#lab renderer

Turns out Valve’s Lab Renderer doesn’t support particle lights so I had to implement a simple, crude, method of mimicking the effect. Only tested it with sparks but it works pretty well. Probably wouldn’t work for most other effects but that was never the intention.

So I like quite a few others doing VR stuff in unity have been using the Lab Renderer. For the most part I love the changes that it makes but the inability to change roughness does bug me and some artists that I know who have used it.

This image shows the difference between the Lab Renderer without my roughness change (on the right) and with my roughness change (on the left) where I picked a factor of 10. In the Lab Renderer, this is hard coded at 14 and gives extremely reflective surfaces to the point where you can get what look like individual pixels completely white but surrounded by black pixels. This can be seen at the back of the right image.

Basically my solution to this was to add a modifiable roughness. You could go and change the shader and hard code in another value but what if you want a different value for different shaders?

In order to achieve the same effect, follow the instructions below. I won’t paste copies of the code here as it is Copyright of Valve but the necessary changes are listed.

vr_standard.shader

Add 'g_flRoughnessFactor( "RoughnessFactor", Float ) = 14.0' below 'g_flReflectanceMax( "g_flReflectanceMax", Range( 0.0, 1.0 ) ) = 1.0'

vr_lighting.cginc

Add 'float g_flRoughnessFactor = 14.0;' below 'float g_flReflectanceMax = 1.0;' 

Change the second line of 'RoughnessEllipseToScaleAndExp' to 'o_vSpecularExponentOut.xy = exp2( pow( float2( 1.0, 1.0 ) - vRoughness.xy, float2( 1.5, 1.5 ) ) * float2( g_flRoughnessFactor, g_flRoughnessFactor ) ); // Outputs 1-16384'

ValveShaderGUI.cs

Add 'public static GUIContent roughnessFactorText = new GUIContent( "Roughness Factor", "" );' below the line ending 'new GUIContent( "Reflectance Max", "" );'

Add 'MaterialProperty roughnessFactor = null;' below 'MaterialProperty reflectanceMax = null;'

Add 'roughnessFactor = FindProperty( "g_flRoughnessFactor", props );' below 'reflectanceMax = FindProperty( "g_flReflectanceMax", props );'

Add 'm_MaterialEditor.ShaderProperty( roughnessFactor, Styles.roughnessFactorText.text, 2 );' at the end of the function ‘DoSpecularMetallicArea’

Add 'float flRoughnessFactor = material.GetFloat( "g_flRoughnessFactor" );' below float flReflectanceMax = material.GetFloat( "g_flReflectanceMax" );

Add 'material.SetFloat( "g_flRoughnessFactor", flRoughnessFactor );' below 'material.SetFloat( "g_flReflectanceBias", flReflectanceMin );'