练手之RimLight

简单写写，练下手~

Shader "James/VP Shader/RimLight"
{
    Properties
    {
        _MainTex("MainTex", 2D) = "white" {}
        _Color("Color", Color) = (, , , )
        _RimColor("RimColor", Color) = (, , , )
        _RimPower("RimPower", Range(, )) = 0.1
        _RimIntensity("RimIntensity", Range(, )) =
    }

    SubShader
    {
        Tags { "Queue" = "Transparent" }
        Pass
        {
            ZWrite Off
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct v2f
            {
                float4 pos : SV_POSITION;
                float3 color : COLOR0;
                float2 uv : TEXCOORD0;
                float3 normal : TEXCOORD1;
                float3 objViewDir : TEXCOORD2;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _Color;

            v2f vert(appdata_base v)
            {
                v2f o;
                o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                o.normal = v.normal;
                o.objViewDir =  normalize(ObjSpaceViewDir(v.vertex));
                o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                return o;
            }

            float4 _RimColor;
            float _RimPower;
            float _RimIntensity;

            half4 frag(v2f i) : COLOR
            {
                float rimSin =  - max(, dot(i.normal, i.objViewDir));
                float rimFactor = pow(rimSin, _RimPower) * _RimIntensity;
                float3 rimColor = rimFactor * _RimColor;

                float4 mainColor = tex2D(_MainTex, i.uv);
                float4 finalColor = mainColor * _Color;
                finalColor.rgb +=rimColor;
                return finalColor;
            }

            ENDCG
        }
    }
    FallBack "VertexLit"
}

　　　将上面的Shader改写一下，添加BumpTex，并使用一张RimTex来映射边缘光的强度：

Shader "James/VP Shader/BumpRimLight"
{
    Properties
    {
        _MainTex("MainTex", 2D) = "white" {}
        _BumpTex("BumpTex", 2D) = "bump" {}
        _Color("Color", Color) = (, , , )
        _RimColor("RimColor", Color) = (, , , )
        _RimIntensity("RimIntensity", Range(, )) = 0.1
        _RimTex("RimTex", 2D) = "white" {}
    }

    SubShader
    {
        Tags { "Queue" = "Transparent" }
        Pass
        {
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct v2f
            {
                float4 pos : SV_POSITION;
                float3 color : COLOR0;
                float2 uv : TEXCOORD0;
                float3 tangentSpackLightDir : TEXCOORD1;
            };

            sampler2D _MainTex;
            sampler2D _BumpTex;
            sampler2D _RimTex;
            float4 _MainTex_ST;
            float4 _BumpTex_ST;
            float4 _RimTex_ST;
            float4 _Color;
            float4 _RimColor;
            float _RimIntensity;

            v2f vert(appdata_tan v)
            {
                v2f o;
                o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                float3 objViewDir =  normalize(ObjSpaceViewDir(v.vertex));
                o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

                // 副法向量
                float3 binormal = cross(normalize(v.vertex), normalize(v.tangent.xyz));
                // 切空间矩阵
                float3x3 rotation = float3x3(v.tangent.xyz, binormal, v.normal);
                // 切空间视线方向
                o.tangentSpackLightDir = mul(rotation, objViewDir);

                return o;
            }

            half4 frag(v2f i) : COLOR
            {
                // 切空间法线，NormalMap默认带的是切空间的值
                half3 tangentSpaceNormal = (tex2D(_BumpTex, i.uv).rgb * 2.0) - 1.0;
                float rimFactor =  - max(, dot(tangentSpaceNormal, i.tangentSpackLightDir));
                float rimIntensity = tex2D(_RimTex, rimFactor.xx).r;
                float3 rimColor = rimIntensity * _RimColor  * _RimIntensity;

                float4 mainColor = tex2D(_MainTex, i.uv);
                float4 finalColor = mainColor * _Color;
                finalColor.rgb += rimColor;
                return finalColor;
            }

            ENDCG
        }
    }
    FallBack "VertexLit"
}

　　　注意上述代码是在切空间中计算rim的颜色强度。