Set new forward directions based on camera position [duplicate]

Question

I have a 3rd person camera which can rotate around the player.

When I look at the back of the player and press forward, player goes forward. Then I rotate 360 around the player and "forward direction" is tilted for 90 degrees. So every 360 turn there is 90 degrees of direction change.

For example when camera is facing the right side of the player, when I press button to move forward, I want player to turn to the left and make that the "new forward".

I have Player object with Camera as child object. Camera object has Camera script. Inside Camera script there are Player and Camera classes. Player object itself, has Input Controller.

Also I'm making this script for joystick/ controller primarily.

My camera script so far:

using UnityEngine;
using System.Collections;

public class CameraScript : MonoBehaviour
{
    public GameObject Target;
    public float RotateSpeed = 10,
    FollowDistance = 20,
    FollowHeight = 10;
    float RotateSpeedPerTime,
    DesiredRotationAngle,
    DesiredHeight,
    CurrentRotationAngle,
    CurrentHeight,
    Yaw,
    Pitch;
    Quaternion CurrentRotation;

    void LateUpdate()
    {
        RotateSpeedPerTime = RotateSpeed * Time.deltaTime;

        DesiredRotationAngle = Target.transform.eulerAngles.y;
        DesiredHeight = Target.transform.position.y + FollowHeight;
        CurrentRotationAngle = transform.eulerAngles.y;
        CurrentHeight = transform.position.y;

        CurrentRotationAngle = Mathf.LerpAngle(CurrentRotationAngle, DesiredRotationAngle, 0);
        CurrentHeight = Mathf.Lerp(CurrentHeight, DesiredHeight, 0);

        CurrentRotation = Quaternion.Euler(0, CurrentRotationAngle, 0);
        transform.position = Target.transform.position;
        transform.position -= CurrentRotation * Vector3.forward * FollowDistance;
        transform.position = new Vector3(transform.position.x, CurrentHeight, transform.position.z);

        Yaw = Input.GetAxis("Right Horizontal") * RotateSpeedPerTime;
        Pitch = Input.GetAxis("Right Vertical") * RotateSpeedPerTime;
        transform.Translate(new Vector3(Yaw, -Pitch, 0));
        transform.position = new Vector3(transform.position.x, transform.position.y, transform.position.z);

        transform.LookAt(Target.transform);
    }
}

My player script:

using UnityEngine;
using System.Collections;

public class PlayerScript : MonoBehaviour
{
    public float RotateSpeed = 10,
    MoveSpeed = 10;
    float DeltaTime;
    public Transform cameraTransform;

    void Update()
    {
        DeltaTime = Time.deltaTime;
        transform.Rotate(0, Input.GetAxis("Right Horizontal") * RotateSpeed * DeltaTime, 0);
    }
}

Answer 1

If the player is looking directly at the camera we can use the following idea to find the direction the player should walk, based on the position of the camera.

We have two vectors C: (camera.Transform.Forward) the direction the camera is looking at and P (player.Transform.Forward) the direction the player is looking at.

By computing the acos of the dot product of these two vectors we can compute the angle between these to vectors.

angle = acos(dot(C, P);

This angle can be used to rate the player so that it faces the camera (just rotate the player by -angle) and it can be used to transform controller inputs so that no matter where the camera and player is 'left' will always be left as seen from the camera.

This can be done by constructing the left, forward, right, and backward vectors like this.

// Assumes the forward vector normally is (0, 0, 1) or
// (cos(pi/2 + 0), 0, sin(pi/2 + 0))   
vector3 forward = (cos(pi/2) + angle), 0, sin(pi /2 + angle);

If you wish the player to face the forward vector, or another vector you can again compute the acos of the dot product between that vector and the vector that points to where the player is currently facing. Just rotate the player by minus the result of that computation.

There might be small math errors in this answer (offsets wrong by half a pi, a minus that should or shouldn't be there) but I hope the general idea is now quite clear and that you can deduce the other direction vectors yourself.

Answer 2

I shall rephrase, the direction the player is facing is the forward direction, Therefor the camera should face forward (i.e the direction the player is facing), so the camera should be aimed at the player location always (unless you choose it to follow a different object like a vehicle) so there fore the camera facing point is player.location (This isn't code just variables for vectors)

     Camera.facing =player.facing; /*this makes the camera face the way the player is facing...therefor camera will always face forward,( i.e the direction the player is facing...)rotating the player 360 degrees should place the camera back where it started (behind the player facing the way the player is facing) rotating it 180 degrees should place the camera still behind the player but but moved on the yaw to face the same way the player is now facing,the idea is not to make a whole new purpose of a "new forward" variable but use a variable that's already there....*/

     Camera.facing=player.location; //*his makes the camera face the location of your player which means the camera might not be facing where the player is facing but more at where he is, this method will allow you too see the front of the player if he is facing the camera, and the back if he is not,or his sides if he is moving that way (this method sounds like the one you need ;) ) */
     Camera.location=player.location.z-4&&player.location.y+2; /*this simply places the camera behind the player at all times (you can change this if you want...)

It also sounds like you don't understand this "player.location.x" (this is a vector player.location.x refers to the x piece of the vector where as player.location.y refers to the y piece of the vector and player.location.z refers to the z piece of the vector.... Understanding that should allow you to properly place the camera and view angle correctly, but I do want you to know that rotating 360 degrees should place the camera in the exact place it was... Feel free to ask more questions to me if you don't understand :) Hope this Helps :) Good Luck :)