OldBlueWater/BlueWater/Assets/02.Scripts/WaterAndFloater/Gerstner wave/GerstnerWave.cs

using Sirenix.OdinInspector;
using UnityEngine;

// ReSharper disable once CheckNamespace
namespace BlueWaterProject
{
    public class GerstnerWave : MonoBehaviour
    {
        [InfoBox("파도의 길이를 결정, 값이 클수록 파도 간의 간격이 커짐")]
        public float waveLength = 0.1f;
        [InfoBox("파도의 높이를 결정, 값이 클수록 파도의 높이가 커짐")]
        public float amplitude = 0.1f;
        [InfoBox("파도의 속도를 결정, 값이 클수록 파도의 속도가 오름")]
        public float speed = 1f;
        [InfoBox("파도의 방향을 결정")]
        public Vector2 direction = new Vector2(1.0f, 0.0f);

        private void FixedUpdate()
        {
            var mesh = GetComponent<MeshFilter>().mesh;
            var vertices = mesh.vertices;
            var normals = mesh.normals;

            var waveNumber = 2.0f * Mathf.PI / waveLength;
            var phaseConstant = speed * waveNumber;

            for (var i = 0; i < vertices.Length; i++)
            {
                var vertex = vertices[i];
                var dotProduct = Vector2.Dot(new Vector2(vertex.x, vertex.z), direction);
                var wavePhase = waveNumber * dotProduct + phaseConstant * Time.time;
                vertex.y = amplitude * Mathf.Sin(wavePhase);
                vertices[i] = vertex;

                // Calculate the normal at the vertex
                var cosPhase = Mathf.Cos(wavePhase);
                var dx = -waveNumber * amplitude * direction.x * cosPhase;
                var dz = -waveNumber * amplitude * direction.y * cosPhase;
                normals[i] = new Vector3(dx, 1.0f, dz).normalized;
            }

            mesh.vertices = vertices;
            mesh.normals = normals;
        }

        public Vector3 GetWaveNormal(Vector3 position)
        {
            var waveNumber = 2.0f * Mathf.PI / waveLength;
            var phaseConstant = speed * waveNumber;
            var dotProduct = Vector2.Dot(new Vector2(position.x + transform.position.x, position.z + transform.position.z), direction);
            var wavePhase = waveNumber * dotProduct + phaseConstant * Time.time;

            var cosPhase = Mathf.Cos(wavePhase);

            // We differentiate the wave function to get the slope at the current point
            var dx = -waveNumber * amplitude * direction.x * cosPhase;
            var dz = -waveNumber * amplitude * direction.y * cosPhase;

            var normal = new Vector3(dx, 1.0f, dz).normalized;
            return normal;
        }
    }
}