Shader "Metropolia/OldFilm"
{
	Properties
	{
		_MainTex("Main Tex", 2D) = "white" {}
		_FilmTex("Film Tex", 2D) = "white" {}
		_FrameCount("Frame Count", int) = 4
		_FrameSpeed("Frame Speed", float) = 10
		_Amount("Amount", range(0,1)) = 1
	}

	SubShader
	{
		Pass
		{
			CGPROGRAM

			#pragma vertex vert_img
			#pragma fragment frag
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			sampler2D _FilmTex;
			int _FrameCount;
			float _FrameSpeed;
			float _Amount;

			fixed4 frag(v2f_img i) : SV_Target
			{
				fixed4 c = tex2D(_MainTex, i.uv);
				fixed4 bw = Luminance(c);
				c = lerp(c, bw, _Amount);
				float s = 1.0 / _FrameCount;
				float m = tex2D(_FilmTex,
					float2(
						i.uv.x * s + s * floor(_Time[1] * _FrameSpeed),
						i.uv.y)).r;
				c = lerp(c, fixed4(0, 0, 0, 1), (1-m) * _Amount);
				return c;
			}

			ENDCG
		}
	}
}