Develop Reference

Why does my script, which aims to remove gravity when the game starts, not work?

I'm trying to create a script in Unity wherein the gravity will go to zero when the game starts. The problem is, the gravity was still there after I launched the game.
This is for a Unity3D game. I've already tried to change the variable name, add using System; and moved my script to the top of the Rigidbody component, but none of these things worked.
public class PlayerGrav : MonoBehaviour
{
public Rigidbody rb;
void Start()
{
rb.useGravity = false;
}
void Update()
{
}
}
I expected the gravity to be removed when the game launches, but in the actual output the gravity still remained, and the cube still fell downwards.

create a new scene
create a new cube
add rb = this.GetComponent<Rigidbody>() to your start function in your PlayerGrav script
attach your PlayerGrav script to the new cube
Hit play, and take look at the "use gravity" property from your new cube's inspector window (make sure the inspector isn't locked to other game object)
If the above tryout succeeds, then you need to check the other code/objects in your original scene. If there are massive other objects in your original scene, then I will suggest disable other objects first, and re-enable them back group by group to see which object/monobhevaiour is causing the issue.

I know this is an old question but I looked forever trying to find an answer to this. I am new to unity so it took me a long time to figure this out but I am using a Rigidbody 2d so this is what worked for me
gameObject.GetComponent<Rigidbody2D>().gravityScale = 0;

Trying to load a new scene when I enter a cube in Unity

So i have this code to enter a new scene:
using System.Collections;
using UnityEngine;
// add this line to use the SceneManagment library
using UnityEngine.SceneManagement;
public class LoadScenes : MonoBehaviour {
[SerializeField] private string loadLevel;
void onTriggerEnter(Collider other) {
if (other.CompareTag ("Player")) {
SceneManager.LoadScene (loadLevel);
}
}
}
I then add this script to the cube and select it a trigger. I then type in the scene that I want it to send me too, but when i walk into it nothing happens at all. I have tried different variations but it just doesnt seem to work.
My character that I am using is a unity asset called man in suit but I have selected its tag as "Player". Any suggestions would be great!

The Handler for your trigger won't be invoked
As Sunimal allready noted you need to fix the typo.
void OnTriggerEnter(Collider other) {
if (other.CompareTag ("Player")) {
SceneManager.LoadScene (loadLevel);
}
}
Ensure your Scene is included and checked in the Build Settings
As you can see in the Screenshot below i have added a SampleScene to my build settings. There are 2 ways of adding scenes into the build
By clicking "Add Open Scenes" you can add the scene which is
currently open to that list.
Drag & Drop the scene from your ProjectView into the List
Ensure your SceneName is set correctly
Your loadLevel field would in my case need to have the value "Scenes/SampleScene".
[SerializeField] private string loadLevel;
The player needs a collider
As you use the OnTriggerEnter method, your Player object needs to have some sort of Collider attached to it. This can be a BoxCollider, SphereCollider or some other Collider. Note that the "Is Trigger" checkbox needs to be checked. Else it won't act as trigger.
Edit: Thanks Eddge for correcting me. See this answer for a deeper explanation about Triggers.
Programatically ensure you have a BoxCollider component beside your LoadScenes component
You can add the RequireComponent Attribute at your class. It basically ensures you have the given type added as a component. This will also automatically add a box collider to an object, when you add this script.
[RequireComponent(typeof(BoxCollider))]
public class LoadScenes : MonoBehaviour {
/// your other code is here
}
Thanks to Sunimal for this hint!
What if that did not solve the problem?
If all this does not help, please provide an screenshot of the inspector of your Playerobject. That way we can see what components are attached to that object and how they are "configured"

SceneManagement
To use the SceneManager to load a scene you must ensure that your scene is in the build settings, per Tobias's answer.
Triggers
In all software development case does matter and it is incredibly important. OnTriggerEnter is not the same as onTriggerEnter, also note OnTriggerEnter(Collider col) is not the same as OnTriggerEnter(Collision col)
In order to use any of the trigger methods there are 3 things that are a must:
Both Objects have to have colliders.
One of the colliders have to be marked as a trigger.
One of the objects have to have a rigidbody.
The trigger event is sent to the object with the rigidbody and whatever object is the trigger, in the circumstance that both objects are triggers both will receive it.

Unity - Clicking on one object activates others

I am trying to create a Minesweeper + clicker/idle game for practice. For now, I can't get the clicking to work properly. I spawned in all objects through code meaning they are all the same prefabs but at different locations. When I click them the code activates for all of them and all of the tiles change to being open. I am not sure if I'm using the wrong click function here, as I know there is also an OnMouseDown() function instead of Input.GetMouseButtonDown(0) but the only one where the code activates is in the second one.
public class TileClick : MonoBehaviour {
public GameObject openTile;
// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
if (Input.GetMouseButtonDown(0)) {
Instantiate(openTile, transform.position, Quaternion.identity);
Object.Destroy(this.gameObject);
}
}
}
That's my clicking detection. While it does detect clicks, as I said before, it detects them for ALL tiles and activates them all. I only want it to activate on one of them. I've seen RayCasting stuff but I really need more explanation on how that thing works (if that's the solution).

If the TileClick script component is attached to your prefab, then for every tile you instantiate, you have a corresponding TileClick component attached.
When you click, the input is detected by all of these blocks simultaneously, and each of them calls Instantiate but the transform.position is the one corresponding to the tile that makes the call. This is why it seems like all the tiles open up simultaneously, because you are, in fact, instantiating an "open" tile on each of them every time you click.
You should keep all your user input code in a separate MonoBehaviour, and attach that to a single empty GameObject in your scene. For detecting the hit, you should attach a 2DCollider component to your tile prefab (you can decide the type according to the shape of your tiles), and then just use a simple RayCast in your user input code to instantiate an "open" tile at the position where the hit occurs:
void Update () {
if (Input.GetMouseButtonDown(0)) {
RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition),
Vector2.zero);
if(hit.collider != null)
{
Instantiate(openTile,
hit.collider.gameObject.transform.position,
Quaternion.identity);
}
}
I highly recommend understanding how RayCast works since it is a very useful tool. Here's a good place to start: https://docs.unity3d.com/ScriptReference/Physics2D.Raycast.html

On-collision script not working?

in advanced I would like to say if this is a really simple question with a simple answer, I apologize as I have just now gotten into programming.Basically, I'm trying to create a script that a block named blue(picture below) on collision with the FPSController, will get destroyed, here is my script:
using UnityEngine;
using System.Collections;
public class Cube : MonoBehaviour {
void OnCollisionEnter (Collision col) {
if(col.gameObject.name == "Blue") {
Destroy(col.gameObject);
print ("collison detected");
}
}
}
for some reason, though, whenever the fps controller collides with the object known as "Blue" nothing happens, the print() function is not triggered nor is the destroy() function
Thank you in advaned ;)

Rigidbody` is missing from your Cubes.
1.Attach Rigidbody component to both cubes.
2.Also,set both Cubes Rigidbody to Is-kinematic. You must set both Cubes Rigidbody to Is-kinematic so that the Character Controller wont be able to move it. Note that if your cube is falling down after adding Rigidbody, simply disable Use Graivty on the Rigidbody.
Important:
3.Delete FPSController. Since you will be interacting with other Rigidbody GameObjects, use RigidBodyFPSController. It can be found in Assets\Standard Assets\Characters\FirstPersonCharacter\Prefabs. Drag RigidBodyFPSController to the Scene then attach Cube script to it.
You will notice there is a Rigidbody attached to RigidBodyFPSController. Don't modify the settings of it.
That's it. Everything should be working as expected.
Cube settings:
RigidBodyFPSController Settings:

Instantiate gameobject from a script that is on that gameobject

I have a script called DialogueController, which is attached to a canvas. I would like to instantiate that canvas from the DialogueController script. Whenever I attempt to do this, all of the public objects that were assigned to the canvas through the Unity editor are set to null (including the canvas itself, which is what I am trying to instantiate).
Is there a simple way to do this? I have an alternative solution, but being able to do this would keep my code slightly more compartmentalized.

You could initialize these variables from the script itself, using the resources folders (and the Resources.Load() method). Something like that:
//The canvas is at the path "Assets/Resources/canvas".
function Start () {
your_canvas = Instantiate(Resources.Load("canvas"));
}

From the comments, it seems like you need an initial "seed" instance of that Canvas which contains your script to instantiate more copies if you need. Part 2 is most common for your needs
The easiest way is to have one instance of said canvas already in the scene. You could have the drawable/visible canvas part "disabled" by unticking the little checkbox in the inspector, and then have it enable itself in a function of a script on the GameObject...
void Start ()
{
thisCanvas = GetComponent<Canvas>();
thisCanvas.enabled = true;
}
of course, another way would just be to instantiate one copy from another script which you already have in the scene - classic case:
Create a BLANK GameObject in your scene (CTRL+Shift+N), [F2] rename it "GameManager" (SOME unity functions still bug out when there are spaces in GameObject names BTW) and then attach a new script called GameManager.
This script is basically just here to make sure the right scenes load, and instantiate certain prefabs, make network connections, set player variables that you haven't done from the editor etc etc
so:
using UnityEngine;
using System.Collections;
public class GameManager : MonoBehaviour
{
public GameObject myObject;
void Start ()
{
Instantiate(myObject, transform.position, transform.rotation);
}
}
now drag+drop your "prefab" which you want to instantiate into the slot on your "GameManager" in the inspector.
Note that it doesn't have to be when the game starts, another example is the GameManager script having a function listening for whenever a login is needed, and at that time - it instantiates your login dialog.