Unity 大地图高性能砍树顶点动画Shader

当前方案适合：类饥荒2d生存类大量的树动画

前言

在大地图中成千上万的树不可能给每一个树都用Spine来做，所以本文章分享了一种通过shader来实现的方案

在一些大的开放世界中会用静态模型LOD+shader+动态替换被砍的那棵树来做动画但是今天我们只讲在移动端如何去处理大量的数

脚本中我用了MaterialPropertyBlock处理不会打断合批同时还能修改单个对象的属性

csharp 复制代码

using UnityEngine;

[DisallowMultipleComponent]
public class TreeHitFx : MonoBehaviour
{

    static readonly int ID_HitTime = Shader.PropertyToID( "_HitTime" );
    static readonly int ID_HitAmp = Shader.PropertyToID( "_HitAmp" );
    const float FORCE = 3f;

    SpriteRenderer sr;
    MaterialPropertyBlock mpb;
    private Vector3 CachePos = Vector3.zero;

    public void Init( Vector3 Pos, SpriteRenderer icon )
    {
        CachePos = Pos;

        sr = icon;
        mpb = new MaterialPropertyBlock( );
        Clear( );
    }

    public void Clear( )
    {
        if ( null != mpb )
        {
            sr.GetPropertyBlock( mpb );
            mpb.SetFloat( ID_HitTime, 0f );
            mpb.SetFloat( ID_HitAmp, 0f );
            sr.SetPropertyBlock( mpb );
        }
    }

    /// <summary>
    /// 播放受击动画
    /// </summary>
    /// <param name="worldHitPos">砍中点 (世界坐标)</param>
    public void PlayHit( Vector2 worldHitPos )
    {
        sr.GetPropertyBlock( mpb );
        mpb.SetFloat( ID_HitTime, Time.time );
        mpb.SetFloat( ID_HitAmp, worldHitPos.x - CachePos.x > 0f ? FORCE : -FORCE );
        sr.SetPropertyBlock( mpb );
    }

}

c 复制代码

Shader "Custom/Sprite_TreeHit"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
        
        _HitTime ("Hit Time", Float) = -100
        _HitAmp ("Hit Amplitude", Float) = 0.5
        _HitFreq ("Hit Frequency", Float) = 15
        _HitDamp ("Hit Damping", Float) = 3
        _FlashColor ("Flash Color", Color) = (1,1,1,1)
        _FlashDuration ("Flash Duration", Float) = 0.1
    }

    SubShader
    {
        Tags
        { 
            "Queue"="Transparent" 
            "IgnoreProjector"="True" 
            "RenderType"="Transparent" 
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Cull Off
        Lighting Off
        ZWrite Off
        Blend One OneMinusSrcAlpha

        Pass
        {
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile _ PIXELSNAP_ON
            #include "UnityCG.cginc"

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord : TEXCOORD0;

                fixed flashFactor : TEXCOORD1; 
            };

            fixed4 _Color;
            float _HitTime;
            float _HitAmp;
            float _HitFreq;
            float _HitDamp;
            fixed4 _FlashColor;
            float _FlashDuration;

            v2f vert(appdata_t IN)
            {
                v2f OUT;
                
                float t = _Time.y - _HitTime;
                float isValidTime = step(0, t) * step(t, 5.0);
                
                float decay = exp(-t * _HitDamp);
                float wave = decay * sin(t * _HitFreq);
                float bend = wave * _HitAmp * IN.texcoord.y * IN.texcoord.y * isValidTime;
                IN.vertex.x += bend;

                OUT.vertex = UnityObjectToClipPos(IN.vertex);
                OUT.texcoord = IN.texcoord;
                OUT.color = IN.color * _Color;
                float flashProgress = t / _FlashDuration;
                OUT.flashFactor = saturate(1.0 - flashProgress) * step(0, t);
                
                #ifdef PIXELSNAP_ON
                OUT.vertex = UnityPixelSnap (OUT.vertex);
                #endif

                return OUT;
            }

            sampler2D _MainTex;

            fixed4 frag(v2f IN) : SV_Target
            {
                fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
                
                c.rgb *= c.a;
                c.rgb += _FlashColor.rgb * IN.flashFactor * c.a;
                return c;
            }
        ENDCG
        }
    }
}

补充

关于这个树是如何通过定点来实现摇摆动画的，其实很多文章都有哈，原理和草是一样的，鄙人有一点懒就不赘述了如果想学习原理的可以查一下类似草shader相关就出来了哈