Two Pass Standard Shader

I am trying to write a two pass standard shader. I have found examples with older shaders, I want to use Unity 5.4 beta and try to use the built-in shader to match all of the other objects in the scene. It is easy to break the standard shader, especially because I am not good with writing shaders to begin with. Usually I can find a shader, tweak a couple of things and I'm good.

I'm stuck and don't know where to start! I have narrowed down that what I probably want is a two pass shader where one pass is for front faces, and the other for back faces. The front faces I want to be rendered exactly as the standard shader. The back faces I want to use a transparent shader, either with an alpha value or a texture with an alpha.

Here is a screen shot of what I am after [Note the model has normals reversed, meaning the interior is where this is supposed to be viewed, but as I the viewer exits the interior, I want the exterior to be visible as a grid]:



Can someone explain to me, where would I put the second shader? Here is the standard shader I am trying to work with:

Spoiler: Standard Shader :

Shader "Standard"
{
Properties
{
_Color("Color", Color) = (1,1,1,1)
_MainTex("Albedo", 2D) = "white" {}

_Cutoff("Alpha Cutoff", Range(0.0, 1.0)) = 0.5

_Glossiness("Smoothness", Range(0.0, 1.0)) = 0.5
_GlossMapScale("Smoothness Scale", Range(0.0, 1.0)) = 1.0
[Enum(Metallic Alpha,0,Albedo Alpha,1)] _SmoothnessTextureChannel ("Smoothness texture channel", Float) = 0

[Gamma] _Metallic("Metallic", Range(0.0, 1.0)) = 0.0
_MetallicGlossMap("Metallic", 2D) = "white" {}

[ToggleOff] _SpecularHighlights("Specular Highlights", Float) = 1.0
[ToggleOff] _GlossyReflections("Glossy Reflections", Float) = 1.0

_BumpScale("Scale", Float) = 1.0
_BumpMap("Normal Map", 2D) = "bump" {}

_Parallax ("Height Scale", Range (0.005, 0.08)) = 0.02
_ParallaxMap ("Height Map", 2D) = "black" {}

_OcclusionStrength("Strength", Range(0.0, 1.0)) = 1.0
_OcclusionMap("Occlusion", 2D) = "white" {}

_EmissionColor("Color", Color) = (0,0,0)
_EmissionMap("Emission", 2D) = "white" {}

_DetailMask("Detail Mask", 2D) = "white" {}

_DetailAlbedoMap("Detail Albedo x2", 2D) = "grey" {}
_DetailNormalMapScale("Scale", Float) = 1.0
_DetailNormalMap("Normal Map", 2D) = "bump" {}

[Enum(UV0,0,UV1,1)] _UVSec ("UV Set for secondary textures", Float) = 0


// Blending state
[HideInInspector] _Mode ("__mode", Float) = 0.0
[HideInInspector] _SrcBlend ("__src", Float) = 1.0
[HideInInspector] _DstBlend ("__dst", Float) = 0.0
[HideInInspector] _ZWrite ("__zw", Float) = 1.0
}

CGINCLUDE
#define UNITY_SETUP_BRDF_INPUT MetallicSetup
ENDCG

SubShader
{
Tags { "RenderType"="Opaque" "PerformanceChecks"="False" }
LOD 300


// ------------------------------------------------------------------
// Base forward pass (directional light, emission, lightmaps, ...)
Pass
{
Name "FORWARD"
Tags { "LightMode" = "ForwardBase" }

Blend [_SrcBlend] [_DstBlend]
ZWrite [_ZWrite]

CGPROGRAM
#pragma target 3.0

// -------------------------------------

#pragma shader_feature _NORMALMAP
#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma shader_feature _EMISSION
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature ___ _DETAIL_MULX2
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature _ _SPECULARHIGHLIGHTS_OFF
#pragma shader_feature _ _GLOSSYREFLECTIONS_OFF
#pragma shader_feature _PARALLAXMAP

#pragma multi_compile_fwdbase
#pragma multi_compile_fog

#pragma vertex vertBase
#pragma fragment fragBase
#include "UnityStandardCoreForward.cginc"

ENDCG
}
// ------------------------------------------------------------------
// Additive forward pass (one light per pass)
Pass
{
Name "FORWARD_DELTA"
Tags { "LightMode" = "ForwardAdd" }
Blend [_SrcBlend] One
Fog { Color (0,0,0,0) } // in additive pass fog should be black
ZWrite Off
ZTest LEqual

CGPROGRAM
#pragma target 3.0

// -------------------------------------


#pragma shader_feature _NORMALMAP
#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature _ _SPECULARHIGHLIGHTS_OFF
#pragma shader_feature ___ _DETAIL_MULX2
#pragma shader_feature _PARALLAXMAP

#pragma multi_compile_fwdadd_fullshadows
#pragma multi_compile_fog


#pragma vertex vertAdd
#pragma fragment fragAdd
#include "UnityStandardCoreForward.cginc"

ENDCG
}
// ------------------------------------------------------------------
// Shadow rendering pass
Pass {
Name "ShadowCaster"
Tags { "LightMode" = "ShadowCaster" }

ZWrite On ZTest LEqual

CGPROGRAM
#pragma target 3.0

// -------------------------------------


#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma multi_compile_shadowcaster

#pragma vertex vertShadowCaster
#pragma fragment fragShadowCaster

#include "UnityStandardShadow.cginc"

ENDCG
}
// ------------------------------------------------------------------
// Deferred pass
Pass
{
Name "DEFERRED"
Tags { "LightMode" = "Deferred" }

CGPROGRAM
#pragma target 3.0
#pragma exclude_renderers nomrt


// -------------------------------------

#pragma shader_feature _NORMALMAP
#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma shader_feature _EMISSION
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature _ _SPECULARHIGHLIGHTS_OFF
#pragma shader_feature ___ _DETAIL_MULX2
#pragma shader_feature _PARALLAXMAP

#pragma multi_compile ___ UNITY_HDR_ON
#pragma multi_compile LIGHTMAP_OFF LIGHTMAP_ON
#pragma multi_compile DIRLIGHTMAP_OFF DIRLIGHTMAP_COMBINED DIRLIGHTMAP_SEPARATE
#pragma multi_compile DYNAMICLIGHTMAP_OFF DYNAMICLIGHTMAP_ON

#pragma vertex vertDeferred
#pragma fragment fragDeferred

#include "UnityStandardCore.cginc"

ENDCG
}

// ------------------------------------------------------------------
// Extracts information for lightmapping, GI (emission, albedo, ...)
// This pass it not used during regular rendering.
Pass
{
Name "META"
Tags { "LightMode"="Meta" }

Cull Off

CGPROGRAM
#pragma vertex vert_meta
#pragma fragment frag_meta

#pragma shader_feature _EMISSION
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature ___ _DETAIL_MULX2

#include "UnityStandardMeta.cginc"
ENDCG
}
}

SubShader
{
Tags { "RenderType"="Opaque" "PerformanceChecks"="False" }
LOD 150

// ------------------------------------------------------------------
// Base forward pass (directional light, emission, lightmaps, ...)
Pass
{
Name "FORWARD"
Tags { "LightMode" = "ForwardBase" }

Blend [_SrcBlend] [_DstBlend]
ZWrite [_ZWrite]

CGPROGRAM
#pragma target 2.0

#pragma shader_feature _NORMALMAP
#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma shader_feature _EMISSION
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature _ _SPECULARHIGHLIGHTS_OFF
#pragma shader_feature _ _GLOSSYREFLECTIONS_OFF
// SM2.0: NOT SUPPORTED shader_feature ___ _DETAIL_MULX2
// SM2.0: NOT SUPPORTED shader_feature _PARALLAXMAP

#pragma skip_variants SHADOWS_SOFT DIRLIGHTMAP_COMBINED DIRLIGHTMAP_SEPARATE

#pragma multi_compile_fwdbase
#pragma multi_compile_fog

#pragma vertex vertBase
#pragma fragment fragBase
#include "UnityStandardCoreForward.cginc"

ENDCG
}
// ------------------------------------------------------------------
// Additive forward pass (one light per pass)
Pass
{
Name "FORWARD_DELTA"
Tags { "LightMode" = "ForwardAdd" }
Blend [_SrcBlend] One
Fog { Color (0,0,0,0) } // in additive pass fog should be black
ZWrite Off
ZTest LEqual

CGPROGRAM
#pragma target 2.0

#pragma shader_feature _NORMALMAP
#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature _ _SPECULARHIGHLIGHTS_OFF
#pragma shader_feature ___ _DETAIL_MULX2
// SM2.0: NOT SUPPORTED shader_feature _PARALLAXMAP
#pragma skip_variants SHADOWS_SOFT

#pragma multi_compile_fwdadd_fullshadows
#pragma multi_compile_fog

#pragma vertex vertAdd
#pragma fragment fragAdd
#include "UnityStandardCoreForward.cginc"

ENDCG
}
// ------------------------------------------------------------------
// Shadow rendering pass
Pass {
Name "ShadowCaster"
Tags { "LightMode" = "ShadowCaster" }

ZWrite On ZTest LEqual

CGPROGRAM
#pragma target 2.0

#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON
#pragma skip_variants SHADOWS_SOFT
#pragma multi_compile_shadowcaster

#pragma vertex vertShadowCaster
#pragma fragment fragShadowCaster

#include "UnityStandardShadow.cginc"

ENDCG
}

// ------------------------------------------------------------------
// Extracts information for lightmapping, GI (emission, albedo, ...)
// This pass it not used during regular rendering.
Pass
{
Name "META"
Tags { "LightMode"="Meta" }

Cull Off

CGPROGRAM
#pragma vertex vert_meta
#pragma fragment frag_meta

#pragma shader_feature _EMISSION
#pragma shader_feature _METALLICGLOSSMAP
#pragma shader_feature _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
#pragma shader_feature ___ _DETAIL_MULX2

#include "UnityStandardMeta.cginc"
ENDCG
}
}


FallBack "VertexLit"
CustomEditor "StandardShaderGUI"
}

 

I am clueless when it comes to shaders but there is already a shader like this i think . If you look for MCS in the asset store there are a few MCS lite entries which are free and contain double sided standard shaders including a 2 pass one.Might be what you are looking for or give u a idea how to accomplish your goal?

 

Thanks, that helps a lot! I would never have found those. I think I can pick through this and figure it out. Shaders were already complicated, but the new Standard looks even more so, it's really hard to understand what it's doing, even with all the commenting...

 

Yea i tried playing around with shaders and failed big time I will probably have another stab at it after the trauma has faded a bit.