Unity3D C# Drag object smoothly on it's x axis that's already bouncing

Question

In my scene, I have a bouncing ball that collides with a cube. On each collision the ball returns to the same height. How can I get the ball to smoothly move along the x-axis by dragging my finger across the screen, while at the same time having no effect on the y or z values?

The y position is changing every frame depending on the state of the jump, so setting it's y position to transform.position.y in the Update function causes the movement to be jittery if the frame renders when it isn't caught up with the position of the ball.

Also, I set the interpolate value of the rigidbody to interpolate to get a smoother jumping motion, not sure if this is relevant to my problem or not.

Here is where I am at so far with little success. A few mobile games that replicate what I'm trying to achieve in terms of ball movement are Hop, Color Hop, and Splashy!

void Update()
{  
    if (Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Moved)
    {
        // Control sliding using touch input.
        Vector2 touchDeltaPosition = Input.GetTouch(0).deltaPosition;
        transform.Translate(touchDeltaPosition.x * slidingSpeed, 0, 0);
    }
    transform.position = new Vector3 (Mathf.Clamp(transform.position.x, - xPosLimit, xPosLimit), transform.position.y, transform.position.z);
}

Answer 1

You've almost got it. Given that you want the absolute position, I would switch from using the touch delta position to the touch position (absolute). I then normalized it and used your xPosLimit variable to determine the final xPosition.

Treat it as pseudocode tho, I wrote it from memory.

void Update()
{  
    if (Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Moved)
    {
        // Control sliding using touch input.
        Vector2 touchPos = Input.GetTouch(0).position;

        //normalize the X coord (make it between 0 and 1), Y coord is irrelevant
        float normalizedX = touchPos.x / Screen.width;

        //interpolate between -xPosLimit and +xPosLimit by the normalizedX coord
        //no need to clamp it
        float xPos = Mathf.lerp(-xPosLimit, xPosLimit, normalizedX);

        //set the new position, leave Y and Z alone
        transform.position = new Vector3(xPos, transform.position.y, transform.position.z);
    }
}

Update: See comment below, the issue was solved with the above code AND by disabling interpolation on the rigidbody.