Shader works in Editor but not on iPhone

I am using the next script for a painting asset found on this website https://medium.com/@shahriyarshahrabi/mesh-texture-painting-in-unity-using-shaders-8eb7fc31221c .

As you render the faces of your mesh in the uv space of the mesh, you are reconstruction the islands one triangle at the time. On the edges of the island, it can be that due to underestimation the rasterizer doesn’t consider a pixel which is actually in the island. For these pixels, no pixel shader will be executed and you will be left over with a crease. (text and image taken form the website)



The basic idea is that every frame, after the paint texture has been updated, I run a shader over the entire texture, and using a filter and a pre baked mask of the uv islands, extend the islands outwards.

The problem is that it does not work on iPhone. There is no error, no weird coloring, it is like that script does not get applied. I am not sure where the problem is coming from..maybe the for loops or the command buffers used in c#.

Code (CSharp):

1. Shader "Unlit/FixIlsandEdges"
2. {
3.  
4.     SubShader
5.     {
6.         // =====================================================================================================================
7.         // TAGS AND SETUP ------------------------------------------
8.         Tags { "RenderType"="Opaque" }
9.         LOD 100
10.  
11.         Pass
12.         {
13.  
14.          
15.         // =====================================================================================================================
16.         // DEFINE AND INCLUDE ----------------------------------
17.             CGPROGRAM
18.             #pragma  vertex   vert
19.             #pragma  fragment frag
20.          
21.             #include "UnityCG.cginc"
22.  
23.             // =====================================================================================================================
24.             // DECLERANTIONS ----------------------------------
25.             struct appdata
26.             {
27.                 float4 vertex : POSITION;
28.                 float2 uv      : TEXCOORD0;
29.             };
30.  
31.             struct v2f
32.             {
33.                 float2 uv      : TEXCOORD0;
34.                 float4 vertex : SV_POSITION;
35.             };
36.  
37.                     sampler2D    _MainTex;
38.             uniform    float4        _MainTex_TexelSize;
39.                     sampler2D   _IlsandMap;
40.          
41.             // =====================================================================================================================
42.             // VERTEX FRAGMENT ----------------------------------
43.             v2f vert (appdata v)
44.             {
45.                 v2f o;
46.                 o.vertex = UnityObjectToClipPos(v.vertex);
47.                 o.uv     = v.uv;
48.                 return o;
49.             }
50.          
51.             fixed4 frag (v2f i) : SV_Target
52.             {
53.  
54.             fixed4 col = tex2D(_MainTex, i.uv);
55.             float map  = tex2D(_IlsandMap,i.uv);
56.          
57.             float3 average = col;
58.  
59.             if (map.x < 0.2) {                                    // only take an average if it is not in a uv ilsand
60.                 int n = 0;
61.                 average = float3(0., 0., 0.);
62.  
63.                 for (float x = -1.5; x <= 1.5; x++) {
64.                     for (float y = -1.5; y <= 1.5; y++) {
65.  
66.                         float3 c =  tex2D(_MainTex, i.uv + _MainTex_TexelSize.xy*float2(x, y));
67.                         float  m =  tex2D(_IlsandMap, i.uv + _MainTex_TexelSize.xy*float2(x, y));
68.  
69.                                n += step(0.1, m);
70.                          average += c * step(0.1, m);
71.  
72.                     }
73.                 }
74.  
75.                 average /= n;
76.             }
77.      
78.             col.xyz = average;
79.      
80.                 return col;
81.             }
82.             ENDCG
83.         }
84.     }
85. }

I've read somewhere that using tex2D in for loops is a big no no, so I changed that to a tex2Dlod but the same thing happens.

You can check out the Git project here https://github.com/IRCSS/TexturePaint/blob/master/Assets/Scripts/FixIlsandEdges.shader

I am completely lost on this one and google isn't very helpful. Thank you for any comments.

 

Try to remove step. Step is basically shortcut for if(a < b)... and iphones has some strange buggy behaviour with stacked branches.

 

@BattleAngelAlita I tried you suggestion but sadly it doesn't work.

 

Anyone? I am still trying to figure this out