Simple shader question...

Category { Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" } Blend SrcAlpha One AlphaTest Greater .01 Blend SrcAlpha OneMinusSrcAlpha ColorMask RGB Cull Off Lighting Off ZWrite Off Fog { Mode Off } BindChannels { Bind "Color", color Bind "Vertex", vertex Bind "TexCoord", texcoord }

 // ---- Fragment program cards
 SubShader {
     Pass {

         CGPROGRAM
         #pragma vertex vert
         #pragma fragment frag
         #pragma fragmentoption ARB_precision_hint_fastest
         #pragma multi_compile_particles

         #include "UnityCG.cginc"

         sampler2D _MainTex;
         float4 _TintColor;

         struct appdata_t {
             float4 vertex : POSITION;
             float4 color : COLOR;
             float2 texcoord : TEXCOORD0;
         };

         struct v2f {
             float4 vertex : POSITION;
             float4 color : COLOR;
             float2 texcoord : TEXCOORD0;
             #ifdef SOFTPARTICLES_ON
             float4 projPos : TEXCOORD1;
             #endif
         };

         float4 _MainTex_ST;

         v2f vert (appdata_t v)
         {
             v2f o;
             o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
             #ifdef SOFTPARTICLES_ON
             o.projPos = ComputeScreenPos (o.vertex);
             COMPUTE_EYEDEPTH(o.projPos.z);
             #endif
             o.color = v.color;
             o.texcoord = TRANSFORM_TEX(v.texcoord,_MainTex);
             return o;
         }

         sampler2D _CameraDepthTexture;
         float _InvFade;

         half4 frag (v2f i) : COLOR
         {
             #ifdef SOFTPARTICLES_ON
             float sceneZ = LinearEyeDepth (tex2Dproj(_CameraDepthTexture, UNITY_PROJ_COORD(i.projPos)).r);
             float partZ = i.projPos.z;
             float fade = saturate (_InvFade * (sceneZ-partZ));
             i.color.a *= fade;
             #endif

             return 2.0f * i.color * _TintColor * tex2D(_MainTex, i.texcoord);
         }
         ENDCG 
     }
 }   

 // ---- Dual texture cards
 SubShader {
     Pass {
         SetTexture [_MainTex] {
             constantColor [_TintColor]
             combine constant * primary
         }
         SetTexture [_MainTex] {
             combine texture * previous DOUBLE
         }
     }
 }

 // ---- Single texture cards (does not do color tint)
 SubShader {
     Pass {
         SetTexture [_MainTex] {
             combine texture * primary
         }
     }
 }

} }