Trying to implement specularity in my shader, but getting apparent type mismatches

Questions & Answers
1

I am brand new to writing shaders, so I am mostly copy+pasting from examples at this point. But I successfully implemented a rim lighting shader, and a rim lighting shader that takes into account a bump map. However, I am getting unexpected type-mismatch errors when I try to implement specularity.

Material doesn't have a color property '_SpecColor'
UnityEditor.MaterialEditor:OnSelectedShaderPopup(String, Shader)
Material doesn't have a float or range property '_Shininess'
UnityEditor.MaterialEditor:OnSelectedShaderPopup(String, Shader)
Material doesn't have a color property '_RimColor'
UnityEditor.MaterialEditor:OnSelectedShaderPopup(String, Shader)
Material doesn't have a float or range property '_RimPower'
UnityEditor.MaterialEditor:OnSelectedShaderPopup(String, Shader)

Here is the (incomplete) code.

Shader "Falloff/FalloffSpecular" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 1)
		_Shininess ("Shininess", Range (0.01, 1)) = 0.078125
		_RimColor ("Rim Color", Color) = (0.26,0.19,0.16,0.0)
		_RimPower ("Rim Power", Range(0.5,8.0)) = 3.0
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200
		
		CGPROGRAM
		#pragma surface surf BlinnPhong

		sampler2D	_MainTex;
		float4		_SpecColor;
		half		_Shininess;	
		float4		_RimColor;
		float		_RimPower;


		struct Input {
			float2 uv_MainTex;
			float3 viewDir;
		};

		void surf (Input IN, inout SurfaceOutput o) {
			half4 c = tex2D (_MainTex, IN.uv_MainTex);
			o.Albedo = c.rgb;
			o.Alpha = c.a;
			half rim = 1.0 - saturate(dot (normalize(IN.viewDir), o.Normal));
			o.Emission = _RimColor.rgb * pow (rim, _RimPower);

		}
		ENDCG
	} 
	FallBack "Specular"
}
2

1.) The first thing to know about writing shaders is that the error messages are often very unhelpful :wink:

2.) The actual proplem is that you are redeclaring _SpecColor. This is already defined in Lighting.cginc (since it is used in the BlinnPhong lighting function), so try removing line 17 from your code (but keep it in the Properties block):
float4 _SpecColor;