Unity3D shader scrabble

X-RAY Effect

  		/*
            CGPROGRAM 
            #pragma vertex vert
			#pragma fragment frag
            #include "UnityCG.cginc" 

			uniform sampler2D _Ramp;
			uniform half4 _Color;

            struct v2f {
                float4 pos : SV_POSITION;
                float4 uv : TEXCOORD0;
            };
            
            v2f vert (appdata_base v) {
                v2f o;
                o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                float3 viewDir = normalize(ObjSpaceViewDir(v.vertex));
                o.uv = float4( dot(viewDir,v.normal), 0.5, 0.0, 1.0 );
                return o;
            }

			half4 frag(v2f v) : COLOR {
				return tex2D(_Ramp, v.uv.xy) * _Color;
			}
            ENDCG 
			*/

Shader "XRay" {
    Properties {
        _MainTex ("Main (RGB)", 2D) = "white" {}
        _Ramp ("Ramp (RGB)", 2D) = "white" {}
        _Color ("Tint (RGB)", Color) = (1,1,1,1)
    }
    SubShader {
        Tags { "Queue"="Geometry+1" "RenderType"="Opaque" }
        Pass {
            blend one one
            ztest greater 
            zwrite off

            settexture[_Ramp] {
                combine texture
            }
        }
        Pass {
            settexture[_MainTex] {
                combine texture
            }
        }
    }
    Fallback Off
}

// *****************
// compute luminance
// *****************
float3 rgb2lum = float3(0.30, 0.59, 0.11);

luminance = dot(col.rgb, rgb2lum);

// *****************
// TRANSFORM_TEX
// *****************

define TRANSFORM_TEX(tex,name) (tex.xy * name##_ST.xy + name##_ST.zw)