Shader "Custom/UVOffset" {
 Properties {
  _MainTint("Diffuse Tine",Color) = (1,1,1,1)
  _MainTex("Base (RGB)",2D) = "white"{}
  _ScrollXSpeed("X Scroll Speed",Range(0,10)) = 0
  _ScrollYSpeed("Y Scroll Speed",Range(0,10)) = 2
 }
 SubShader {
  Tags { "RenderType"="Opaque" }
  LOD 200

  CGPROGRAM
  // Physically based Standard lighting model, and enable shadows on all light types
  #pragma surface surf Standard fullforwardshadows

  // Use shader model 3.0 target, to get nicer looking lighting
  #pragma target 3.0

  // 定义 Properties 中的属性
  fixed4 _MainTint;
  fixed _ScrollXSpeed;
  fixed _ScrollYSpeed;
  sampler2D _MainTex;

  struct Input {
   float2 uv_MainTex;
  };

  void surf (Input IN, inout SurfaceOutputStandard o) {
   fixed2 scrolledUV = IN.uv_MainTex;
   fixed xScrollValue = _ScrollXSpeed * _Time;
   fixed yScrollValue = _ScrollYSpeed * _Time;
   scrolledUV += fixed2(xScrollValue,yScrollValue);

   // 对贴图进行采样输出
   half4 c = tex2D(_MainTex,scrolledUV);
   o.Albedo = c.rgb * _MainTint;
   o.Alpha = c.a;
  }
  ENDCG
 } 
 FallBack "Diffuse"
}