Check if 2D Character is grounded

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To do this i looked a lot on the internet. I tried to check the velocity, but checking 2d velocity doesn't seem to work for some reason. But what i found was i should probably try linecast. But all the things online were all C# which i do not want. Is there like a simple string of code i can put into a script to check if the attached gameobject is grounded? Easiest method please haha

Answer 1

Best Answer

Answer by Josh707 · May 15, 2014 at 07:45 AM

I think you will want to use Physics2D.OverlapArea rather than a raycast at a single point. I can guarantee a raycast would end up with you sitting on the corner of your collider and it doesn't say you're grounded. Basically you can check a rectangular area for collisions and use that to determine if you're grounded.

 //Corners of the rectangle to check
 public var top_left : Transform;
 public var bottom_right : Transform;
 public var ground_layers : LayerMask;
 var grounded : bool;
 
 function FixedUpdate(){
     grounded = Physics2D.OverlapArea(top_left.position, bottom_right.position, ground_layers);    
 }

Depending on the shape of your characters collider you might want to use Physics2D.OverlapCircle instead.

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matta9001 · May 15, 2014 at 12:53 PM 0

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Uh sorry, but how do i set transforms to the corner of an object? Should i put blank gameobjects with colliders and parent it? Once again i'm sorry I am a noob and i really appreciate the help.

Josh707 · May 15, 2014 at 02:19 PM 0

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It's alright! No, you don't need any colliders or anything, just 2 empty GameObjects which are a child of your sprite/character. OverlapArea takes 2 positions to make a rectangle, which should be opposite corners. You don't actually need 2 GameObjects for this but it makes it quicker to tweak.

matta9001 · May 16, 2014 at 06:11 AM 0

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You are flippin awesome dude, i was so intent on getting raycast to work i didn't even think of a different easier solution. Thanks a lot it helps so much

Josh707 · May 16, 2014 at 07:38 PM 0

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Haha no problem! Also I just read OverlapArea allocates memory every time it is called so you should check out OverlapAreaNonAlloc ins$$anonymous$$d, since it's being called very frequently.

LeleUnity · Jun 04, 2020 at 08:37 PM 0

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@Josh707 @matta9001 OverlapAerea return a collider not a bool... the code is not working..

Answer 2

Answer by siddharth3322 · May 14, 2014 at 05:21 AM

Basically if you are developing character based game then you must have to view this video. As per my consideration you definitely find your all doubts clear.

2D Character Controller

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matta9001 · May 14, 2014 at 12:18 PM 0

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Problem is its C#, im sure i will be able to pick some stuff out though i hope.

Answer 3

Wiki

Answer by Slulego · May 14, 2014 at 03:37 PM

I think you want to raycast. Try adding a raycast pointing down to check if something is below it.

Physics2D.Raycast

If it shows up as C#, there should be a drop down near the top left that says "Scripting Reference Using-dropdown"

 function FixedUpdate() {
     // Cast a ray straight down.
     var hit: RaycastHit2D = Physics2D.Raycast(transform.position, -Vector2.up, 0.1);
     
     // If it hits something...
     if (hit != null) {
         isOnGround = true;
     }
 }

Hope this helps.

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matta9001 · May 14, 2014 at 08:54 PM 0

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See heres the thing, the code you gave me just fires a function when the raycast hits something. Do you you know how to calculate how long that raycast is and i can make a < or > if statement on the value? So i can make it like if(distance > .1){ isGrounded = true; } any idaes?

Slulego · May 15, 2014 at 02:48 AM 0

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Oops, my bad. Updated.

matta9001 · May 15, 2014 at 03:04 AM 0

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I really hate saying this but...this doesn't work either. I put the character up in the air and a debug.log to see if the boolean changed but...it doesn't :(, i put an else statement to see if it would change but i couldn't get it to work. I'm not a coding genius and im tryin all i can. I just want it so that if its touching the ground, isGrounded = true, and if its not, than isGrounded = false, i can handle all the other scripting with just that boolean but this is literally the only issue ive come across. I dunno what it is it just doesn't seem to work.

Pyrian · May 15, 2014 at 05:11 AM 0

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The sample code in the documentation is incorrect on this point. "if (hit != null)" is useless code because Raycast ALWAYS returns an object, it does not return null.

I'm not entirely clear on the JavaScript implementation, but in C# you can simply use "if (hit)" to accomplish that check correctly. If that doesn't work, check the RaycastHit2D's collider; if it's null, there's no hit. So, "if (hit.collider != null)".

Interestingly, this is correctly documented (without sample code) here:

RaycastHit2D.collider

Slulego · May 17, 2014 at 02:41 PM 0

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$$anonymous$$aybe try

 if(hit != null && hit.transform != null)

Also I'm not sure if you have background sprites and whether that will effect it any.

Answer 4

Answer by Zachary Hoffman · May 15, 2014 at 03:06 AM

Add a character controller and check the .isgrounded property of it.

Here is the Unityscript reference

https://docs.unity3d.com/Documentation/ScriptReference/CharacterController-isGrounded.html

Here is JavaScript

 function Update () {
         var controller : CharacterController = GetComponent(CharacterController);
         if (controller.isGrounded)
             print("We are grounded");
     }

NOTE: Must add a charactercontroller to your object for this to work

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matta9001 · May 15, 2014 at 03:56 AM 0

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character controller is 3d mate, im making a 2d sprite controller

Answer 5

Answer by Aatifahmad · Oct 01, 2019 at 04:40 PM

If raycast does not work! use this.

private void OnCollisionEnter2D(Collision2D other) { if (other.gameObject.tag == "platForm") { isOnGround = true; } }

 private void OnCollisionExit2D(Collision2D col)
 {
     isOnGround = false;
 }

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Check if 2D Character is grounded

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