koobas.hobune.stream
Why does multiplying a Vector2 by 100 cause rounding errors?
In my 2D project I have a character launching a projectile at a target. I want the projectile to continue until it hits a target or leaves the 'game space' and I delete it. Here is my function for moving the projectile when it gets spawned:
private Vector2 targetPosition;
private Vector2 mouseLocation;
public float moveSpeed = 5;
void Start()
{
mouseLocation = Input.mousePosition;
targetPosition = Camera.main.ScreenToWorldPoint(mouseLocation);
}
// Update is called once per frame
void Update()
{
transform.position = Vector2.MoveTowards(transform.position, targetPosition, moveSpeed * Time.deltaTime);
}
Currently the object stops when it reaches the targetPosition, but I want it to continue on it's path indefinitely (until I destroy it later).
I've tried just scaling the targetPosition vector by multiplying it by 100f but I get rounding errors like so:
void Start()
{
mouseLocation = Input.mousePosition;
targetPosition = Camera.main.ScreenToWorldPoint(mouseLocation);
Debug.Log("targetPosition: " + targetPosition.ToString("F3"));
targetPosition *= 100f;
Debug.Log("new targetPosition: " + targetPosition.ToString("F3"));
}
output:
targetPosition: (-3.485, -3.115)
new targetPosition: (-348.462, -311.539)
targetPosition: (3.254, -1.408)
new targetPosition: (325.385, -140.769)
targetPosition: (-0.469, 1.300)
new targetPosition: (-46.923, 130.000)
Am I approaching this wrong? Why is multiplying the vector giving rounding errors? Is there another way to get a vector that is a straight line between the spawn location and mouse location, but extended by a factor of 100?
Hi,
I think the issue is that Debug.log rounds vectors to one decimal point.
Try the overload option to show 3 decimal points and you should understand what is happening:
vector = new Vector3(1.234f, 5.678f, 9.012f);
Debug.Log(vector.ToString());
// unity shows (1.2, 5.7, 9.0)
// but we can show this using format - 3 numbers after the decimal point
Debug.Log(vector.ToString("F3"));
// (1.234, 5.678, 9.012)
ok cool, I'll try that as well. Thank you! In-game though, it's clear that multiplying by 100 changes the vector, by a significant amount in some cases. Once I get the debug to properly show the values, we'll be able to see exactly how far off the two vectors are.
