unity - camera movement

Question

I'm reviewing this piece of code about camera movement:

 using UnityEngine;
 using System.Collections;

 public class CamMove : MonoBehaviour {
    Vector2 mouseLook;
    Vector2 smoothV;
    public float sensitivity=5.0f;
    public float smoothing = 2.0f;

    GameObject character;
    void Start()
    {
        //moving left and right
        character = this.transform.parent.gameObject;
    }

    void Update()
    {
        var md = new Vector2 (Input.GetAxisRaw ("Mouse X"), Input.GetAxisRaw ("Mouse Y")); //mouse movement
        md = Vector2.Scale (md, new Vector2 (sensitivity * smoothing, sensitivity * smoothing));
        smoothV.x = Mathf.Lerp (smoothV.x, md.x, 1f / smoothing);



        smoothV.y = Mathf.Lerp (smoothV.y, md.y, 1f / smoothing);

        mouseLook += smoothV;
        if(mouseLook.y>-40 && mouseLook.y<60)
                    transform.localRotation = Quaternion.AngleAxis (-mouseLook.y, Vector3.right);

        character.GetComponent<CharacterController>().transform.localRotation = Quaternion.AngleAxis (mouseLook.x, character.transform.up);
    }


 }

how does he get every new locatiion ? With Math.Lerp interpolation ? Also I can't understand the part md = Vector2.Scale (md, new Vector2 (sensitivity * smoothing, sensitivity * smoothing)); Also the part :

if(mouseLook.y>-40 && mouseLook.y<60)
                    transform.localRotation = Quaternion.AngleAxis (-mouseLook.y, Vector3.right);

When in doubt, follow the code.. if you dont understand what it does, look up the unity calls, print out the values... and watch and see what happens — BugFinder
– BugFinder, Commented Jan 11, 2020 at 12:58
All the code does is move the camera left and right when called using the mouse position. It is only looking at the Y range -40 to 60. — jdweng
– jdweng, Commented Jan 11, 2020 at 13:40

derHugo · Accepted Answer · 2020-01-11 14:41:02Z

Well

var md = new Vector2 (Input.GetAxisRaw ("Mouse X"), Input.GetAxisRaw ("Mouse Y")); //mouse movement

is even commented mouse movement. As usual a better variable name would already explain it. It would be better called mouseDelta. So the code not using a fixed mouse position but rather the traveled dinstance since last frame. (See Input.GetRawAxis)

Then

md = Vector2.Scale (md, new Vector2 (sensitivity * smoothing, sensitivity * smoothing));

Vector2.Scale is scaling up or down this Vector. You could also write it as

md = new Vector2 (md.x * sensitivity * smoothing, md.y * sensitivity * smoothing);

Actually it is quite unnecessary because you could write it way simplier like this:

md *= sensitivity * smoothing;

Then Mathf.Lerp is a linear interpolation between the two given positions using a certain factor between 0 and 1, where 0 would be fully the first parameter, 1 fully the second, otherwise anything in between. E.g. a factor 0.5 would result in the center between both values so this depends on your given value for smoothing

    smoothV.x = Mathf.Lerp (smoothV.x, md.x, 1f / smoothing);
    smoothV.y = Mathf.Lerp (smoothV.y, md.y, 1f / smoothing);

Again this is written quite unnecessarily because it is better written directly using Vector2.Lerp

 smoothV = Vector2.Lerp(smoothV, md, 1f/smoothing);

But actually I'm not quite sure this even does what you would expect since this is no absolute value but something you later on add every frame so using a Lerp on it makes not much sense to me anyway... I would probably directly use Lerp for moving the current mouseLoock towards the new target value.

Finally you do

mouseLook += smoothV;
if(mouseLook.y>-40 && mouseLook.y<60)
    transform.localRotation = Quaternion.AngleAxis (-mouseLook.y, Vector3.right);

character.GetComponent<CharacterController>().transform.localRotation = Quaternion.AngleAxis (mouseLook.x, character.transform.up);

Which updates two rotations. There is nothing in your code assigning any new position at all ...

Besides that the frame wise usage of GetComponent is extremely inefficient, you should rather store that reference once (e.g. in Start) and reuse it later.

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