模板测试是渲染管线中逐片元操作的一环，它的作用是筛选出指定模板的片元，而不符合模板的片元会被舍弃，从而做到一个遮罩的效果。
以下是Unity中实践的一个效果：
场景中可以看出，熊模型和茶壶模型都在差不多的位置，但是正面的框中只能看到熊模型，侧面的框中只能看到茶壶模型，利用的就是模板测试的原理。
以下是shader代码
遮罩的shader代码：
Shader "Test/StencilMask"
{Properties{_ID ("Mask Id", Int) = 0}SubShader{Tags { "RenderType"="Opaque" "Queue"="Geometry+1" }ColorMask 0ZWrite Off//模板遮罩关键代码Stencil{Ref[_ID]Comp AlwaysPass Replace}Pass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);return o;}fixed4 frag (v2f i) : SV_Target{return half4(1, 1, 1, 1);}ENDCG}}
}
游戏物体的shader代码：
Shader "Test/StencilObject"
{Properties{_ColorTint ("Color Tint", Color) = (1,1,1,1)_MainTex ("Base (RGB)", 2D) = "white" {}_BumpMap ("Normalmap", 2D) = "bump" {}_Amount ("Extrusion Amount", Range(-0.5, 0.5)) = 0.1_ID ("Mask Id", Int) = 0}SubShader{Tags { "RenderType"="Opaque" "Queue"="Geometry+2" }LOD 300//被遮罩的游戏物体Stencil{Ref[_ID]Comp Equal}CGPROGRAM#pragma surface surf CustomLambert vertex:myvert finalColor:mycolor addshadow exclude_path:deferred exclude_path:prepass nometa#pragma target 3.0fixed4 _ColorTint;sampler2D _MainTex;sampler2D _BumpMap;half _Amount;struct Input{float2 uv_MainTex;float2 uv_BumpMap;};void myvert (inout appdata_full v){v.vertex.xyz += v.normal * _Amount; }void surf (Input IN, inout SurfaceOutput o){fixed4 tex = tex2D (_MainTex, IN.uv_MainTex);o.Albedo = tex.rgb;o.Alpha = tex.a;o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));}half4 LightingCustomLambert (SurfaceOutput s, half3 lightDir, half atten){half NdotL = dot(s.Normal, lightDir);half4 c;c.rgb = s.Albedo * _LightColor0.rgb * (NdotL * atten);c.a = s.Alpha;return c;}void mycolor(Input IN, SurfaceOutput o, inout fixed color){color *= _ColorTint; }ENDCG}FallBack "Legacy Shaders/Diffuse"
}
之后只要把对应模型的材质球的Mask Id调整成一致就好。
