Custom shaders work in Editor but no always on the Rift?

Hi,

I wonder if anyone can help. I was trying to find a way to overcome the last gen limitation of 4096x4096 texture resolution in Unity and found some code on line for a shader to split up into 4 parts to load in 4x 4096x4096 textures to display 1x 8192x8192 texture resolution. I know some will say why?! that's crazy who needs 8k texture etc but in this case I do.

    Shader "Custom/4-Part Texture" {  
        Properties {  
            _MainTex0 ("Base (RGB)", 2D) = "white" {}  
            //Added three more textures slots, one for each image  
            _MainTex1 ("Base (RGB)", 2D) = "white" {}  
            _MainTex2 ("Base (RGB)", 2D) = "white" {}  
            _MainTex3 ("Base (RGB)", 2D) = "white" {}  
        }  
        SubShader {  
            Tags { "RenderType"="Opaque" "LightMode" = "Vertex"}          
            LOD 200  
      
            CGPROGRAM  
            #pragma surface surf Lambert  
      
            sampler2D _MainTex0;  
            //Added three more 2D samplers, one for each additional texture  
            sampler2D _MainTex1;  
            sampler2D _MainTex2;  
            sampler2D _MainTex3;  
      
            struct Input {  
                float2 uv_MainTex0;  
            };  
      
            //this variable stores the current texture coordinates multiplied by 2  
            float2 dbl_uv_MainTex0;  
      
            void surf (Input IN, inout SurfaceOutput o) {  
      
                //multiply the current vertex texture coordinate by two  
                dbl_uv_MainTex0 = IN.uv_MainTex0*2;  
      
                //add an offset to the texture coordinates for each of the input textures  
                half4 c0 = tex2D (_MainTex0, dbl_uv_MainTex0 - float2(0.0, 1.0));  
                half4 c1 = tex2D (_MainTex1, dbl_uv_MainTex0 - float2(1.0, 1.0));  
                half4 c2 = tex2D (_MainTex2, dbl_uv_MainTex0);  
                half4 c3 = tex2D (_MainTex3, dbl_uv_MainTex0 - float2(1.0, 0.0));  
      
                //this if statement assures that the input textures won't overlap  
                if(IN.uv_MainTex0.x >= 0.5)  
                {  
                    if(IN.uv_MainTex0.y <= 0.5)  
                    {  
                        c0.rgb = c1.rgb = c2.rgb = 0;  
                    }  
                    else  
                    {  
                        c0.rgb = c2.rgb = c3.rgb = 0;  
                    }  
                }  
                else  
                {  
                    if(IN.uv_MainTex0.y <= 0.5)  
                    {  
                        c0.rgb = c1.rgb = c3.rgb = 0;  
                    }  
                    else  
                    {  
                        c1.rgb = c2.rgb = c3.rgb = 0;  
                    }  
                }  
      
                //sum the colors and the alpha, passing them to the Output Surface 'o'  
                o.Albedo = c0.rgb + c1.rgb + c2.rgb + c3.rgb;  
                o.Alpha = c0.a + c1.a + c2.a + c3.a ;  
            }  
            ENDCG  
        }  
        FallBack "Diffuse"  
    } 

Code from here - http://www.41post.com/4416/programming/unity3d-using-textures-larger-than-4096x4096

I have the shader working great in the editor and whilst going into Game mode. I can see the giant leap in texture resolution quality but yet again when I build and run on the Rift, the shader breaks. I've that this can happen with allot of custom shaders and I'm not sure why.







I've also had this happen when testing the MattShadow shader from Kragh http://forum.unity3d.com/threads/14438-Matte-Shadow. Fine in Editor and Game but dosn't display correctly on the Rift.

Can anyone help on this?

Thanks,
Lee