Cube rotates around corners not local axis - why?

Unity Engine
1

Hello!
Sorry, this might be a newbie question since I’m very much a Unity/C# newbie.
Anyway, I can’t seem to make my cube rotate around its y axis (center) - instead, it rotates around a corner.
I also noticed my UV map is being plotted (0.5, 0.5, 0.5) away from the actual mesh - not sure if related though?

Here are the scripts I’m using for UV mapping and Dragging/Rotating the cube:

using UnityEngine;
using System.Collections;

public class ClickDrag : MonoBehaviour
{

    private float _sensitivity;
    private Vector3 _mouseReference;
    private Vector3 _mouseOffset;
    private Vector3 _rotation;
    private bool _isRotating;

    void Start ()
    {
        _sensitivity = 0.4f;
        _rotation = -(Vector3.up);
    }

    void Update()
    {
        if(_isRotating)
        {
            // offset
            _mouseOffset = (Input.mousePosition - _mouseReference);

            // apply rotation
            _rotation.y = -(_mouseOffset.x + _mouseOffset.y) * _sensitivity;

            // rotate
            transform.Rotate(_rotation);

            // store mouse
            _mouseReference = Input.mousePosition;
        }
    }

    void OnMouseDown()
    {
        // rotating flag
        _isRotating = true;

        // store mouse
        _mouseReference = Input.mousePosition;
    }

    void OnMouseUp()
    {
        // rotating flag
        _isRotating = false;
    }

}

[RequireComponent(typeof (MeshFilter))]
[RequireComponent(typeof (MeshRenderer))]
public class UVMapping : MonoBehaviour {

    void Start () {
        float size = 1f;
        Vector3[] vertices = {
            new Vector3(0, size, 0),
            new Vector3(0, 0, 0),
            new Vector3(size, size, 0),
            new Vector3(size, 0, 0),

            new Vector3(0, 0, size),
            new Vector3(size, 0, size),
            new Vector3(0, size, size),
            new Vector3(size, size, size),

            new Vector3(0, size, 0),
            new Vector3(size, size, 0),

            new Vector3(0, size, 0),
            new Vector3(0, size, size),

            new Vector3(size, size, 0),
            new Vector3(size, size, size),
        };

        int[] triangles = {
            0, 2, 1, // front
            1, 2, 3,
            4, 5, 6, // back
            5, 7, 6,
            6, 7, 8, //top
            7, 9 ,8,
            1, 3, 4, //bottom
            3, 5, 4,
            1, 11,10,// left
            1, 4, 11,
            3, 12, 5,//right
            5, 12, 13


        };


        Vector2[] uvs = {
            new Vector2(0, 0.66f),
            new Vector2(0.25f, 0.66f),
            new Vector2(0, 0.33f),
            new Vector2(0.25f, 0.33f),

            new Vector2(0.5f, 0.66f),
            new Vector2(0.5f, 0.33f),
            new Vector2(0.75f, 0.66f),
            new Vector2(0.75f, 0.33f),

            new Vector2(1, 0.66f),
            new Vector2(1, 0.33f),

            new Vector2(0.25f, 1),
            new Vector2(0.5f, 1),

            new Vector2(0.25f, 0),
            new Vector2(0.5f, 0),
        };   

        Mesh mesh = GetComponent<MeshFilter> ().mesh;
        mesh.Clear ();
        mesh.vertices = vertices;
        mesh.triangles = triangles;
        mesh.uv = uvs;
        //mesh.Optimize ();
        mesh.RecalculateNormals ();
    }
}

Any help/insight will be appreciated. :slight_smile: Thank you!

2

The defualt cube has vertex positions at (-0.5, -0.5, -0.5) and (+0.5, +0.5, +0.5) etc
you are placing them at (0,0,0) to (size, size, size) etc

result is that the pivot for the transform (0,0,0) is at one corner, instead of in the center.
the behaviour you are seeing is probably correct for the script you have written

1 Like
3

It worked! Thank you so much, hpjohn, for taking your time to help a newbie. Hope you have a great day! :slight_smile: