line artifacts between uv on using fmod

I have a little problem with a shader I wrote.
There are line artifacts between the uv tiling of the texture.
Is there something I'm doing wrong or does uv's are not between 0.0 and 1.0?
I have no idea what could be causing this.

Here is a screenshot of the problem:


and this is the Texture:


Here is the code:

Code (csharp):

1.  
2. Shader "custom/Test Shader"
3. {
4.     Properties
5.     {
6.         _MainTex ("Base (RGB)", 2D) = "white" {}
7.     }
8.     SubShader
9.     {
10.         Tags { "RenderType"="Opaque" }
11.        
12.         CGPROGRAM
13.         #pragma surface surf Lambert
14.  
15.         sampler2D _MainTex;
16.  
17.         struct Input
18.         {
19.             float2 uv_MainTex;
20.         };
21.        
22.         void surf (Input IN, inout SurfaceOutput o)
23.         {
24.             float2 pgUvMainTex1 = float2(fmod(IN.uv_MainTex.x,0.5), fmod(IN.uv_MainTex.y,0.5)+0.5);
25.             half4 color1 = tex2D (_MainTex, pgUvMainTex1);
26.  
27.             o.Albedo = color1.rgb;
28.             o.Alpha = 1;
29.         }
30.         ENDCG
31.     }
32.     FallBack "Diffuse"
33. }
34.  
35.  

 

http://stackoverflow.com/questions/...borders-when-tiling-texture/15792064#15792064

 

Thanks for the reply. Now I know what the problem is. (mipmap)

Hmm, is there another way to get atlas texture working on my shader?
I need it for my terrain for detail textures etc.

Or is it possible to extend the editor (inspector) for terrain painting with more textures on one splat (like diffuse, normal, detail, ...)?