Camera used Quaternion.Lerp or Slerp to Rotate can't work well when t is not 1

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1

I use mouse LeftButton to rotate camera. But when I run the program, I find that if Quaternion.Lerp(loaclRotation, newRotation, t) t !=1, the camera.transform.localRotation and parent.transform will not equal to xR and yR. After rotating, if clicked mouse leftbutton, camera will rotate a little angle.
I think the reason will be that when t < 1 , the final rotation not equal xR or yR.so when I clicked , it will execute Quaternion.Lerp again, until the camera.localRotation equal xR or yR.

I make the t value is 1, so the Camera localRotation will be equal to xR or yR.
Is there any other solution to solve this problem?

`

if ((mouseState == MouseState.None ||mouseState == MouseState.LeftMouseBtn) && mouseLeftDown) {
            float mouseX = Input.GetAxis("Mouse X");
            float mouseY = Input.GetAxis("Mouse Y");
            smoothMouseX = mouseX;
            smoothMouseY = mouseY;

        
        var x = smoothMouseX * xRSpeed * Time.deltaTime;
        var y = smoothMouseY * yRSpeed * Time.deltaTime;

        xR -= x ;
        yR += y ;
        //Debug.Log("xR:" + xR + "yR:" + yR);
        xR = ClampValue(xR, -360, 360);
        yR = ClampValue(yR, yRMin, yRMax);

        var rotation_x = Quaternion.Euler(yR, 0, 0);
        var rotation_y = Quaternion.Euler(0, xR, 0);

        //camera's parent component rotate the Y    
        transform.localRotation = Quaternion.Lerp(transform.localRotation, rotation_y , 1f);
        //camera transform rotate the X

        camera.transform.localRotation = Quaternion.Lerp(camera.transform.localRotation, rotation_x, 1f);

`

2

Hi @Jaquior_qiao ,

you problem exist because Quaternion.Lerp is called only when (mouseState == MouseState.None ||mouseState == MouseState.LeftMouseBtn) && mouseLeftDown)…
so in order to achieve position t needs to be 1.

but if you change approach, maybe you will get expected result, so you will need to cache Quaternions outside of Update:

Quaternion m_parentDesiredQuaternion;
Quaternion m_cameraDesiredQuaternion;

    void Update()
    {
        if (( mouseState == MouseState.LeftMouseBtn) && mouseLeftDown)
        {
            float mouseX = Input.GetAxis("Mouse X");
            float mouseY = Input.GetAxis("Mouse Y");
            smoothMouseX = mouseX;
            smoothMouseY = mouseY;


            var x = smoothMouseX * xRSpeed * Time.deltaTime;
            var y = smoothMouseY * yRSpeed * Time.deltaTime;

            xR -= x;
            yR += y;

            xR = ClampValue(xR, -360, 360);
            yR = ClampValue(yR, yRMin, yRMax);

            m_cameraDesiredQuaternion = Quaternion.Euler(yR, 0, 0);
            m_parentDesiredQuaternion = Quaternion.Euler(0, xR, 0);
        }

        //camera's parent component rotate the Y    
        transform.localRotation = Quaternion.Lerp(transform.localRotation, m_parentDesiredQuaternion, .3f);
        //camera transform rotate the X
        camera.transform.localRotation = Quaternion.Lerp(camera.transform.localRotation, m_cameraDesiredQuaternion, .3f);
    }

so Lerp is called outside of If Mouse Input Check, and values like .3f instead of 1, can make sense…

Hope will do! Let me know how it went.

3

thank you very much! It works. I should update the Rotation Quaternion in If sentence, and update the camera Rotation out of it. Then the Camera will set the right Rotation. :smiling_face_with_three_hearts:

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