Why does this shader work on iOS devices with Metal API but not with OpenGL ?

I have a simple shader I use to draw transparent highlights. It was working on any device when I was still using Unity 4.x, but since I upgraded to Unity 5.x, it doesn't work with iOS devices running OpenGL ES 2/3. It's fine though on devices running Metal.

Code (CSharp):

1. Shader "Lines/Colored Blended" {
2.     SubShader {
3.         Tags { "Queue" = "Transparent" }
4.         Pass {
5.             BindChannels { Bind "Color",color }  
6.      
7.             Blend SrcAlpha OneMinusSrcAlpha
8.             ZWrite Off
9.             //ZTest LEqual
10.             Cull Off
11.             Fog { Mode Off }
12.        }
13.     }
14. }

Do you guys have an idea ?

 

Fixed-function shader support has been partially removed from Unity 5.

https://unity3d.com/unity/whats-new/unity-5.0

 

Anyone knows how I could rewrite this shader using vertex & fragment ? I have no knowledge with this.

 

Like this:

Code (CSharp):

1. Shader "Custom/TransparentVertexColor" {
2.     SubShader {
3.         Pass {
4.             Tags{"Queue"="Transparent"}
5.             Blend SrcAlpha OneMinusSrcAlpha
6.             Cull Off
7.             ZWrite Off
8.             CGPROGRAM
9.             #pragma vertex vert
10.             #pragma fragment frag
11.  
12.             #include "UnityCG.cginc"
13.  
14.             struct v2f {
15.                 float4 pos:SV_POSITION;
16.                 float4 color:COLOR;
17.             };
18.  
19.             v2f vert(appdata_full v) {
20.                 v2f o;
21.                 o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
22.                 o.color = v.color;
23.                 return o;
24.             }
25.  
26.             fixed4 frag(v2f i) : SV_Target {
27.                
28.                 return i.color;
29.             }
30.  
31.             ENDCG
32.         }
33.     }
34. }

You need appdata_full to get your vertex color, which you need to pass from your vertex shader to your fragment shader for rendering. Also added the transparency stuff.

This is what the old fixed function bind does.