The character sometimes jumps double the height. How to fix it?

Question

C++ / C#

The character randomly jumps to double the height from the prescribed one.

Wrote the most standard jump code:

private void Jump() {
        rigidbody.AddForce(transform.up * jumpForce, ForceMode2D.Impulse);
}

Also quite common code for checking the ground under your feet:

private void CheckGround() {
        Collider2D[] colliders = Physics2D.OverlapCircleAll(transform.position, 0.3f);

        isGrounded = colliders.Length > 1;
}

Calling the jump function:

private void Update() {
        if (isGrounded && Input.GetButton("Jump")) Jump();
}

Calling the function to check the ground under your feet:

private void FixedUpdate() {
        CheckGround();
}

Thank you in advance.

Answer 1

I solved this problem. As it turned out, everything was very simple... I called the jump function in Update, which is strongly discouraged... And along with framerate jumps and drops, the character jumped up and down. After I transferred all the movement to FixedUpdate, the problem capitulated.

Answer 2

Usually this situation occurs due to incorrect ground testing. For example, the player has not yet fallen, but the collider has already worked. Or the player fired a pistol and the bullet was detected as ground. Or a vertical wall hit the collider.
I advise you to rewrite under raycast under your feet. Also check if the impulse works correctly. Maybe your project is better off using speed.

Answer 3

private void Jump() {
        rigidbody.AddForce(transform.up * jumpForce, ForceMode2D.Impulse);
}

Now make it so that a double call to this function would give the same speedup as a single call. The simplest is to limit the character's upward acceleration to some constant. If the acceleration exceeds the threshold, then truncate to this value.