Best way to add a Normal Power Slider for Surface Shader?

Hey Guys,

I'm just wondering what the best/most accurate way is to create a Normal scale slider (similar to the Unity Standard shader one). Ideally one that can go from 0 - 3 or even more. I have tried a couple of different ways with mixed results. I have looked briefly at the way Unity does it in their shader but I didnt really understand how to replicate it.

Any help would be great!

Here are some examples on the methods I have tried.

Code (CSharp):

1. sampler2D _MainTex;
2.         sampler2D _BumpMap;
3.  
4.         struct Input {
5.             float2 uv_MainTex;
6.         };
7.  
8.         half _Glossiness;
9.         half _BumpScale;
10.         half _Metallic;
11.         fixed4 _Color;
12.         half3 _NormalDefault;
13.  
14.         void surf (Input IN, inout SurfaceOutputStandard o) {
15.             // Albedo comes from a texture tinted by color
16.             fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
17.             o.Albedo = c.rgb;
18.             // Metallic and smoothness come from slider variables
19.             o.Metallic = _Metallic;
20.             o.Smoothness = _Glossiness;
21.  
22.             //Method 1
23.             o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_MainTex) *_BumpScale);
24.  
25.             //Method 2
26.             //_NormalDefault = Half3(128, 128, 255) --found these values online
27.             o.Normal = lerp(_NormalDefault, UnpackNormal(tex2D(_BumpMap, IN.uv_MainTex)), _BumpScale);
28.  
29.  
30.             //fallback method
31.             o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_MainTex));
32.             //o.Normal = _NormalDefault;
33.             o.Alpha = c.a;
34.         }

 

UnityStandardUtils.cginc has the one that the Standard shaders use.

Code (CSharp):

1. half3 UnpackScaleNormal(half4 packednormal, half bumpScale)
2. {
3.     #if defined(UNITY_NO_DXT5nm)
4.         return packednormal.xyz * 2 - 1;
5.     #else
6.         half3 normal;
7.         normal.xy = (packednormal.wy * 2 - 1);
8.         #if (SHADER_TARGET >= 30)
9.             // SM2.0: instruction count limitation
10.             // SM2.0: normal scaler is not supported
11.             normal.xy *= bumpScale;
12.         #endif
13.         normal.z = sqrt(1.0 - saturate(dot(normal.xy, normal.xy)));
14.         return normal;
15.     #endif
16. }

The lerp method in your example can work as well, except your _NormalDefault value is for the values of an 8 bit normal map texture, not the actual tangent space normal direction which o.Normal expects and UnpackNormal() returns.

You could try:
o.Normal = lerp(half3(0.0, 0.0, 1.0), UnpackNormal(tex2D(_BumpMap, IN.uv_MainTex), _BumpScale);

 

Great Thanks that works , I must have missed that!