Unity Shader模板测试-描边

• 先把模型的 顶点 往 法线方向 偏移一个值（这个就是描边的宽度值，可以理解为将模型放大了），可以在观察空间 或者 世界空间、模型空间 偏移，只要和 法线 在同一空间下。
• 对比 模板缓冲区 的参考值 Ref=1，因为第一个 pass 写入的参考值是 1，所以这个pass中就要不等1才让它通过，这样就能得到一个 差值区域，即描边的区域。
• 深度测试，让被遮挡部分才让它通过，即 ZTest Greater，done！

Shader "Custom/Unlit-Texture-Outline" ｛
    Properties｛
        _MainTex("Base (RGB)", 2D) = "white" ｛｝
        _OutlineColor("Outline Color", Color) = (1,1,0,1) //描边颜色
        _Outline("Outline width", Range(0.0, 0.5)) = 0.03 // 描边宽度
    ｝
    CGINCLUDE
    #include "UnityCG.cginc"
    struct appdata_t ｛
        float4 vertex : POSITION;
        float2 texcoord : TEXCOORD0;
        float3 normal : NORMAL;
    ｝;
    struct v2f ｛
        float4 vertex : SV_POSITION;
        half2 texcoord : TEXCOORD0;
    ｝;
    sampler2D _MainTex;
    float4 _MainTex_ST;
    float _Outline;
    float4 _OutlineColor;
    v2f vert(appdata_t v)
    ｛
        v2f o;
        o.vertex = UnityObjectToClipPos(v.vertex);
        o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
        return o;
    ｝
    v2f vert_outline(appdata_t v)
    ｛
        v2f o;
        // 方式一，观察空间 下往法线偏移顶点
        float4 viewPos = mul(UNITY_MATRIX_MV, v.vertex);
        //float3 viewNorm = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal);
        float3 viewNorm = mul(v.normal, (float3x3)UNITY_MATRIX_T_MV);
        float3 offset = normalize(viewNorm) * _Outline;
        viewPos.xyz += offset;
        o.vertex = mul(UNITY_MATRIX_P, viewPos);
        //方式二，世界空间 下往法线偏移顶点
        //float4 worldPos = mul(unity_ObjectToWorld, v.vertex);
        //float3 worldNormal = UnityObjectToWorldNormal(v.normal);
        //float3 offset = normalize(worldNormal) * _Outline;
        //worldPos.xyz += offset;
        //o.vertex = mul(UNITY_MATRIX_VP, worldPos);
        return o;
    ｝
    ENDCG
    SubShader｛
        Tags｛ "Queue" = "Transparent" "RenderType" = "Opaque" ｝
        Pass｛ // 正常绘制
            Stencil
            ｛
                Ref 1
                Comp Always
                Pass Replace
                ZFail Replace
            ｝
            ZTest LEqual
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            fixed4 frag(v2f i) : SV_Target
            ｛
                fixed4 col = tex2D(_MainTex, i.texcoord);
                return col;
            ｝
            ENDCG
        ｝
        Pass｛ // 遮挡部分绘制描边
            ZTest Greater
            ZWrite Off
            //Blend DstAlpha OneMinusDstAlpha
            Stencil｛
                Ref 1
                Comp NotEqual
            ｝
            CGPROGRAM
            #pragma vertex vert_outline
            #pragma fragment frag
            half4 frag(v2f i) :COLOR
            ｛
                return _OutlineColor;
            ｝
            ENDCG
        ｝
    ｝
｝

// 这种方式的描边不适合做遮挡部分描边，且不遮挡部分的效果也没有 模板测试 那种方式好
Shader "ITS/test/testOutline_cull" ｛
Properties｛
    _MainTex("Base (RGB)", 2D) = "white" ｛｝
    _OutlineColor("Outline Color", Color) = (1,1,0,1)
    _Outline("Outline width", Range(0.0, 0.5)) = 0.03
｝
CGINCLUDE
#include "UnityCG.cginc"
struct appdata_t ｛
    float4 vertex : POSITION;
    float2 texcoord : TEXCOORD0;
    float3 normal : NORMAL;
｝;
struct v2f ｛
    float4 vertex : SV_POSITION;
    half2 texcoord : TEXCOORD0;
｝;
sampler2D _MainTex;
float4 _MainTex_ST;
float _Outline;
float4 _OutlineColor;
v2f vert(appdata_t v)
｛
    v2f o;
    o.vertex = UnityObjectToClipPos(v.vertex);
    o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
    return o;
｝
v2f vert_outline(appdata_t v)
｛
    v2f o;
    // 方式一，观察空间 下往法线偏移顶点
    float4 viewPos = mul(UNITY_MATRIX_MV, v.vertex);
    //float3 viewNorm = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal);
    float3 viewNorm = mul(v.normal, (float3x3)UNITY_MATRIX_T_MV);
    float3 offset = normalize(viewNorm) * _Outline;
    viewPos.xyz += offset;
    o.vertex = mul(UNITY_MATRIX_P, viewPos);
    //方式二，世界空间 下往法线偏移顶点
    //float4 worldPos = mul(unity_ObjectToWorld, v.vertex);
    //float3 worldNormal = UnityObjectToWorldNormal(v.normal);
    //float3 offset = normalize(worldNormal) * _Outline;
    //worldPos.xyz += offset;
    //o.vertex = mul(UNITY_MATRIX_VP, worldPos);
    return o;
｝
ENDCG
SubShader｛
    Tags｛ "Queue" = "Transparent" "RenderType" = "Opaque" ｝
    Pass｛
        ZTest LEqual
        Cull Back
        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        fixed4 frag(v2f i) : SV_Target
        ｛
            fixed4 col = tex2D(_MainTex, i.texcoord);
            return col;
        ｝
        ENDCG
    ｝
    Pass｛
        // ZTest Greater
        ZWrite Off
        Cull Front
        Offset 100,0
        CGPROGRAM
        #pragma vertex vert_outline
        #pragma fragment frag
        half4 frag(v2f i) : COLOR
        ｛
            return _OutlineColor;
        ｝
        ENDCG
    ｝
｝
｝