金属流，高光流，粗照度流 傻傻分不清

half4 SpecularGloss(float2 uv)
{
    half4 sg;
#ifdef _SPECGLOSSMAP
    #if defined(_SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A)
        sg.rgb = tex2D(_SpecGlossMap, uv).rgb;
        sg.a = tex2D(_MainTex, uv).a;
    #else
        sg = tex2D(_SpecGlossMap, uv);
    #endif
    sg.a *= _GlossMapScale;
#else
    sg.rgb = _SpecColor.rgb;
    #ifdef _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
        sg.a = tex2D(_MainTex, uv).a * _GlossMapScale;
    #else
        sg.a = _Glossiness;
    #endif
#endif
    return sg;
}

half2 MetallicGloss(float2 uv)
{
    half2 mg;

#ifdef _METALLICGLOSSMAP
    #ifdef _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
        mg.r = tex2D(_MetallicGlossMap, uv).r;
        mg.g = tex2D(_MainTex, uv).a;
    #else
        mg = tex2D(_MetallicGlossMap, uv).ra;
    #endif
    mg.g *= _GlossMapScale;
#else
    mg.r = _Metallic;
    #ifdef _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
        mg.g = tex2D(_MainTex, uv).a * _GlossMapScale;
    #else
        mg.g = _Glossiness;
    #endif
#endif
    return mg;
}

half2 MetallicRough(float2 uv)
{
    half2 mg;
#ifdef _METALLICGLOSSMAP
    mg.r = tex2D(_MetallicGlossMap, uv).r;
#else
    mg.r = _Metallic;
#endif

#ifdef _SPECGLOSSMAP
    mg.g = 1.0f - tex2D(_SpecGlossMap, uv).r;
#else
    mg.g = 1.0f - _Glossiness;
#endif
    return mg;
}

　　

inline FragmentCommonData SpecularSetup (float4 i_tex)
{
    half4 specGloss = SpecularGloss(i_tex.xy);
    half3 specColor = specGloss.rgb;
    half smoothness = specGloss.a;

    half oneMinusReflectivity;
    half3 diffColor = EnergyConservationBetweenDiffuseAndSpecular (Albedo(i_tex), specColor, /*out*/ oneMinusReflectivity);

    FragmentCommonData o = (FragmentCommonData)0;
    o.diffColor = diffColor;
    o.specColor = specColor;
    o.oneMinusReflectivity = oneMinusReflectivity;
    o.smoothness = smoothness;
    return o;
}

inline FragmentCommonData RoughnessSetup(float4 i_tex)
{
    half2 metallicGloss = MetallicRough(i_tex.xy);
    half metallic = metallicGloss.x;
    half smoothness = metallicGloss.y; // this is 1 minus the square root of real roughness m.

    half oneMinusReflectivity;
    half3 specColor;
    half3 diffColor = DiffuseAndSpecularFromMetallic(Albedo(i_tex), metallic, /*out*/ specColor, /*out*/ oneMinusReflectivity);

    FragmentCommonData o = (FragmentCommonData)0;
    o.diffColor = diffColor;
    o.specColor = specColor;
    o.oneMinusReflectivity = oneMinusReflectivity;
    o.smoothness = smoothness;
    return o;
}

inline FragmentCommonData MetallicSetup (float4 i_tex)
{
    half2 metallicGloss = MetallicGloss(i_tex.xy);
    half metallic = metallicGloss.x;
    half smoothness = metallicGloss.y; // this is 1 minus the square root of real roughness m.

    half oneMinusReflectivity;
    half3 specColor;
    half3 diffColor = DiffuseAndSpecularFromMetallic (Albedo(i_tex), metallic, /*out*/ specColor, /*out*/ oneMinusReflectivity);

    FragmentCommonData o = (FragmentCommonData)0;
    o.diffColor = diffColor;
    o.specColor = specColor;
    o.oneMinusReflectivity = oneMinusReflectivity;
    o.smoothness = smoothness;
    return o;
}