Unity - Subtexture Changer

/************************************************
| SubtextureChanger.cs
|
| Ian Wexler
|
| Changes the scale and offset of a material's
| texture to show a specific section.
************************************************/

using UnityEngine;

public class SubtextureChanger : MonoBehaviour
{
    [SerializeField]
    private Material material = null;

    [SerializeField]
    private int columns = 1;

    [SerializeField]
    private int rows = 1;

    [SerializeField]
    private int index = 0;

    private void OnValidate()
    {
        SetSubtexture(index);
    }

    public void SetSubtexture(int i)
    {
        // Loop around and filter out negative values.
        int count = columns * rows;
        index = (i % count + count) % count;

        Vector2 offset = new Vector2();
        Vector2 scale = new Vector2();

        // Set the scale based on rows and columns.
        scale.x = 1 / (float)columns;
        scale.y = 1 / (float)rows;

        // Set the offset so the index increases on x and then y.
        offset.x = (index % columns) * scale.x;
        offset.y = (index / columns) * scale.y;

        // Apply the scale and offset.
        material.SetTextureScale("_MainTex", scale);
        material.SetTextureOffset("_MainTex", offset);
    }
}