Unity 通用透明物体漫反射Shader（双面渲染&多光源&光照衰减&法线贴图&凹凸透明度控制）

Shader "MyUnlit/AlphaBlendDiffuse"
{
    Properties
    {
_Color("Color Tint（贴图染色）",Color)=(1,1,1,1)
        _MainTex ("Texture（主贴图）", 2D) = "white" {}
    //bump为unity内置的法线纹理，当未配置任何法线纹理时，bump对应模型自带的法线信息
    _NormalMap("Normal Map（法线贴图）",2D)="bump"{}
_BumpScale("Bump Scale（凹凸程度）",float) = 1.0
_Cutoff("Alpha（整体透明度）",range(0,1)) = 0.5
}
SubShader
{
//透明度混合需要定义的标签
Tags{ "Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent" }//1.Base Pass背面（顺序，透明物体先渲染背面再渲染正面）
Pass
{
//提示此Pass为前向渲染中的Base Pass，计算环境光，自发光，平行光中的阴影，不计算其他叠加光照效果
Tags{ "LightMode" = "ForwardBase" }
//透明度混合需要关闭深度写入
ZWrite Off
//开启混合操作并设置混合类型，此处类型为透明度混合
Blend SrcAlpha OneMinusSrcAlpha
//透明物体要考虑双面渲染，第一个Pass只渲染背面，剔除正面
Cull FrontCGPROGRAM
#pragma vertex vert
#pragma fragment frag
//Base Pass指令，用于得到对应的光照变量
#pragma multi_compile_fwdbase#include "UnityCG.cginc"
//包含接收阴影的宏
#include "AutoLight.cginc"
            #include "Lighting.cginc"fixed4 _Color;
    sampler2D _MainTex;
//用于控制对应纹理的缩放和偏移，格式固定为xx_ST
float4 _MainTex_ST;
sampler2D _NormalMap;
float4 _NormalMap_ST;
float _BumpScale;
fixed _Cutoff;//[0,1]范围内用fixed            struct appdata
            {
                float4 vertex : POSITION;
float3 normal:NORMAL;
float4 tangent:TANGENT;//与法线不同，w需要用于控制朝向
                float2 uv : TEXCOORD0;
            };            struct v2f
            {
//节约空间，xy分量存主贴图uv;zw存法线贴图的
                float4 uv : TEXCOORD0;
                float4 pos : SV_POSITION;//变量名为pos,有关阴影计算的宏中使用了此变量
//寄存器中没法存矩阵，所以分别存矩阵的每一行
float4 TtoW0 : TEXCOORD1;
float4 TtoW1 : TEXCOORD2;
float4 TtoW2 : TEXCOORD3;
SHADOW_COORDS(4)//此阴影纹理坐标存储在TEXCOORD4中
            };//此处采用在世界空间中计算法线
            v2f vert (appdata v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
//用两个分量分别存储贴图的缩放和偏移
                o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
o.uv.zw = TRANSFORM_TEX(v.uv, _NormalMap);float3 worldPos= mul(unity_ObjectToWorld, v.vertex).xyz;
fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
//叉积计算第三个标准正交基轴向，w指示朝向的正负
fixed3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;
//节约空间，顺便将世界空间中的顶点位置存在w分量中
o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
//计算阴影纹理坐标
TRANSFER_SHADOW(o);return o;
            }            fixed4 frag (v2f i) : SV_Target
            {
//还原世界坐标
float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);
//还原出矩阵，用于将纹理从顶点空间（切线空间）变为世界空间，统一计算
float3x3 TtoW= float3x3(i.TtoW0.xyz, i.TtoW1.xyz, i.TtoW2.xyz);
//得到世界空间中的光源方向和视线方向
fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));
//从zw分量中采样出法线并进行凹凸程度的缩放，但此时法线依然处于顶点空间（切线空间）
fixed3 tanNormal = UnpackNormalWithScale(tex2D(_NormalMap, i.uv.zw), _BumpScale);
//通过之前构造的变换矩阵将法线从顶点空间变换到世界空间
fixed3 worldNormal = mul(TtoW, tanNormal);
//采样主纹理并染色，得到反射率
                fixed4 col = tex2D(_MainTex, i.uv);
fixed3 albedo = col.rgb*_Color.rgb;
//计算环境光
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
//计算漫反射
fixed3 diffuse = _LightColor0.rgb*albedo*saturate(dot(lightDir, worldNormal));
//计算光照和阴影衰减值，结果为第一个参数
UNITY_LIGHT_ATTENUATION(atten, i, worldPos);//返回计算结果
                return fixed4(ambient + diffuse * atten, col.a * _Cutoff);
            }
            ENDCG
        }
//2.Base Pass正面
Pass
{
Tags{ "LightMode" = "ForwardBase" }ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha
//透明物体要考虑双面渲染，此Pass只渲染正面，剔除背面
Cull BackCGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile_fwdbase            #include "UnityCG.cginc"
            #include "AutoLight.cginc"
            #include "Lighting.cginc"fixed4 _Color;
    sampler2D _MainTex;
    float4 _MainTex_ST;
    sampler2D _NormalMap;
    float4 _NormalMap_ST;
    float _BumpScale;
    fixed _Cutoff;struct appdata
{
float4 vertex : POSITION;
float3 normal:NORMAL;
float4 tangent:TANGENT;
float2 uv : TEXCOORD0;
};struct v2f
{
float4 uv : TEXCOORD0;
float4 pos : SV_POSITION;float4 TtoW0 : TEXCOORD1;
float4 TtoW1 : TEXCOORD2;
float4 TtoW2 : TEXCOORD3;
SHADOW_COORDS(4)
};v2f vert(appdata v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
o.uv.zw = TRANSFORM_TEX(v.uv, _NormalMap);float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);fixed3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);TRANSFER_SHADOW(o);return o;
}fixed4 frag(v2f i) : SV_Target
{float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);float3x3 TtoW = float3x3(i.TtoW0.xyz, i.TtoW1.xyz, i.TtoW2.xyz);fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));fixed3 tanNormal = UnpackNormalWithScale(tex2D(_NormalMap, i.uv.zw), _BumpScale);fixed3 worldNormal = mul(TtoW, tanNormal);fixed4 col = tex2D(_MainTex, i.uv);
fixed3 albedo = col.rgb*_Color.rgb;fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;fixed3 diffuse = _LightColor0.rgb*albedo*saturate(dot(lightDir, worldNormal));UNITY_LIGHT_ATTENUATION(atten, i, worldPos);return fixed4(ambient + diffuse * atten, col.a * _Cutoff);
}
ENDCG
}
//3.Add Pass正常渲染
Pass
{
//提示此Pass为前向渲染中的Add Pass，计算其他叠加光照效果，每个光源计算一次
Tags{ "LightMode" = "ForwardAdd" }ZWrite Off
Blend SrcAlpha One
Cull BackCGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
//Add Pass指令，用于得到对应的光照变量
            //#pragma multi_compile_fwdadd
//阴影情况下使用:
#pragma multi_compile_fwdadd_fullshadows            #include "UnityCG.cginc"
            #include "AutoLight.cginc"
            #include "Lighting.cginc"fixed4 _Color;
    sampler2D _MainTex;
    float4 _MainTex_ST;
    sampler2D _NormalMap;
    float4 _NormalMap_ST;
    float _BumpScale;
    fixed _Cutoff;struct appdata
{
float4 vertex : POSITION;
float3 normal:NORMAL;
float4 tangent:TANGENT;
float2 uv : TEXCOORD0;
};struct v2f
{
float4 uv : TEXCOORD0;
float4 pos : SV_POSITION;float4 TtoW0 : TEXCOORD1;
float4 TtoW1 : TEXCOORD2;
float4 TtoW2 : TEXCOORD3;
SHADOW_COORDS(4)
};v2f vert(appdata v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
o.uv.zw = TRANSFORM_TEX(v.uv, _NormalMap);float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);fixed3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);TRANSFER_SHADOW(o);return o;
}fixed4 frag(v2f i) : SV_Target
{float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);float3x3 TtoW = float3x3(i.TtoW0.xyz, i.TtoW1.xyz, i.TtoW2.xyz);fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));fixed3 tanNormal = UnpackNormalWithScale(tex2D(_NormalMap, i.uv.zw), _BumpScale);fixed3 worldNormal = mul(TtoW, tanNormal);fixed4 col = tex2D(_MainTex, i.uv);
fixed3 albedo = col.rgb*_Color.rgb;fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;fixed3 diffuse = _LightColor0.rgb*albedo*saturate(dot(lightDir, worldNormal));UNITY_LIGHT_ATTENUATION(atten, i, worldPos);return fixed4(ambient + diffuse * atten, col.a * _Cutoff);
}
ENDCG
}
    }
//无阴影
//FallBack "Transparent/VertexLit"
//强制产生阴影
FallBack "VertexLit"
}