文字をランダムに表示するシェーダー　GPUInstancingでオブジェクト毎に表示を変える（カメラの距離で描画が変わってしまうのでだめ）

charshader.shader

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

Shader "Unlit/charshader_babel"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}

		_sw("string length in line",int) = 30
		_line("line",int) = 20
		_source("sourceChars in line",int)=1
		_seed("seed",float) = 0
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#pragma multi_compile_instancing
			#include "UnityCG.cginc"

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

				uint instanceID : SV_InstanceID;
			};

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

			sampler2D _MainTex;
			float4 _MainTex_ST;
			int _sw;
			int _line;
			int _source;
			int _seed;

			v2f vert (appdata v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				#if defined(UNITY_INSTANCING_ENABLED)
				
				o.instanceID = v.instanceID;
				#endif 
			
				return o;
			}
			float random (float2 p,float seed) 
			{ 
				return frac(sin(dot(p, fixed2(12.9898,78.233+ seed))) * 43758.5453);
			}

			float noise(float2 st,float seed)
			{
				float2 p = floor(st);
				return random(p,seed);
			}

			fixed4 frag (v2f i) : SV_Target
			{

				int sw = _sw;	//列の文字数
				int sh = _line;	//行の文字数
				int w = _source;
				//float3 worldpos = mul(unity_ObjectToWorld, float4(0,0,0,1)).xyz;
				//float seed = worldpos.x + worldpos.y + worldpos.z;
				uint seed = _seed;


				#if defined(UNITY_INSTANCING_ENABLED)
				seed += i.instanceID;

				#endif
				float c = noise( i.uv*float2(sw,sh) + 1,seed);
				//return fixed4(c,c,c,1);

				float x = frac(floor(c*w*w)/w);
				float y = floor(c*w)/w;
				float dx = frac(i.uv.x*sw)/w;
				float dy = frac(i.uv.y*sh)/w;
				fixed4 col = tex2D(_MainTex,float2(x+dx,y+dy));
				return col;

			}

			ENDCG
		}
	}
}