Shader CG not taking tiling into account

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Hey guys! im pretty new at creating shaders. Im currently working on a shader that blendos two textures and takes into account the alpha i cutoff from the main texture. It works fine, until i try to use offset and scale to set the correct drawing within the spritesheet / atlas. For some reason i do not understand the main texture is not taking the offset and scale values i assign at the inspector, whereas the blend texture is. Could you guys guide me a bit through?

this is my script so far:

 Shader "My Shaders/Unlit/Mixer Alpha Blend" {
     
 Properties {
     _Blend ("Blend", Range (0,1)) = 0.0 
     _MainTex ("Texture (A = Transparency)", 2D) = ""
     _BlendTexture ("BlendTexture (A = Transparency)", 2D) = ""
     _Cutoff ("Alpha Cutoff", Float) = 0.5
     
 } 
 
 SubShader {
     Tags {"Queue"="transparent" "RenderType"="transparent" }
     ZWrite Off
     Blend SrcAlpha OneMinusSrcAlpha
      Lighting Off
     
      
      Pass { 
     CGPROGRAM
     #pragma vertex vert
     #pragma fragment frag
 
     #include "UnityCG.cginc"
        
         sampler2D _MainTex;
            sampler2D _BlendTexture;
            uniform float _Cutoff;
            uniform float _Blend;
            
            
            
            float4 _MainTex_ST;
            float4 _BlendTexture_ST;
            
            struct v2f {
     float4  pos : SV_POSITION;
     float2  uv : TEXCOORD0;
     float2  uv2 : TEXCOORD1;
 };
 
            
        v2f vert (appdata_base v){
     v2f o;
     o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
     o.uv = TRANSFORM_TEX (v.texcoord, _MainTex);
     o.uv2 = TRANSFORM_TEX (v.texcoord, _BlendTexture);
     return o;
 }
 
            
            
            half4 frag (v2f i) : COLOR{
            
            float4 MyColor = tex2D (_BlendTexture, i.uv2).rgba;
            float4 MyAlpha = tex2D (_MainTex, i.uv).rgba;
            
            if (MyAlpha.a < _Cutoff)
                // alpha value less than user-specified threshold?
             {
                discard; // yes: discard this fragment
             }
       return lerp(MyAlpha, MyColor , _Blend);
      
     
             }
             
        
         ENDCG
         }
       
 }
 
 }

Edited: modified script, it now works as expected!

Answer 1

Best Answer

Answer by tanoshimi · Jan 13, 2014 at 03:50 PM

You use TRANSFORM_TEX in the vertex method, but first you need to declare a new variable:

 float4 _MainTexure_ST;

_ST variables are automatically populated with the texture scale (x,y) and offset (z,w) values from the correspondingly-named texture (in this case, _MainTexure).

Then, create a vertex method and, in it, write to the uv property of the output structure using the TRANSFORM_TEX macro:

 o.uv = TRANSFORM_TEX(v.texcoord, _MainTexure);

(assuming o is your output structure, and v is your input structure)

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Complex77 · Jan 13, 2014 at 04:06 PM 0

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Hi, thanks for your help, this is what i got so far: Shader "$$anonymous$$y Shaders/Unlit/$$anonymous$$ixer Alpha Blend" {

 Properties {
     _Blend ("Blend", Range (0,1)) = 0.0 
     _$$anonymous$$ainTex ("Texture (A = Transparency)", 2D) = ""
     _BlendTexture ("BlendTexture (A = Transparency)", 2D) = ""
     _Cutoff ("Alpha Cutoff", Float) = 0.5
     
 } 
 
 SubShader {
     Tags {"Queue"="transparent" "RenderType"="transparent" }
     ZWrite Off
     Blend SrcAlpha One$$anonymous$$inusSrcAlpha
      Lighting Off
     
      
      Pass { 
     CGPROGRA$$anonymous$$
     #pragma vertex vert_img
     #pragma fragment frag
 
     #include "UnityCG.cginc"
        
         sampler2D _$$anonymous$$ainTex;
            sampler2D _BlendTexture;
            uniform float _Cutoff;
            uniform float _Blend;
            
            
            
            float4 _$$anonymous$$ainTex_ST;
            
            
            struct v2f {
     float4  pos : SV_POSITION;
     float2  uv : TEXCOORD0;
 };
 
            
        v2f vert (appdata_base v){
     v2f o;
     o.pos = mul (UNITY_$$anonymous$$ATRIX_$$anonymous$$VP, v.vertex);
     o.uv = TRANSFOR$$anonymous$$_TEX (v.texcoord, _$$anonymous$$ainTex);
     return o;
 }
 
            
            
            half4 frag (v2f i) : COLOR{
            
            float4 $$anonymous$$yColor = tex2D (_BlendTexture, i.uv).rgba;
            float4 $$anonymous$$yAlpha = tex2D (_$$anonymous$$ainTex, i.uv).rgba;
            
            if ($$anonymous$$yAlpha.a < _Cutoff)
                // alpha value less than user-specified threshold?
             {
                discard; // yes: discard this fragment
             }
       return lerp($$anonymous$$yAlpha, $$anonymous$$yColor , _Blend);
      
     
             }
             
        
         ENDCG
         }
       
 }
 
 }

but it does not seem to take any effect, any ideas why? thanks again!

Complex77 · Jan 13, 2014 at 04:34 PM 1

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i did it! thanks! the error was at line 20 where i called a wrong vertex: #pragma vertex vert

tanoshimi · Jan 13, 2014 at 04:44 PM 0

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Great, well done!

Answer 2

Answer by Hoeloe · Jan 13, 2014 at 09:56 AM

I think it's because you're using the same UV coordinate for both textures. You're necessarily taking the same point from both, which is i.uv. You'll need to do some transformation to make it work. If I remember correctly, you can do this with the TRANSFORM_TEX function.

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Complex77 · Jan 13, 2014 at 03:26 PM 0

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i took a quick look at this but i was not able to solve the issue, could you guide me a little bit further? should i call transform_tex in my frag method? before i call i.uv?

Shader CG not taking tiling into account

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