unity 波浪（一） 正弦波

目标：

需要实现通过改变mesh的顶点坐标来实现面片类似海浪一样的流动。

两个方案：shader或者脚本做顶点坐标修改

在unity中创建表面shader

k = 2π/wavelength  ,wavelength 是 波长 

正弦波   y = 振幅 * sin(k * x )

流动偏移  y = 振幅 * sin(k * ( x - 速度 * 时长))

---------------------------------------------------正弦到这其实就可以了，形就有了

接收阴影，就需要设置法线

求导： (sinf)' = f' * cos f

 f = k * ( x - 速度 * 时长),这块看做一个整体，y = a * sin f ,那(y)' = (a * sing f)'

推出 = a * k * cos f

完整shader：

Shader "MyShader/Waves"
{
    Properties
    {
        _Color ("Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
        _Amplitude("Amplitude", float) = 1
        _Wavelength("Wavelength", float) = 10
        _Speed ("Speed", float) = 1
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 200

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        //addshadow :接受阴影  vertex:vert 顶点坐标
        #pragma surface surf Standard fullforwardshadows vertex:vert addshadow

        // Use shader model 3.0 target, to get nicer looking lighting
        #pragma target 3.0


        sampler2D _MainTex;

        struct Input
        {
            float2 uv_MainTex;
        };

        half _Glossiness;
        half _Metallic;
        fixed4 _Color;
        float _Amplitude,_Wavelength, _Speed;

        // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
        // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
        // #pragma instancing_options assumeuniformscaling
        UNITY_INSTANCING_BUFFER_START(Props)
            // put more per-instance properties here
        UNITY_INSTANCING_BUFFER_END(Props)

        void surf (Input IN, inout SurfaceOutputStandard o)
        {
            // Albedo comes from a texture tinted by color
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
            o.Albedo = c.rgb;
            // Metallic and smoothness come from slider variables
            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
            o.Alpha = c.a;
        }

        void vert(inout appdata_full vertexData)
        {
            float3 p = vertexData.vertex.xyz;
           
            float k = 2 * UNITY_PI /_Wavelength;
            float f = k * (p.x - _Speed * _Time.y);

            // p.y = _Amplitude * sin(k * (p.x - _Speed * _Time.y));
            p.y = _Amplitude * sin(f);

            float3 tangent = normalize(float3(1,k*_Amplitude * cos(f),0));//法线
            float3 normal = float3(-tangent.y,tangent.x,0);
          
            vertexData.vertex.xyz = p;
            vertexData.normal = normal;
        }
        ENDCG
    }
    FallBack "Diffuse"
}

通过脚本做顶点坐标修改

代码备份

using System;
using UnityEngine;

public class Test : MonoBehaviour
{
    public MeshFilter m_TargetMeshFilter = null;
    private Mesh m_TargetMesh = null;
    public float A = 2;//振幅
    public float speed = 1;//水流速度
    public float wavelength = 10;//波长

    private Vector3[] baseVertices;//顶点坐标

    private void Start()
    {
        m_TargetMesh = m_TargetMeshFilter.mesh;
        baseVertices = m_TargetMesh.vertices;
    }
    private void Update()
    {
        if (m_TargetMesh != null)
        {
            Vector3[] temp = m_TargetMesh.vertices;
            for (int i = 0; i < temp.Length; i++)
            {
                Vector3 target = temp[i];
                Vector3 v = baseVertices[i];

                float k = 2 * Mathf.PI / wavelength;
                target.y = A * (float)Math.Sin(k * (v.x - speed * Time.fixedTime));

                temp[i] = new Vector3(target.x, target.y, target.z);

                Debug.Log(target);

            }
            m_TargetMesh.vertices = temp;
            // 重新计算Mesh的法线和边界
            m_TargetMesh.RecalculateNormals();
            m_TargetMesh.RecalculateBounds();
        }

    }
}