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I have a scrolling background shader that I am trying to add transparency two, but I can't seem to get it working. Can anyone help me out with this?

Shader "BRS/Environment/Scrolling Background with Alpha" {
    Properties {
        _MainTex ("Base layer (RGB)", 2D) = "white" {}
        //_DetailTex ("2nd layer (RGB)", 2D) = "white" {}
        _ScrollX ("Base layer Scroll speed X", Float) = 1.0
        _ScrollY ("Base layer Scroll speed Y", Float) = 0.0
        //_Scroll2X ("2nd layer Scroll speed X", Float) = 1.0
        //_Scroll2Y ("2nd layer Scroll speed Y", Float) = 0.0
        _Intensity ("Intensity", Float) = 0.5
        _Alpha ("Alpha", Range(0.0, 1.0)) = 1.0
    }

    SubShader {
        Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }

        Lighting Off 
        Fog { Mode Off }
        ZWrite Off

        LOD 100


        CGINCLUDE
        #pragma multi_compile LIGHTMAP_OFF LIGHTMAP_ON
        #include "UnityCG.cginc"
        sampler2D _MainTex;
        //sampler2D _DetailTex;

        float4 _MainTex_ST;
        //float4 _DetailTex_ST;

        float _ScrollX;
        float _ScrollY;
        //float _Scroll2X;
        //float _Scroll2Y;
        float _Intensity;
        float _Alpha;

        struct v2f {
           float4 pos : SV_POSITION;
           float2 uv : TEXCOORD0;
           //float2 uv2 : TEXCOORD1;
           fixed4 color : TEXCOORD1;     
        };


        v2f vert (appdata_full v)
        {
           v2f o;
           o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
           o.uv = TRANSFORM_TEX(v.texcoord.xy,_MainTex) + frac(float2(_ScrollX, _ScrollY) * _Time);
           //o.uv2 = TRANSFORM_TEX(v.texcoord.xy,_DetailTex) + frac(float2(_Scroll2X, _Scroll2Y) * _Time);
           o.color = fixed4(_Intensity, _Intensity, _Intensity, _Alpha);

           return o;
        }
        ENDCG


        Pass {
           CGPROGRAM
           #pragma vertex vert
           #pragma fragment frag
           #pragma fragmentoption ARB_precision_hint_fastest     
           fixed4 frag (v2f i) : COLOR
           {
             fixed4 o;
             fixed4 tex = tex2D (_MainTex, i.uv);
             //fixed4 tex2 = tex2D (_DetailTex, i.uv2);

             //o = (tex * tex2) * i.color;
             o = tex * i.color;

             return o;
           }
           ENDCG 
        }  
    }
    }

Answer 1

0

Add the blend mode after ZWrite Off:

    ...
    ZWrite Off
    Blend SrcAlpha OneMinusSrcAlpha

answered Apr 20 '12 at 04:03 AM

aldonaletto
41.5k ● 16 ● 42 ● 197

I ended up rewriting the shader, but your answer was what I needed thanks!

Apr 25 '12 at 06:39 AM deus_duke

Hey Deus,

Do you think you could post your functional shader code? I'm having a similar problem. Thanks!

Jun 16 '12 at 07:49 PM z4rd0z

@z4rd0z: Your post is not an answer, so don't post it as answer.

I've converted it into a comment.

Jun 16 '12 at 07:50 PM Bunny83

(comments are locked)

Answer 2

Sure. Instead of multiplying to overlay a texture with alpha, you need to use lerp.

// - Unlit

// - Scroll 3 layers /w Multiplicative op

Shader "BRS/Environment/Scroll 3 Layers" { Properties { _MainTex ("Base layer (RGB)", 2D) = "white" {} _FarTex ("2nd layer (RGB)", 2D) = "black" {} _NearTex ("2nd layer (RGB)", 2D) = "black" {} _ScrollX ("Base layer Scroll speed X", Float) = 0.1 _ScrollY ("Base layer Scroll speed Y", Float) = 0.0 _Scroll2X ("2nd layer Scroll speed X", Float) = 0.5 _Scroll2Y ("2nd layer Scroll speed Y", Float) = 0.0 _Scroll3X ("3nd layer Scroll speed X", Float) = 1.0 _Scroll3Y ("3nd layer Scroll speed Y", Float) = 0.0 _ColorIntensity ("Layer Multiplier", Float) = 0.5 }

SubShader{
    Tags {"Queue"="Background" "IgnoreProjector"="True" "RenderType"="Background"}
    LOD 100

    ZWrite Off
    Lighting Off

    CGPROGRAM
    #pragma surface surf NoLighting

    half4 LightingNoLighting (SurfaceOutput s, half3 lightDir, half atten) {
       half4 c;
       c.rgb = s.Albedo;
       return c;
    }

    struct Input {
       float2 uv_MainTex;
       float2 uv_FarTex;
       float2 uv_NearTex;
    };

    sampler2D _MainTex;
    sampler2D _FarTex;
    sampler2D _NearTex;

    half _ScrollX;
    half _ScrollY;
    half _Scroll2X;
    half _Scroll2Y;
    half _Scroll3X;
    half _Scroll3Y;

    fixed _ColorIntensity;

    void surf (Input IN, inout SurfaceOutput o) {
       float2 mainTex_uv = IN.uv_MainTex;
       float2 farTex_uv = IN.uv_FarTex;
       float2 nearTex_uv = IN.uv_NearTex;

       mainTex_uv.x += _ScrollX * _Time.x;
       mainTex_uv.y += _ScrollY * _Time.x;

       farTex_uv.x += _Scroll2X * _Time.x;
       farTex_uv.y += _Scroll2Y * _Time.x;

       nearTex_uv.x += _Scroll3X * _Time.x;
       nearTex_uv.y += _Scroll3Y * _Time.x;

       float4 mainTex = tex2D (_MainTex, mainTex_uv);
       float4 farTex = tex2D (_FarTex, farTex_uv);
       float4 nearTex = tex2D (_NearTex, nearTex_uv);

       float3 previous = lerp(mainTex.rgb, farTex.rgb, farTex.a);
        o.Albedo = lerp(previous.rgb, nearTex.rgb, nearTex.a) * _ColorIntensity;
    }

    ENDCG
}

}

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