c# - 如何使着色器（统一）与特定强度的灯光交互？

Question

我正在为一个 uni 项目开发一个 cel 着色器，我希望它只受超过 x 强度的场景灯光的影响。我正在努力弄清楚如何在代码中实现这一点。我一直在使用的代码是我在网上找到的，并一直在使用它来测试和了解着色器的工作原理。我不确定是否需要实现某种条件语句？我读过的一些信息说，在着色器中使用条件语句会导致性能下降。

我是着色器的新手，任何帮助将不胜感激。

先感谢您 ：）

附言。我仅限于使用 Unity 2018.3.8

        Properties {
    [Header(Base Parameters)]
    _Color ("Tint", Color) = (0, 0, 0, 1)
    _MainTex ("Texture", 2D) = "white" {}
    [HDR] _Emission ("Emission", color) = (0, 0, 0, 1)

    [HDR]
    _SpecularColor("Specular Color", Color) = (0.9, 0.9, 0.9, 1)
    // Controls the size of the specular reflection.
    _Glossiness("Glossiness", Float) = 32
    [HDR]
    _RimColor("Rim Color", Color) = (1,1,1,1)
    _RimAmount("Rim Amount", Range(0, 1)) = 0.716
    // Control how smoothly the rim blends when approaching unlit
    // parts of the surface.
    _RimThreshold("Rim Threshold", Range(0, 1)) = 0.1
}
SubShader {
    Tags{ "RenderType"="Opaque" "Queue"="Geometry"}

    CGPROGRAM

    #pragma surface surf Stepped fullforwardshadows
    #pragma target 3.0

    sampler2D _MainTex;
    fixed4 _Color;
    half3 _Emission;

    float4 _SpecularColor;
    float _Glossiness;      

    float4 _RimColor;
    float _RimAmount;
    float _RimThreshold;    

    float3 worldPos;

    float4 LightingStepped(SurfaceOutput s, float3 lightDir, half3 viewDir, float shadowAttenuation){
        float shadow = shadowAttenuation;

        s.Normal=normalize(s.Normal);

        float diff = dot(s.Normal, lightDir);

        float towardsLightChange = fwidth(diff);
        float lightIntensity = smoothstep(0, towardsLightChange, diff);
        float3 diffuse = _LightColor0.rgb * lightIntensity * s.Albedo;

        float diffussAvg = (diffuse.r + diffuse.g + diffuse.b) / 3;

        float3 halfVector = normalize(viewDir + lightDir);
        float NdotH = dot(s.Normal, halfVector);
        float specularIntensity = pow(NdotH * lightIntensity, _Glossiness * _Glossiness);
        float specularIntensitySmooth = smoothstep(0.005, 0.01, specularIntensity);
        float3 specular = specularIntensitySmooth * _SpecularColor.rgb * diffussAvg;

        float rimDot = 1 - dot(viewDir, s.Normal);

        float rimIntensity = rimDot * pow(dot(lightDir, s.Normal), _RimThreshold);
        rimIntensity = smoothstep(_RimAmount - 0.01, _RimAmount + 0.01, rimIntensity);
        float3 rim = rimIntensity * _RimColor.rgb * diffussAvg;

        float4 color;
        color.rgb = (diffuse + specular + rim)  * shadow;
        color.a = s.Alpha;
        return color;
    }

    struct Input {
        float2 uv_MainTex;
        float3 worldPos;
    };

    void surf (Input i, inout SurfaceOutput o) {
        worldPos = i.worldPos;
        fixed4 col = tex2D(_MainTex, i.uv_MainTex);
        col *= _Color;
        o.Albedo = col.rgb;
        o.Alpha = col.a;

        o.Emission = _Emission;
    }
    ENDCG
}
FallBack "Standard"

}

标签： c#unity3dshaderfragment-shader