Scroll.shader

Shader "Unlit/Scroll"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_SubTex1 ("Subtexture1", 2D) = "white" {}
		_SubTex2 ("Subtexture2", 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 _MainTex, _SubTex1, _SubTex2;
			float4 _MainTex_ST;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				half4 sub;
				half2 uv = i.uv;
				half t = _Time.x - floor(_Time.x);
				uv.y =  i.uv.y + t;
				fixed4 col = tex2D(_MainTex, uv);
        
				uv.y =  i.uv.y + t * 2;
				sub = tex2D(_SubTex1, uv);
    		col.rgb = lerp (col.rgb, sub.rgb, sub.a);
        
				uv.y =  i.uv.y +  t * 4 ;
				sub = tex2D(_SubTex2, uv);
    		col.rgb = lerp (col.rgb, sub.rgb, sub.a);

				return col;
			}
			ENDCG
		}
	}
}