CODEWITHSUNDEEP
c#unity-game-engine
kredj
kredj

Reputation: 255

Quaternion Lerp not giving good results with LookRotation

I'm trying to flip my first person character smoothly while being able to rotate the player in y-axis using mouse look. The problem is the lerp does not end with an exact result. I want the ending rotation result to be exact such that (transform.up == TargetUpDirection())

void FixOrientation() {
    if(transform.up != TargetUpDirection()) //Vector3(0, -1, 0)
    {
        transform.rotation = 
            Quaternion.Lerp(transform.rotation,
                            Quaternion.LookRotation(transform.forward,
                            TargetUpDirection(), 0.1f);
    }
}

if I use mouse look while it flips, transform.up.y always result with less than 1 like for example 0.99881231 and I need to keep using mouse look until it corrects itself and I don't like it.

The cause is probably that when I use mouse look, the character forward gets modified which is causing this but I don't know how to implement a solution because quaternions confuses me.

Upvotes: 0

Views: 2065

Answers (1)

Ruzihm
Ruzihm

Reputation: 20249

It's because as written, Lerp is always rotating you 10% of the way remaining. This means that as you approach the target rotation, the amount by which you are rotated will decrease. Eventually, it will decrease to a point where rounding errors make you rotate by 0 degrees, before you actually arrive at the destination.

In most cases, you do not want to call Lerp with a constant value for t.

Here is an alternative. First, pick a maximum rotational speed:

float smooth = 5f;

Then, use Quaternion.RotateTowards:

Quaternion targetRotation = Quaternion.LookRotation(transform.forward, TargetUpDirection());
transform.rotation = Quaternion.RotateTowards(transform.rotation, targetRotation , smooth * Time.deltaTime);

This answer was based off this post on the Unity forums.

Upvotes: 3

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