Problem With Cutout Shader - Unwanted Transparency

Unity Engine
1

Note that I am a total newbie in shader programmin, so I’ve been trying to study it.
My intention on this script was to do, at least for now, a Shader that Accepts Tint Color and accepts an Albedo, for each 0 alpha areas on the Albedo, these would cut out from the rendering, this was supposed to be used on a character’s cloathes. There goes the code:

Shader "Custom/PBR Shader"
{
    Properties
    {
        _TintColor ("Colour Tint", color) = (1,1,1,1)
        _MainTex ("Albedo", 2D) = "white" {}
        _CutOff ("CutOff", Range(0,1)) = 0.5
    }

    SubShader
    {
        Tags {"Queue" = "Transparent" "RenderType" = "Opaque"}
        cull off

        CGPROGRAM

        #pragma surface surf Lambert finalcolor:mycolor alpha

        struct Input
        {
            float2 uv_MainTex;
        };

        fixed4 _TintColor;
        void mycolor (Input IN, SurfaceOutput o,inout fixed4 color)
        {
            color *= _TintColor;
        }

        sampler2D _MainTex;
        float _CutOff;
        void surf (Input IN, inout SurfaceOutput o)
        {
            float ca = tex2D(_MainTex, IN.uv_MainTex).a;
            o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;

            if (ca > _CutOff)
                o.Alpha = ca;
            else
                o.Alpha = 0;
        }

        ENDCG

    }
    FallBack "Transparent/Diffuse"
}
Shader "Custom/PBR Shader"
{
    Properties
    {
        _TintColor ("Colour Tint", color) = (1,1,1,1)
        _MainTex ("Albedo", 2D) = "white" {}
        _CutOff ("CutOff", Range(0,1)) = 0.5
    }

    SubShader
    {
        Tags {"Queue" = "Transparent" "RenderType" = "Opaque"}
        cull off

        CGPROGRAM

        #pragma surface surf Lambert finalcolor:mycolor alpha

        struct Input
        {
            float2 uv_MainTex;
        };

        fixed4 _TintColor;
        void mycolor (Input IN, SurfaceOutput o,inout fixed4 color)
        {
            color *= _TintColor;
        }

        sampler2D _MainTex;
        float _CutOff;
        void surf (Input IN, inout SurfaceOutput o)
        {
            float ca = tex2D(_MainTex, IN.uv_MainTex).a;
            o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;

            if (ca > _CutOff)
                o.Alpha = ca;
            else
                o.Alpha = 0;
        }

        ENDCG

    }
    FallBack "Transparent/Diffuse"
}

But the problem is, even fully alpha areas (And I checked the texture plane and those are indeed with no transparency at all) seems a little transparent. And I can’t figure out why. Does anyone know how to help me please? And If you have any optimization or performance advices on the code, please feel free to sugest.

Thanks;
Arthur

2

It sounds like you want an actual cutout shader then, not an alpha blend shader (which is what you’re using).

Instead of alpha in the #pragma surface line you want:
alphatest:_Cutoff

Then in the surf function just output your texture’s alpha value, no need to have the if there.

3

Tried it here… It indeed removed the unwanted transparency, although… the cutOut doesn’t work anymore: the transparency of the texture image is not being recognized anymoro.

4

There’s a terminology issue here. “Cutout” is a hard edge transparency, either on or off. You want alpha blended transparency in addition to hiding areas of full transparency.

You probably want to use a combination of alpha test and alpha blend then, for which you can recreate alpha test in the surf function.

Set the alpha in the #pragma surface line to:
alpha:fade

Then in your surface function use this instead of the if statement you had before:
clip(ca - _CutOff);

If you’re using shadows you’ll also want to add addshadow to the #pragma surface line.

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