Shader "XGame/TestTime"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _ScrollY ("Scroll Speed", Range(0, 1)) = 1
        _MoveTime("Move Time", float) = 0
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            // #pragma multi_compile_fog
            
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _ScrollY;
            float _MoveTime;

            float2 ModuloUV(float2 uv)
            { // 取模运算,返回小数部分
                // uv.y -= floor(uv.y);
                return uv - floor(uv);
                // return frac(uv);
            }
            v2f vert (appdata v)
            {
                v2f o;
                // v.vertex.y = sin(v.vertex.x+_Time.y);
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv + float2(0, _ScrollY * _MoveTime);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, ModuloUV(i.uv));     
                return col;
            }
            ENDCG
        }
    }
}