Shader won't compile on Linux

Unity Engine
1

I have a simple shader that worked fine on Unity 4 but now fails to compile in Unity 5, in Linux only.

A user said they were able to make it work by creating an Nvidia Application Profile and setting
GLIgnoreGLSLExtReqs=true. When they do this, there is no problem.

I’m a bit stumped, can anyone help? Why doesn’t the shader compile on Linux?

Shader copied below. Thanks in advance.

Shader "Custom/Rain overlay"
{
    Properties
    {
        _Color ("Lerping color", Color) = (1,1,1)
        _TuningColor ("Tuning color", Color) = (1,1,1)
        _MainTex ("Overlay texture", 2D) = ""
        _MainTex2 ("Overlay texture 2", 2D) = ""
    }

    SubShader
    {
        Tags
        {
            "RenderType"="Transparent"
            "Queue"="Transparent+201" //After lighting overlay and weather overlay double
            "IgnoreProjector"="True"  
        }

        Lighting Off
        ZWrite Off
        Blend SrcAlpha OneMinusSrcAlpha

        Pass
        {
            //Do not render indoors
            //Check for the first bit (the indoor mask) of the stencil being set
            //Note that this must render BEFORE sunshadows otherwise they will set the indoors bit
            Stencil
            {
                Ref 1
                ReadMask 1
                Comp NotEqual
                Pass Keep
            }

            SetTexture [_MainTex]
            {
                combine texture
            }
      
            SetTexture [_MainTex2]
            {
                combine previous + texture
            }
          
            SetTexture [_]
            {
                constantColor [_TuningColor]
                Combine previous * constant
            }

            SetTexture [_]
            {
                constantColor [_Color]
                Combine previous * constant DOUBLE
            }
        }
    }
}
2

This did work in Unity 4, what might have made it start failing?

3

Ok, I solved it by just reimplementing the shader with a CGPROGRAM. Meh.

4

A reason why this shader did work with Unity 4 and might not with Unity 5 is Unity 5 no longer supports fixed function shaders… not directly at least. Instead of making all fixed function shaders suddenly stop working shaders written using fixed function syntax generate a vertex / fragment shader that is what actually gets used to render. I’ve noticed this conversion is not perfect, and doesn’t always generate the best shaders. You can see the generated shader by selecting the shader in the project view and clicking on the show generated button. This works for both fixed function and surface shaders as they both generate a vertex / fragment shader that gets used for actual rendering.

That doesn’t really explain why this particular shader didn’t work, but it should at least give you an understanding of what changed.