1

I’m trying to rotate a vector relative to a transform.position by using Quaternion.Euler() with an angle. It works when the transform.position is (0, 0, 0), but when I change the transform.position to (0, 0, 1) I get unexpected results.

Here’s my code and screens:

61701-capture-good.png

61702-capture-bad.png

using UnityEngine;
using System.Collections;

public class RotateTest1 : MonoBehaviour
{
    float offset = 3.5f;

    void Update()
    {
        DrawReferenceLines();
        DrawAngleLines();
    }

    private void DrawAngleLines()
    {
        // Gives expected rotation
        //transform.position = new Vector3(0, 0, 0);

        // Gives unexpected rotation
        transform.position = new Vector3(0, 0, 1);

        Vector3 pos = transform.position;

        Vector3 direction = new Vector3(pos.x, pos.y, pos.z - offset);

        // draw original line
        Debug.DrawLine(pos, direction, Color.cyan);

        float angle = 45f;
        direction = Quaternion.Euler(0, angle, 0) * direction;

        // draw rotated line
        Debug.DrawLine(pos, direction, Color.magenta);

        Debug.Log(string.Format("direction: {0}", direction));
    }

    private void DrawReferenceLines()
    {
        Vector3 pos = transform.position;

        Vector3 left = pos + new Vector3(pos.x + offset, pos.y, pos.z);
        Vector3 right = pos + new Vector3(pos.x - offset, pos.y, pos.z);
        Vector3 front = pos + new Vector3(pos.x, pos.y, pos.z + offset);
        Vector3 back = pos + new Vector3(pos.x, pos.y, pos.z - offset);

        Debug.DrawLine(pos, left - pos);
        Debug.DrawLine(pos, right - pos);
        Debug.DrawLine(pos, front - pos);
        Debug.DrawLine(pos, back - pos);
    }
}
2

Welp, fixed my issue. I suppose it’s what you’re supposed to do. :slight_smile:

61767-capture.png

using UnityEngine;
using System.Collections;

public class RotateTest2 : MonoBehaviour
{
    float offset = 3.5f;

    void Update()
    {
        // Get initial direction
        Vector3 direction = new Vector3(0, 0, -offset);

        // draw initial line
        Debug.DrawLine(transform.position, transform.position + direction, Color.cyan);

        // rotate the crap out of this direction :)
        for (float angle = 10f; angle < 360; angle = angle + 10f)
        {
            // apply rotation to direction
            Vector3 rotatedDirection = Quaternion.Euler(0, angle, 0) * direction;

            // draw rotated line
            Debug.DrawLine(transform.position, transform.position + rotatedDirection, Color.magenta);
        }
    }
}