上面这个脚本报错：undeclaredidentifier”_AmbientColor"

抱歉，这是因为在上面修改的代码片段中，_AmbientColor变量也没有定义。你可以尝试在Properties块中添加_AmbientColor属性，然后在Pass块的frag函数中使用UnityGlobalAmbientColor来获取Unity的全局环境光颜色。

以下是修改过的Shader代码：

Shader "Custom/URPHighLight" {
    Properties {
        _Color ("Color", Color) = (1,1,1,1)
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _BumpMap ("Normal Map", 2D) = "bump" {}
        _HighLightColor ("HighLight Color", Color) = (1,1,1,1)
        _HighLightIntensity ("HighLight Intensity", Range(0,1)) = 0.2
        _HighLightSpeed ("HighLight Speed", Range(0,1)) = 0.2
        _AmbientColor ("Ambient Color", Color) = (1,1,1,1)
    }
 
    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 100
 
        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
 
            #include "UnityCG.cginc"
 
            struct appdata {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float2 uv : TEXCOORD0;
            };
 
            struct v2f {
                float2 uv : TEXCOORD0;
                float3 worldNormal : TEXCOORD1;
                float3 worldPos : TEXCOORD2;
                UNITY_FOG_COORDS(3)
                float4 vertex : SV_POSITION;
            };
 
            sampler2D _MainTex;
            sampler2D _BumpMap;
            float4 _Color;
            float _Glossiness;
            float _Metallic;
            float4 _HighLightColor;
            float _HighLightIntensity;
            float _HighLightSpeed;
            float4 _AmbientColor;
 
            v2f vert (appdata v) {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.worldNormal = UnityObjectToWorldNormal(v.normal);
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
                o.uv = v.uv;
                UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
            }
 
            fixed4 frag (v2f i) : SV_Target {
                // calculate lighting
                float3 worldNormal = normalize(i.worldNormal);
                float3 worldPos = i.worldPos;
                float3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz - worldPos);
                float3 albedo = tex2D(_MainTex, i.uv).rgb * _Color.rgb;
                float3 specular = _HighLightColor.rgb * _HighLightIntensity;
                float3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));
                float3 halfDir = normalize(worldLightDir + viewDir);
                float nh = max(0, dot(worldNormal, halfDir));
                float spec = pow(nh, 100 * _Glossiness);
                float4 c = float4(0,0,0,0);
                c.rgb += albedo * (nh * _HighLightIntensity + spec * specular);
                c.rgb += albedo * UnityGlobalAmbientColor.rgb * _AmbientColor.rgb;
                c.a = _Color.a;
                return c;
            }
            ENDCG
        }
    }
 
    FallBack "Diffuse"
}

在修改后的代码中，我们新增了一个_AmbientColor属性，并在frag函数中使用UnityGlobalAmbientColor来获取Unity的全局环境光颜色，并与_AmbientColor属性混合计算。