Thermal Effect on Unity Shader

TermalRed.shader

Shader "Custom/TermalRed" {
	Properties {
		_NormalTex("Normal Texture",2D) = "white" {}
		_DistanceFadeOut("DistanceFadeOut",Range(0,3)) = 0
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		
		LOD 200

		CGPROGRAM
		// Physically based Standard lighting model, and enable shadows on all light types
		#pragma surface surf Lambert noambient

		// Use shader model 3.0 target, to get nicer looking lighting
		#pragma target 3.0

		sampler2D _NormalTex;
		float _DistanceFadeOut;

		struct Input {
			float2 uv_NormalTex;
			float3 viewDir;
			//float3 worldPos;
		};


		void surf (Input IN, inout SurfaceOutput o) {
			o.Normal = UnpackNormal(tex2D(_NormalTex,IN.uv_NormalTex));
			float lightOpacity = dot(IN.viewDir,o.Normal);
			lightOpacity = pow(lightOpacity,2);
			o.Emission = float3(max(1-_DistanceFadeOut,0),max(0,lightOpacity-_DistanceFadeOut),max(0,0.5-lightOpacity));
		}
		ENDCG
	}
	FallBack "Diffuse"
}