Unity Shader学习笔记/外发光效果

实现物体外发光的Shader要分成两个Pass进行，第一个Pass渲染物体正面，剔除背面；第二个Pass渲染背面（剔除正面），通过扩展法线方向顶点，再进行颜色计算。

Shader代码：

Shader "OutAndRimLight"
{
    Properties
    {
        _SpecularGlass("SpecularGlass", Range(0, 64)) = 32
        _ObjColor("ObjColor", color) = (1, 1, 1, 1)
        _RimColor("RimColor", color) = (1, 1, 1, 1)
        _RimStrength("RimStrength", Range(0.0001, 3.0)) = 0.1
        _AtmoColor("Atmosphere Color", Color) = (0, 0.4, 1.0, 1)
        _Size("Size", Float) = 0.1
        _OutLightPow("LightPow", Float) = 5
        _OutLightStrength("Strength", Float) = 15
    }

    SubShader
    {
        Pass  //pass1 实现rim和贴图颜色
        {
            Tags{ "RenderType" = "Opaque" }
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            #include "Lighting.cginc"

            float _SpecularGlass;
            fixed4 _ObjColor;
            fixed4 _RimColor;
            float _RimStrength;

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL;

            };

            struct v2f
            {
                float3 worldNormal:NORMAL;
                float4 vertex : SV_POSITION;
                float3 worldPos : TEXCOORD1;

            };

            v2f vert(appdata_base v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject);
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
                return o;

            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
                fixed3 diffuse = max(0.0, dot(worldNormal, worldLightDir));
                fixed3 diffuseColor = diffuse  * _LightColor0.xyz;
                //计算reflect方向
                fixed3 reflectDir = normalize(reflect(-worldLightDir, worldNormal));
                //计算视角方向
                fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos);
                //specular分量
                fixed3 specular = pow(max(0.0, dot(reflectDir, viewDir)), _SpecularGlass);
                fixed3 specularColor = specular * _LightColor0.xyz;
                //环境光
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * _ObjColor;
                //RimLight
                fixed3 worldViewDir = normalize(viewDir);
                float rim = 1 - max(0, dot(worldViewDir, worldNormal));
                fixed3 rimColor = _RimColor * pow(rim, 1 / _RimStrength);
                return fixed4(diffuseColor + specularColor + ambient + rimColor, 0);
            }

            ENDCG
        }

        Pass  //pass2 实现OutLight
        {
            Name "AtmosphereBase"
            Tags{ "LightMode" = "Always" }
            Cull Front
            Blend SrcAlpha One
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            uniform float _Size;
            uniform float4 _AtmoColor;
            uniform float _OutLightPow;
            uniform float _OutLightStrength;

            struct v2f
            {
                float3 normal : TEXCOORD0;
                float3 worldPos : TEXCOORD1;
                float4 vertex : SV_POSITION;
            };

            v2f vert(appdata_base v)
            {
                v2f o;
                v.vertex.xyz += v.normal * _Size;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.normal = v.normal;
                o.worldPos = mul(unity_ObjectToWorld, v.vertex);
                return o;
            }

            fixed4 frag(v2f i) : COLOR
            {
                i.normal = normalize(i.normal);
                //渲染的是背面，视角方向相反
                float3 viewDir = normalize(i.worldPos - _WorldSpaceCameraPos.xyz); 
                float4 color = _AtmoColor;
                //视角法线与模型法线点积形成中间指为1向四周逐渐衰减为0的点积值，赋给透明通道，形成光晕效果
                color.a = pow(saturate(dot(viewDir, i.normal)), _OutLightPow);
                color.a *= _OutLightStrength * dot(viewDir, i.normal);
                return color;
            }

            ENDCG
        }
    }
}

 参考：(17条消息) UnityShader应用——外发光实现_noEnoughChief的博客-CSDN博客_unity 外发光shader