Jul
3
2016

Fake Tube Light Shader

An article by mgear

fakelinelight

Tried to test idea about tube lights (or “line light”), by using custom lighting in shader,
you could sample the light several times from different positions/angles,
so that it looks like the light is not just a single point. (not really working here properly yet, but kind of gives the effect, so it might be possible)

Source: *Light direction is animated in shader to show the effect

	Shader "Custom/FakeTubeishLight"
	{
	Properties
	{
	_MainTex ("Texture", 2D) = "white" {}
	}
	SubShader
	{
	Tags { "RenderType"="Opaque" }
	LOD 100
	CGPROGRAM
	#pragma surface surf SimpleSpecular

	half4 LightingSimpleSpecular (SurfaceOutput s, half3 lightDir, half3 viewDir, half atten) {

	half4 c = half4(0,0,0,0);

	int steps = 16;

	// sample light many times with different values
	for(int i=0;i<steps;i++)
	{

	half3 l = lerp(half3(1,1,i),half3(i,1,1),fmod(_Time.x*10,1));
	half3 h = normalize (lightDir*l + viewDir);
	half diff = max (0, dot (s.Normal, lightDir*l));
	float nh = max (0, dot (s.Normal, h));
	float spec = pow (nh, 10.0);

	c.rgb += (s.Albedo * _LightColor0.rgb * diff + _LightColor0.rgb * spec) * atten;
	}

	c.rgb /=steps;

	c.a = s.Alpha;
	return c;
	}


	struct Input {
	float2 uv_MainTex;
	};

	sampler2D _MainTex;

	void surf (Input IN, inout SurfaceOutput o) {
	o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
	}
	ENDCG
	}
	}