Shader "Unlit/Dissolve"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_NoiseTex ("Noise", 2D) = "white" {}
		_Dissolve("Dissolve value", Range(0,2)) = 1
	}
	SubShader
	{
		Tags { "RenderType"="Transparent" }
		ZWrite On
    Blend SrcAlpha OneMinusSrcAlpha
		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;
				UNITY_FOG_COORDS(1)
				 float4 projPos : TEXCOORD2;
				float4 vertex : SV_POSITION;
			};

			sampler2D _MainTex;

			sampler2D _NoiseTex;
			float4 _MainTex_ST;
			float _Dissolve;

			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				UNITY_TRANSFER_FOG(o,o.vertex);
				 o.projPos = ComputeScreenPos (o.vertex);
				return o;
			}

			fixed4 frag (v2f i) : SV_Target
			{
				// sample the texture
				fixed4 col = tex2D(_MainTex, i.uv);
				fixed4 noise = tex2D(_NoiseTex, i.projPos);
				float dissolve = step(noise.r, _Dissolve);
				col = col * dissolve;
				col.a = dissolve;
				// apply fog
				UNITY_APPLY_FOG(i.fogCoord, col);
				return col;
			}
			ENDCG
		}
	}
}