using System.Collections.Generic;
using UnityEngine;

public class WorldUvMapper : UvMapper
{
    /// <summary>
    /// Determines the scale to be applied to the uv-coordinates. (1,1) will repeat the texture once for every local-space unit, (2,2) twice and so on.
    /// </summary>
    public Vector2 scale = Vector2.one;

    public override void Map(IList<Vector3> points, Vector3 planeNormal, out Vector4[] tangentsA, out Vector4[] tangentsB, out Vector2[] uvsA, out Vector2[] uvsB)
    {
        // Calculate texture direction vectors
        Vector3 u = Vector3.Cross(planeNormal, Vector3.up);

        if (u == Vector3.zero)
        {
            u = Vector3.Cross(planeNormal, Vector3.forward);
        }

        Vector3 v = Vector3.Cross(u, planeNormal);

        u.Normalize();
        v.Normalize();

        // Set tangents
        Vector4 tangentA = new Vector4(u.x, u.y, u.z, 1.0f);
        Vector4 tangentB = new Vector4(u.x, u.y, u.z, -1.0f);

        tangentsA = new Vector4[points.Count];
        tangentsB = new Vector4[points.Count];

        for (int i = 0; i < points.Count; i++)
        {
            tangentsA[i] = tangentA;
            tangentsB[i] = tangentB;
        }

        // Set uvs
        Vector2[] uvs = new Vector2[points.Count];

        Vector2 min = Vector2.zero;

        for (int i = 0; i < points.Count; i++)
        {
            Vector3 point = points[i];

            uvs[i].x = Vector3.Dot(point, u);
            uvs[i].y = Vector3.Dot(point, v);

            if (i == 0)
            {
                min = uvs[i];
            }
            else
            {
                min = Vector2.Min(uvs[i], min);
            }
        }

        for (int i = 0; i < points.Count; i++)
        {
            uvs[i] -= min;

            uvs[i].x *= scale.x;
            uvs[i].y *= scale.y;
        }

        uvsA = uvs;
        uvsB = uvs;
    }
}