using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SpriteAnim : MonoBehaviour
{
    public int uvAnimationTileX = 10; //Here you can place the number of columns of your sheet. 
    public int uvAnimationTileY = 8; //Here you can place the number of rows of your sheet. 
    public float framesPerSecond = 10.0f;
    public string ColorTexName = "_BaseMap";
    public string EmissiveTexName = "_EmissiveMap";
    public bool useEmissive = false;
    private int colorTexID = -1;
    private int emissiveTexID = -1;
    Material mat;
    // Start is called before the first frame update
    void Start()
    {
        mat = GetComponent<Renderer>().material;
        if (mat)
        {
            colorTexID = Shader.PropertyToID(ColorTexName);
            emissiveTexID = Shader.PropertyToID(EmissiveTexName);
        }

        if (!mat.HasProperty(colorTexID))
        {
            Debug.LogError("Shader property not found: " + ColorTexName);
            enabled = false;
        }

        if (useEmissive && !mat.HasProperty(emissiveTexID))
        {
            Debug.LogError("Shader property not found: " + EmissiveTexName);
            enabled = false;

        }
    }

    // Update is called once per frame
    void Update()
    {
        // Calculate index
        int index = (int)(Time.time * framesPerSecond);
        // repeat when exhausting all frames
        index = index % (uvAnimationTileX * uvAnimationTileY);

        // Size of every tile
        var size = new Vector2(1.0f / uvAnimationTileX, 1.0f / uvAnimationTileY);

        // split into horizontal and vertical index
        var uIndex = index % uvAnimationTileX;
        var vIndex = index / uvAnimationTileX;

        // build offset
        // v coordinate is the bottom of the image in opengl so we need to invert.
        var offset = new Vector2(uIndex * size.x, 1.0f - size.y - vIndex * size.y);

        mat.SetTextureOffset(colorTexID, offset);
        mat.SetTextureScale(colorTexID, size);

        if (useEmissive)
        {
            mat.SetTextureOffset(emissiveTexID, offset);
            mat.SetTextureScale(emissiveTexID, size);
        }
    }
}