DrawMesh / Stencil / RendureTexture topic

Hello!

In my slot game I am using DrawMesh calls to render thick win lines like shown in the screenshot. First I am rendering the background of the boxes with stencil write on, then I render the boxes with stencil write on, then I am rendering the lines with stencil testing, so the lines get not rendered where the boxes are. ( see screenshot )

The problem is that I have no control over the z position of the win lines. In the frame debugger they always are rendered at the end of the camera render loop job. The z values in my meshes are ignored. I played around with zwrite on/off in the shaders, different queues but the result will always be the same: my lines will be the last steps render jobs.

I tried to render the winlines into a RenderTexture and display that texture as sprite. That does not work because the RenderTexture does not support stencil operations ( RenderTexture. SupportsStencil returns false for my render texture, and true for main screen )

I want to have other sprites rendered in front of the winlines, but the lines need to rendered by the same camera, because I am using a post effects to blur the screen in some situations when I display overlay windows.

The shader I use for writing to stencil looks like this:

 Shader "Zentronic/Color/MaskStencil" 
 {
      Properties
      {
         [PerRendererData] _Color ("Main Color", Color) = (1,1,1,1)
         _Stencil ("Stencil ID", Float) = 2
     }
     
     SubShader 
     {
         Tags 
         { 
             //"RenderType"      = "Transparent"
             //"Queue"      = "Transparent" 
             "IgnoreProjector" = "True"
             "ForceNoShadowCasting"  = "True"
          }
      
         Pass 
         {
             ZWrite On
               Cull Off
             Lighting Off
             Blend One OneMinusSrcAlpha
             ColorMask 0
                          
             Stencil 
             {
                     Ref [_Stencil]
                     Comp equal
                     Pass decrWrap 
                     Fail keep 
                 }
                
             CGPROGRAM
             
                 #pragma vertex vert_shader
                 #pragma fragment frag_shader
                 #include "UnityCG.cginc"
 
                 fixed4 _Color;
 
                 struct appdata_t 
                 {
                     float4 vertex : POSITION;
                     fixed4 color : COLOR;
                 };
 
                 struct v2f 
                 {
                     float4 vertex : SV_POSITION;
                     fixed4 color : COLOR;
                 };
                   
                 v2f vert_shader (appdata_t v)
                 {
                     v2f o;
                     o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                     o.color = v.color;
                     return o;
                 }
                 
                 fixed4 frag_shader (v2f i) : COLOR
                 {
                     i.color.rgb*=i.color.a;
                     return i.color;
                 }
                 
             ENDCG
         }
     }
 }

the other shader that renders the lines looks like so:

 Shader "Zentronic/Color/TestStencil" 
 {
     Properties
      {
         _Stencil ("Stencil ID", Float) = 2
     }
 
     SubShader 
     {
         Tags 
         { 
             "IgnoreProjector"     = "True"
             "ForceNoShadowCasting"  = "True"
          }
      
         Pass 
         {
             Blend One OneMinusSrcAlpha
             ZWrite On
               Cull Off
             Lighting Off
              
             Stencil 
             {
                     Ref [_Stencil]
                     Comp equal
                     Pass keep 
                     Fail keep 
                 }
                
             CGPROGRAM
             
                 #pragma vertex vert
                 #pragma fragment frag
                 #include "UnityCG.cginc"
 
                 struct appdata_t 
                 {
                     float4 vertex : POSITION;
                     fixed4 color : COLOR;
                 };
 
                 struct v2f 
                 {
                     float4 vertex : SV_POSITION;
                     fixed4 color : COLOR;
                 };
                   
                 v2f vert (appdata_t v)
                 {
                     v2f o;
                     o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                     o.color = v.color;
                     return o;
                 }
                 
                 fixed4 frag (v2f i) : COLOR
                 {
                     i.color.rgb*=i.color.a;
                      return i.color;
                 }
                 
             ENDCG
         }
     }
 }

So my questions are

1) How can I get control of z ordering of my DrawMesh calls ?

2) Can anyone here figure out how to solve this scenario ( perhaps with MeshFilter / Mesh Renderer ) and point me in the right direction how to implement this.

3) Can anyone figure out a better solution to render those boxes/lines without stencil operations ? ( This would make the render texture aproach possible )

Thank you in advance for your help and thoughts!

[1]: /storage/temp/81238-bildschirmfoto-2016-10-31-um-142016.png