Unity Shader unity文档学习笔记(十二)：shader实现 无限滚动背景

需要滚动的背景图片！！！！ 需要设置图片的WrapMode为Repeat

shader 比较简单 就是UV坐标做一个偏移 偏移的值保持在1以内就好了

Shader "Unlit/UIScrollingBackground"
{
    Properties
    {
        _MainTex ("BaseTexture(RGB)", 2D) = "white" {}
        _ScrollXBaseSpeed ("BaseSpeed", Float) = 1.0
    }
    SubShader
    {
        //如果是UI就需要下面这些东西
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        //到此结束   如果不是UI可以删掉这段
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

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

            sampler2D _MainTex;
            float4 _MainTex_ST;
        
            float _ScrollXBaseSpeed;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex) + frac(float2(_ScrollXBaseSpeed, 0) * _Time.y);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {

                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv);
             
                return col;
            }
            ENDCG
        }
    }
}