click and distribute them one by one.
3) Is it better to create all objects or instantiate them on the fly. ?
I tried code below but it just instantiates all objects at once.
if (HoleHandler.gemCount_Hole1_Update_Flag == true)
{
foreach (GameObject g in gemList1)
{
Destroy(g);
//want to add a time delay of 2 secs here
}
if (gemCount_Hole1 > 0)
{
for (int i = 0; i < gemCount_Hole1; i++)
{
int Gem_prefabIndex = UnityEngine.Random.Range(0, 9);
gemList1.Add(Instantiate(Gem_prefabList[Gem_prefabIndex], new Vector2((xPos_Hole1 + (Random.Range(-20, 20))) * 2.0F, (-229 + (20 * i))), Quaternion.identity));
}
}
}

I'm not 100% sure of what you're trying to achieve but I will answer as best I can.
For a start, any gameobject you are going to be instantiating (spawning) at run time should ideally be done so from a prefab.
Secondly, to spawn them at random intervals you want to be checking if they should be spawned at different time frames. This can be achieved through a co-routine or the Update function. I would recommend Update if this is new to you.
Update is called every frame.. and it's with this that you can achieve timed events. You can use a variety of helper methods to determine the time since the last frame or the real time elapsed.
For example
public class MyGameObject : Monobehaviour {
void Start() {
//This is called first, use it to set up whatever you want.
}
void Update() {
//This will be called every frame.
//Each frame or time lapse will determine if I should spawn
// a new gameobject.
}
}
Update
After looking at the game you have linked in your post I can offer the following advice.
Something like the following may point you in the right direction.
public int[] gemsInCups = new int [] {4,4,4,4,4,4,0,4,4,4,4,4,4,0};
public void Distribute(int position){
int gems = gemsInCups[position];
for(int i = position + 1; gems > 0; i++){
gemsInCups[position] ++;
gems --;
//Check the end of the array has not been reached.
//If it has, start distributing again from the first position provided
// there are still gems to distribute.
}
}
You will need some additional logic to finish this.
What you should remember is, I usually find it much more manageable keeping my data and my view (gameobjects) under different scopes... but the view will change to reflect the data and does not directly alter it. Now you know how many gems there are in each cup, you can simply update this each frame.

How can I get the camera to pause on 3 objects on the x axis?

I am a new student working on a class project. I have 1 script attached to the camera in my only scene. I want the camera to pause over the 1st object, scroll to the 2nd object and pause then scroll to the 3rd object and pause then end. Putting this code in the UPDATE, the camera never stops. Here in the START, it hesitates around 15 sec and then it goes right to the last object, then the function stops. Note the delay set for 10 seconds. I tried putting the code in a function and calling the function from START… but no good. What am I doing wrong? HELP ME OB1....
One more thing... Is START the best place to play sound?
using UnityEngine;
using System.Collections;
// I want the camera to pause over the 1st object, scroll to the 2nd object and pause
// then scroll to the 3rd object and pause then end. Putting this code in the UPDATE
// the camera never stops. Here in the START, it hesitates around 15 sec and then it
// goes right to the last object, then the function stops. Note the delay set for 10
// seconds.
public class CameraControl : MonoBehaviour
{
public float speed; // How fast to move the camera
public int moves; // How many moves to make
public float MyWait; // How long to pause over object
// Use this for initialization
void Start()
{
StartCoroutine(MyDelay());
for (int y = 1; y <= 2; y++) // go to the next two objects
{
for (int i = 1; i <= moves; i++) // Move the camera to the next position
{
Camera.main.transform.Translate(new Vector3(1.0f, 0.0f, 0.0f) * speed * Time.deltaTime);
Debug.LogFormat("moves = {0} ", i);
}
StartCoroutine(MyDelay());
}
}
IEnumerator MyDelay()
{
yield return new WaitForSeconds(10.0f);
}
}

Try placing this code on your camera and place all the game objects you'd like the camera to move to in the Objects list. If you'd like the camera to be a little further back so it can see the object, create a new Vector3 instead of simply giving the exact position and then give that new Vector3 the x, y and z of the iterating object and then add distance to which ever axis you'd like for the camera to be distanced from the object.
public float MyWait = 5; // How long to pause over object
public float speed = 5f; // How fast to move the camera
public List<GameObject> Objects; //List of each object for the camera to go to
void Start()
{
StartCoroutine(MoveToObject(0));
}
IEnumerator MoveToObject(int iteratingObject)
{
//Wait for however many seconds
yield return new WaitForSeconds(MyWait);
bool atDestination = false;
//Move the camera until at destination
while (!atDestination)
{
yield return new WaitForFixedUpdate();
transform.position = Vector3.MoveTowards(transform.position, Objects[iteratingObject].transform.position, Time.deltaTime * speed);
if (transform.position == Objects[iteratingObject].transform.position)
atDestination = true;
}
//Continue iterating until moved over all objects in list
if(iteratingObject != Objects.Count - 1)
StartCoroutine(MoveToObject(iteratingObject + 1));
}

I think you're going to need to put some code in the Update function for this to work smoothly.
Time.deltaTime will only really make sense in an Update function, using it here and trying to do everything in the Start function won't work. Also setting the Translate transform will instantly set the position to the given value. Look up linear interpolation (lerp).
I would suggest you have a member that you use to track the current state, i.e. which object you're looking at, but an Enum of states might be easier to read.
Then you can keep a member for how long you've been in that state, which you can increase in the Update.
Then within the Update you can check whether it is time to change state or update your moving camera.
Good luck!