Make shader Specular Only

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1

I’m trying to make a shader specular only with bumps and everything to fake the light reflection on water. I’ve been using particles to fake the color of the water and the soft edges so I want the whole shader to be invisible except for the specular.

Here’s what the shader looks like now, which is pretty much just a modified AlphaBumpedSpec basic shader in Unity :

Shader "Water/CustomWaterShader" {
Properties {
	_Color ("Main Color", Color) = (1,1,1,1)
	_SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 0)
	_Shininess ("Shininess", Range (0.01, 1)) = 0.078125
	_MainTex ("Base (RGB) TransGloss (A)", 2D) = "white" {}
	_BumpMap ("Normalmap", 2D) = "bump" {}
	_BumpMap2 ("Normalmap", 2D) = "bump" {}
}

SubShader {
	Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
	LOD 400
	
	
CGPROGRAM
#pragma surface surf BlinnPhong alpha

sampler2D _MainTex;
sampler2D _BumpMap;
sampler2D _BumpMap2;
fixed4 _Color;
half _Shininess;

struct Input {
	float2 uv_MainTex;
	float2 uv_BumpMap;
	float2 uv_BumpMap2;
};

void surf (Input IN, inout SurfaceOutput o) {
	fixed4 tex = tex2D(_MainTex, IN.uv_MainTex);
	o.Albedo = tex.rgb * _Color.rgb;
	o.Alpha = tex.a * _Color.a;
	o.Gloss = 50;
	o.Specular = _Shininess;
	o.Normal = UnpackNormal(tex2D(_BumpMap , IN.uv_BumpMap)/2 + tex2D(_BumpMap2 , IN.uv_BumpMap2)/2);
}
ENDCG
}

FallBack "Transparent/VertexLit"
}

So, is there an easy way to change this shader into a specular only shader?

2

You can achieve a transparency effect by using GrabPass to grab what the camera rendered before that object. Your full shader should look something like this:

Shader "Water/CustomWaterShader" {
Properties {
_Color ("Main Color", Color) = (1,1,1,1)
_SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 0)
_Shininess ("Shininess", Range (0.01, 1)) = 0.078125
_MainTex ("Base (RGB) TransGloss (A)", 2D) = "white" {}
_BumpMap ("Normalmap", 2D) = "bump" {}
_BumpMap2 ("Normalmap", 2D) = "bump" {}
}
 
SubShader {
Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
LOD 400
GrabPass{"_ScreenTex"}
 
CGPROGRAM
#pragma surface surf BlinnPhong alpha
 
sampler2D _MainTex;
sampler2D _BumpMap;
sampler2D _ScreenTex;
sampler2D _BumpMap2;
fixed4 _Color;
half _Shininess;
 
struct Input {
float2 uv_MainTex;
float2 uv_BumpMap;
float2 uv_BumpMap2;
float4 screenPos;
};
 
void surf (Input IN, inout SurfaceOutput o) {
fixed4 tex = tex2D(_MainTex, IN.uv_MainTex);
fixed4 bg = tex2D(_ScreenTex,IN.screenPos.xy/IN.screenPos.w);
o.Albedo = bg.rgb*tex.rgb * _Color.rgb;
o.Alpha = bg.a*tex.a * _Color.a;
o.Gloss = 50;
o.Specular = _Shininess;
o.Normal = UnpackNormal(tex2D(_BumpMap , IN.uv_BumpMap)/2 + tex2D(_BumpMap2 , IN.uv_BumpMap2)/2);
}
ENDCG
}
 
FallBack "Transparent/VertexLit"
}

Feel free to change o.Albedo = bg.rgb*tex.rgb * _Color.rgb; to whatever suits you best.