Unity Jumping Issue - Character won't jump if it walks to the platform - unity3d

Question

(This is a 2D project)
I have a jumping issue where if my character WALKS into an X platform, she won't jump, but when she JUMPS ONTO the X platform, she can perform a jump.
For the platforms I am currently using 2 Box Collider 2Ds (one with "is trigger" checked)
For the character I am currently using 2 Box Collider 2Ds (one with "is trigger" checked) and Rigidbody 2D.
Below is the code for jumping and grounded I am currently trying to use.
{
public float Speed;
public float Jump;
bool grounded = false;
void Start()
{
}
void Update()
{
if (Input.GetKeyDown(KeyCode.UpArrow))
{
if (grounded)
{
GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, Jump);
}
}
}
void OnTriggerEnter2D()
{
grounded = true;
}
void OnTriggerExit2D()
{
grounded = false;
}
}
Issue arises on the same part of every platform. (Each square represents a single platform sprite and they have all the same exact characteristics, since I copy pasted each one of them). Please check the photo on this link: https://imgur.com/a/vTmHw

Answer 1

It happens because your squares have seperate colliders. Imagine this:
There are two blocks : A and B. You are standing on block A. Now you try to walk on block B. As soon as your Rigidbody2D collider touches block B, your character gets an event OnTriggerEnter2D(...). Now you claim, that you are grounded.
However, at this moment you are still colliding with block A. As soon as your Rigidbody2D no longer collides with block A, your character receives OnTriggerExit2D(...). Now you claim, that you are no longer grounded. But in fact, you are still colliding with block B.
Solution
Instead of having bool variable for checking if grounded, you could have byte type variable, called collisionsCounter:
Once you enter a trigger - increase the counter.
Once you exit a trigger - decrease the counter.
Do some checking to make sure you are actually above the collider!
Now, once you need to check if your character is grounded, you can just use
if (collisionsCounter > 0)
{
// I am grounded, allow me to jump
}
EDIT
Actually, after investingating question further, I've realized that you have totally unnecessary colliders (I'm talking about the trigger ones). Remove those. Now you have only one collider per object. But to get the calls for collision, you need to change:
OnTriggerEnter2D(...) to OnCollisionEnter2D(Collision2D)
OnTriggerExit2D(...) to OnCollisionExit2D(Collision2D)
Final code
[RequireComponent(typeof(Rigidbody2D))]
public sealed class Character : MonoBehaviour
{
// A constant with tag name to prevent typos in code
private const string TagName_Platform = "Platform";
public float Speed;
public float Jump;
private Rigidbody2D myRigidbody;
private byte platformCollisions;
// Check if the player can jump
private bool CanJump
{
get { return platformCollisions > 0; }
}
// Called once the script is started
private void Start()
{
myRigidbody = GetComponent<Rigidbody2D>();
platformCollisions = 0;
}
// Called every frame
private void Update()
{
// // // // // // // // // // // // // //
// Need to check for horizontal movement
// // // // // // // // // // // // // //
// Trying to jump
if (Input.GetKeyDown(KeyDode.UpArrow) && CanJump == true)
Jump();
}
// Called once Rigidbody2D starts colliding with something
private void OnCollisionEnter2D(Collision2D collision)
{
if(collision.collider.tag == TagName_Platform)
platformCollisions++;
}
// Called once Rigidbody2D finishes colliding with something
private void OnCollisionExit2D(Collision2D collision)
{
if(collision.collider.tag == TagName_Platform)
platformCollisions--;
}
// Makes Character jump
private void Jump()
{
Vector2 velocity = myRigidbody.velocity;
velocity.y = Jump;
myRigidbody.velocity = velocity;
}
}
Here can be minor typos as all the code was typed inside Notepad...

Answer 2

I think there are a couple of issues here.
Firstly, using Triggers to check this type of collision is probably not the best way forward. I would suggested not using triggers, and instead using OnCollisionEnter2D(). Triggers just detect if the collision space of two objects has overlapped each other, whereas normal collisions collide against each otehr as if they were two solid objects. Seen as though you are detecting to see if you have landed on the floor, you don't want to fall through the floor like Triggers behave.
Second, I would suggest using AddForce instead of GetComponent<Rigidbody2D>().velocity.
Your final script could look like something like this:
public class PlayerController : MonoBehaviour
{
public float jumpForce = 10.0f;
public bool isGrounded;
Rigidbody2D rb;
void Start()
{
rb = GetComponent<Rigidbody2D>();
}
void OnCollisionEnter2D(Collision2D other)
{
// If we have collided with the platform
if (other.gameObject.tag == "YourPlatformTag")
{
// Then we must be on the ground
isGrounded = true;
}
}
void Update()
{
// If we press space and we are on the ground
if(Input.GetKeyDown(KeyCode.Space) && isGrounded)
{
// Add some force to our Rigidbody
rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
// We have jumped, we are no longer on the ground
isGrounded = false;
}
}
}