Unity 5 Custom Terrian Shader appears blurry.

I created this shader on based on Unity’s Legacy Shader, everything works as intended but the textures appear blurry as soon as I replace the terrain with this shader. I tried changing the import settings of the textures and I also tried changing base distance property. From what I have noticed the base distance property of terrain settings had no effect when I was using this custom shader. I tried to use a script to change it during runtime but there’s still no effect.

Shader "Normal /LegacyDiffuseRadius" {

	Properties{
		_Color("Main Color", Color) = (1,1,1,1)
		_MainTex("Base (RGB)", 2D) = "white" {}

	//Radius
	_Center("Center", Vector) = (0,0,0,0)
		_Radius("Radius", Float) = 0.5
		_RadiusColor("Radius Color", Color) = (1,0,0,1)
		_RadiusWidth("Radius Width", Float) = 2

	}
		SubShader{
		Tags{ "RenderType" = "Opaque" }
		LOD 200

		CGPROGRAM
#pragma surface surf Lambert
#pragma surface surf Standard fullforwardshadows
#pragma target 3.0

		sampler2D _MainTex;
	fixed4 _Color;
	//Radius
	float3 _Center;
	float _Radius;
	fixed4 _RadiusColor;
	float _RadiusWidth;


	struct Input {
		float2 uv_MainTex;
		float3 worldPos;
	};

	void surf(Input IN, inout SurfaceOutput o) {
		fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
		float d = distance(_Center, IN.worldPos);
		if (d > _Radius && d < _Radius + _RadiusWidth)
			o.Albedo = _RadiusColor;
		else
			o.Albedo = tex2D(_MainTex, IN.uv_MainTex).rgb;
		o.Albedo = c.rgb;
		o.Alpha = c.a;
	}
	ENDCG
	}

		Fallback "Legacy Shaders/VertexLit"
}

You can’t implicitly use a normal shader with the terrain. It works, but texturing is handled differently for terrains. In Unity, and in general, terrains use ‘splat maps’; basically a collection of textures and masks allowing for multiple textures to be applied at once, as well as generating mip maps for the whole terrain. If you don’t account for these factors, it will automatically use the highest mip map available, which is why your terrain is blurry. If you want to see an actual terrain shader, you can download the built in shaders and modify Unity’s own.

https://unity3d.com/get-unity/download/archive