Shader "Crayon Shaders/SimpleCrayonShader"
{
	Properties
	{
		[Header(Color Behaviour)] [Space]
		_Color("Color Tint", Color) = (1,1,1,1)
		_Brightness("Brightness", Range(0,5)) = 1
		_BaseTex("Base Texture", 2D) = "white" {}

		[Header(Crayon Overlay Behaviour)][Space]
		_CrayonTex("Crayon Texture", 2D) = "white" {}
		_CrayonTransparency("Crayon Transparency", Range(0,1)) = 1

		[Header(Rim Behaviour)][Space]
		_RimColor("Rim Color", Color) = (1,1,1,1)
		_RimPower("Rim Power", Range(0.5, 8.0)) = 5.0

		[Header(Distortion Behaviour)][Space]
		_NoiseTex("Noise Texture", 2D) = "white" {}
		_Period("Period", Range(0,50)) = 0.4
		_Magnitude("Magnitude", Range(0,0.05)) = 0.0007
		_Offset("Offset", Range(0,10)) = 0
	}

		SubShader
		{
		Tags{ "RenderType" = "Opaque" }
		LOD 400

		CGPROGRAM
		#pragma surface surf Toon
		#pragma target 3.0

		sampler2D _BaseTex;
		sampler2D _CrayonTex;
		sampler2D _RampTex;
		sampler2D _NoiseTex;
		half _CrayonTransparency, _Brightness, _RimPower, _Period, _Magnitude, _Offset;
		fixed4 _Color, _RimColor;

		half4 LightingToon(SurfaceOutput s, half3 lightDir, half atten)
		{
			half NdotL = dot(s.Normal, lightDir);
			NdotL = tex2D(_RampTex, fixed2(NdotL, 0.5));

			fixed4 c;
			c.rgb = s.Albedo * _LightColor0.rgb * NdotL * atten;
			c.a = s.Alpha;
			return c;
		}

		half JitterEffect(half x, half m, half M, half period)
		{
			half escursion = M - m;
			half coefficient = 3.1415 * 2.0 / period;
			half result = (escursion / 2.0 * (1.0 + sin(x * coefficient)) + m);
			return result;
		}

		struct Input {
			float2 uv_BaseTex;
			float2 uv_CrayonTex;
			float2 uv_NoiseTex;
			float3 viewDir;
		};

		void surf(Input IN, inout SurfaceOutput o) {
			fixed4 noise = tex2D(_NoiseTex, IN.uv_NoiseTex);

			half displacement =
				JitterEffect
				(
					half(_Time[1]) + (noise.xy) * _Offset,
					half(-_Magnitude),
					half(_Magnitude),
					half(_Period)
				);

			half4 base = tex2D(_BaseTex, IN.uv_BaseTex) * _Color * _Brightness;
			half4 crayon = tex2D(_CrayonTex, IN.uv_CrayonTex + displacement) * _CrayonTransparency;
			o.Albedo = lerp(base.rgb, crayon.rgb, crayon.a);

			half rim = 1.0 - saturate(dot(normalize(IN.viewDir), o.Normal));
			o.Emission = _RimColor.rgb * pow(rim, _RimPower);
		}
		ENDCG
	}
}