applying velocity to rigidbody makes it float instead of dashing - unity3d

Question

Im trying to code so that my Character dashes to the right when pressing the Left mouse button, but instead of dashing it just starts slowly glieding or lets say floating.
This is the code i´ve used;
if (Input.GetMouseButton(0))
{
rb.velocity = Vector2.right * DashSpeed;
}
Im not sure but a other part of my code might be the reason for this problem but if so i would like to know how i could solve it. Thats the part im talking about
rb.velocity = new Vector2(moveInput * speed, rb.velocity.y);
thats the code im using for movement.
void Start()
{
cam = Camera.main;
rb = GetComponent<Rigidbody2D>();
}
private void Update()
{
horizontal = Input.GetAxisRaw("Horizontal");
animator.SetFloat("Horizontal", Input.GetAxis("Horizontal"));
if (Input.GetKeyDown(KeyCode.Space) && isGrounded == true)
{
float jumpVelocity = 7f;
rb.velocity = Vector2.up * jumpVelocity;
jumpsound.Play();
}
Vector3 worldPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
if (Input.GetKey(KeyCode.RightAlt))
{
Dashing();
}
}
void FixedUpdate()
{
isGrounded = Physics2D.OverlapCircle(groundCheck.position, CheckRadius, whatisGround);
moveInput = Input.GetAxisRaw("Horizontal");
rb.velocity = new Vector2(moveInput * speed, rb.velocity.y);
if (Input.GetKeyDown(KeyCode.Escape))
{
SceneManager.LoadScene("Main menu");
}
}
void Dashing()
{
rb.AddForce(Vector2.right * DashSpeed, ForceMode2D.Impulse);
}

Answer 1

The issue with your current code is you are directly changing velocity in a few places. Some basic physics, the integral of position vs. time graph is velocity, and the integral of velocity is acceleration vs. time. To get a more realistic movement, it is better to apply a Force to objects. When doing this, the physics engine Unity uses can add a new force at a given time, then using acceleration can accelerate the object in that direction over time, then can change the velocity over time which will result in the position changing over time.
The example code you posted, you are directly setting velocity in a few places.
rb.velocity = Vector2.up * jumpVelocity; (Jump)
rb.velocity = new Vector2(moveInput * speed, rb.velocity.y); (Movement)
rb.velocity = Vector2.right * DashSpeed; (Dash)
When directly setting these values, the new values overwrite the old ones. As your movement code is not in any sort of if conditional it will continually write to the velocity causing the dash to never change anything regardless if you use add-force or change velocity directly.
I would consider making both your jump and dash use AddForce, and if you like the feel of your movement by applying velocity directly, then add the velocity do not set it.
Your previous line rb.velocity = new Vector2(moveInput * speed, rb.velocity.y); would then become rb.AddForce(new Vector2(moveInput * speed, 0), ForceMode2D.Impulse);. Similarly you can update your jump and dash to match this. Let me know if you get this working or have more questions.

Answer 2

It could be a problem with your animation. Link to a thread on unity answers:
https://answers.unity.com/questions/674516/rigidbody-character-problems-constant-floating-jum.html
You should go over to the animation place and hit bake into pose.
You should use the Rigidbody2D.AddForce(Vector2, ForceMode2D). What this does is moving the GameObject in the direction of the Vector2, with the force mode of ForceMode2D. What is different about this from just translating it, is that it interacts with physics and improves the quality of your game. Here is a link, and the script:
https://docs.unity3d.com/ScriptReference/Rigidbody2D.AddForce.html
Rigidbody2D rb;
float dashSpeed;
void Update()
{
if (Input.GetMouseButton(0))
{
rb.AddForce(Vector2.right * dashSpeed);
}
}
And if the other part of the code you were talking about, if that is glitching, then do the same trick.