unity 顶点弹性网格效果

1.球衰减

首先，我们将处理球衰减,鼠标或手指点中网格的点是碰撞点，越往外它所受的影响越小。我们需要从CPU中获取“_ImpactPos”这个碰撞点，获取摄像机和碰撞点的矢量，我们将对我们网格的每个顶点执行相对于撞击点的球面衰减。

DeformableActor.shader

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void vert(inout appdata v) {     float3 dst = _ImpactPos - v.vertex.xyz;     dst.x = dot(dst, dst) / _Radius;     float attenuation = 1 / (1 + dst.x);         // To Do }

2.反弹效应

　　在CPU里，我们用AnimationCurve手动调好一个正弦曲线，衰减随着时间的推移，以获得预期的效果(见图2.1)。

图2.1.指数阻尼正弦波（也可以自己在代码里写阻尼公式）

public class DeformableActor : MonoBehaviour
{
    [SerializeField]
    private float maxScale = 3f;

    [SerializeField]
    private float duration = 1f;

    [SerializeField]
    private AnimationCurve curve;

    private Camera mainCamera;

    private Material dynamicMat;

    private bool bIsBouncing;

    private float timer;

    private Vector3 direction,
        dampingVector;

    // Use this for initialization
    private void Start()
    {
        mainCamera = Camera.main;
        dynamicMat = GetComponent<MeshRenderer>().material;
    }

    // Update is called once per frame
    private void Update()
    {
        if (bIsBouncing)
            BounceActor();

        if (!Input.GetMouseButton(0))
            return;

        DoRayCasting();
    }

    // ---------------------
    private void OnDestroy()
    {
        Destroy(dynamicMat);
    }

    // -------------------------------------------------------------
    private void BounceActor()
    {
        timer += Time.deltaTime / duration;

        if (timer <= 1f)
        {
            dampingVector = curve.Evaluate(timer)
                * maxScale * direction;

            dynamicMat.SetVector("_DampingVector", dampingVector);
        }
        else
        {
            bIsBouncing = false;
            dynamicMat.SetVector("_DampingVector", Vector3.zero);
        }
    }

    // ------------------------------------------------------------------
    private void DoRayCasting()
    {
        RaycastHit hit = new RaycastHit();

        if (Physics.Raycast(mainCamera
            .ScreenPointToRay(Input.mousePosition), out hit))
        {
            dynamicMat.SetVector("_ImpactPos",
                transform.InverseTransformPoint(hit.point));

            direction = (mainCamera.transform.position
                - hit.point).normalized;
            direction = transform.InverseTransformDirection(direction);

            bIsBouncing = true;
            timer = 0f;
        }
    }
}

3.关于网格顶点变形的shader

Shader "FI/DeformableActor" {
    Properties{
        _Radius("Radius", Float) = 1
        _Color("Color", Color) = (1,1,1,1)
        _MainTex("Albedo (RGB)", 2D) = "white" {}
        _Normal("Normal", 2D) = "bump" {}
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
    }
    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200

        Cull Off

        CGPROGRAM

        #pragma surface surf Standard fullforwardshadows vertex:vert addshadow //在surface shader中想要进行顶点偏移，要加上vertex:vert
        #pragma target 3.0

        #include "UnityCG.cginc"

        struct appdata {
            float4 vertex : POSITION;
            float4 tangent : TANGENT;
            float3 normal : NORMAL;
            float2 texcoord : TEXCOORD0;
        };

        sampler2D _MainTex;
        sampler2D _Normal;

        half _Glossiness;
        half _Metallic;
        fixed4 _Color;

        float _Radius;
        float3 _DampingVector;
        float3 _ImpactPos;

        struct Input {
            float2 uv_MainTex;
        };

        void vert(inout appdata v) {
            float3 dst = _ImpactPos - v.vertex.xyz;
            dst.x = dot(dst, dst) / _Radius;
            float attenuation = 1 / (1 + dst.x); //离hit的点越远的顶点得到的attenuation的值越小，即顶点的晃动就会越小
            v.vertex.xyz += _DampingVector * attenuation;
        }

        UNITY_INSTANCING_BUFFER_START(Props)

        UNITY_INSTANCING_BUFFER_END(Props)

        void surf (Input IN, inout SurfaceOutputStandard o) {
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
            o.Albedo = c.rgb;
            o.Normal = UnpackNormal(tex2D(_Normal, IN.uv_MainTex));
            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}

类似的例子（心脏的跳动）：https://blog.csdn.net/u010133610/article/details/51863887