一、Shader基础：6、Shader做的UV动画，波光粼粼效果

参照别人的代码，实现一条波光粼粼的小鱼

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/UVShader"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _SubTex ("Texture", 2D) = "white" {}
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        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 _SubTex;
            sampler2D _MainTex;

            float4 _MainTex_ST;
            
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);//对UV进行Tiling与Offset变换
                
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                float2 uv_offset = float2(0, 0);
                uv_offset.x = _Time.y * 0.25;
                uv_offset.y = _Time.y * 0.25;
                // sample the texture
                fixed4 linght_color = tex2D(_SubTex, i.uv + uv_offset);//光照混合
                fixed4 col = tex2D(_MainTex, i.uv) + linght_color;//颜色混合
                return col;
            }
            ENDCG
        }
    }
}