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

namespace Utility.Meshes
{

    public static class Curve
    {

        // Could do this on the GPU
        public static Vector3[] CurveVertices(Vector3[] vertices, Vector3 ringCentre, Vector3 Axis, Transform origin, Vector3 meshCentre)
        {
            Vector3[] curvedVertices = new Vector3[vertices.Length];
            Vector3 down = Vector3.ProjectOnPlane(meshCentre - ringCentre, Axis).normalized;
            Vector3 perpendicular = Vector3.Cross(Axis, down).normalized;
            float radius = Vector3.ProjectOnPlane(meshCentre - ringCentre, Axis).magnitude;

            for (int i = 0; i < vertices.Length; i++)
            {
                Vector3 position = origin.TransformPoint(vertices[i]);
                Vector3 directionFromCentre = Vector3.Project(position - meshCentre, perpendicular);
                Vector3 directionAlongAxis = Vector3.Project(position - ringCentre, Axis);
                float vertexRadius = Vector3.Project(position - ringCentre, down).magnitude;

                float arcLength = directionFromCentre.magnitude;
                float angle = (arcLength / radius);
                if (Vector3.Dot(directionFromCentre, perpendicular) < 0)
                    angle = -angle;

                Vector3 curvedDirection = Quaternion.AngleAxis(Mathf.Rad2Deg * angle, Axis) * down;
                curvedVertices[i] = origin.InverseTransformPoint(ringCentre + (curvedDirection.normalized * (vertexRadius)) + directionAlongAxis);
            }

            return curvedVertices;
        }

    }
}