Why does this simple additive shader draw as non-additive?

I have this simple shader:

Code (csharp):

1.  
2. Shader "Swirly Glow Outline"
3. {
4.     Properties
5.     {
6.         _Color ("Main Color", Color) = (1,1,1,1)
7.         _MainTex ("Base (RGB)", 2D) = "white" {}
8.     }
9.    
10.     SubShader
11.     {
12.         Tags
13.         {
14.             "RenderType" = "Transparent"
15.             "Queue" = "Transparent"
16.         }
17.         Lighting Off
18.         ZWrite Off
19.         Cull Off
20.         Blend One One
21.        
22.         CGPROGRAM
23.             #pragma target 3.0
24.             #pragma surface surf BlinnPhong vertex:vert alpha
25.             #include "UnityCG.cginc"
26.            
27.             sampler2D _MainTex;
28.             float4 _Color;
29.            
30.             void vert (inout appdata_full v)
31.             {
32.                 v.texcoord = float4(sin(_Time.x), _Time.x, 0, 0)*1.5;
33.              }
34.            
35.             struct Input
36.             {
37.                 float2 uv_MainTex;
38.                 float4 color:COLOR;
39.                 float4 screenPos;
40.             };
41.            
42.             void surf (Input IN, inout SurfaceOutput o)
43.             {  
44.                 IN.uv_MainTex += IN.screenPos*4;
45.                 half tex = tex2D(_MainTex, IN.uv_MainTex).r;
46.                 o.Albedo = _Color.rgb;
47.                 o.Alpha = 1;
48.             }
49.         ENDCG
50.     }
51.     Fallback "Particles/Additive"
52. }

which should result in additive blended, but for some reason shows up as normal blending, like so:



The yellow outline shape should be additive, but it's not. I'm probably missing something really obvious, but I'm damned if I can see it. Can anyone shed some light on this?

 

I think the surface shader auto-generates the blend thing due to the pragmas you used. See here: http://answers.unity3d.com/questions/122449/how-to-set-up-additive-blending-on-a-surface-shade.html

 

Ah, thanks Imaginary Human. It seems the alpha pragma specifically overrides the blending mode. That's a bit of a nuisance.