big question for a new shader guy...

Hi all,

I'm trying to figure out how to make a shader that makes an object seem partially translucent, and blurry. I don't want motion blur, because the object could be sitting still, I just want the edges to sort of "fuzz out" to the background.

Any ideas?

-T

 

Okay, here's what I've come up with so far. Its a modification to the x-ray shader. Instead of fading into/out of a standard color, it fades through a texture assigned to the object. It doesn't quite work the way I want, though.

Here's the code

Code (csharp):

1.  
2. Shader "XRay" {
3.     Properties {
4.         _Color ("Tint (RGB)", Color) = (1,1,1,1)
5.         _RampTex ("Facing Ratio Ramp (RGB)", 2D) = "white" {}
6.         _MainTex ("Main texture",2D) = "white" {}
7.     }
8.     Category {
9.         ZWrite Off
10.         Tags {"Queue"="Transparent"}
11.         Lighting On
12.         SubShader {
13.             Pass {
14.                 Blend One One
15.                
16.                 CGPROGRAM
17.                 // profiles arbfp1
18.                 // vertex vert
19.                
20.                 #include "UnityCG.cginc"
21.      
22.                 sampler2D _MainTex : register(s0);
23.                 struct v2f {
24.                     V2F_POS_FOG;
25.                     float4 uv : TEXCOORD0;
26.                     float2 uv1 :TEXCOORD1;
27.                 };
28.                
29.                 v2f vert (appdata_base v) {
30.                     v2f o;
31.                     PositionFog( v.vertex, o.pos, o.fog );
32.                     o.uv1 = TRANSFORM_UV(0);
33.  
34.                     float3 viewDir = normalize(ObjSpaceViewDir(v.vertex));
35.                    
36.                     o.uv.x = dot(viewDir, v.normal);
37.                     o.uv.y = 0.5;
38.                     o.uv.z = 0.0;
39.                     o.uv.w = 1.0;
40.                     return o;
41.                 }
42.                
43.                 ENDCG
44.                
45.                 SetTexture [_RampTex] {
46.                     constantColor[_Color] combine texture * constant
47.                 }
48.                 SetTexture [_MainTex] {
49.                     combine texture * previous, previous
50.                 }
51.             }
52.         }
53.     }
54. }
55.  

Try it out. The problem is, even the parts that are supposed to be "solid" aren't. Any ideas on why, or how to fix that issue?

Thanks,
-T

[/code]

 

That had an interesting effect. It makes it fade out to black where before it was transparent. I'll keep playing around with it (I'm still learning about shader programming), but any more insights that people might have would be very much appreciated.

-T

 

Alright, I figured out something that works:

Code (csharp):

1.  
2. Shader "XRay" {
3.     Properties {
4.         _Color ("Tint (RGB)", Color) = (1,1,1,1)
5.         _MainTex ("Main texture",2D) = "white" {}
6.     }
7.     Category {
8.         ZWrite Off
9.         Tags {"Queue"="Transparent"}
10.         Lighting Off
11.         SubShader {
12.             Pass {
13.                 // Blend One One
14.                 Blend SrcAlpha OneMinusSrcAlpha
15.                
16.                 CGPROGRAM
17.                 // profiles arbfp1
18.                 // vertex vert
19.                 //fragment frag
20.                 //fragmentoption ARB_fog_exp2
21.    
22.                 #include "UnityCG.cginc"
23.      
24.                 sampler2D _MainTex : register(s0);
25.                 struct v2f {
26.                     V2F_POS_FOG;
27.                     float2 uv1 :TEXCOORD1;
28.                     float3 color : COLOR0;
29.                     float alpha;
30.                 };
31.                
32.                 v2f vert (appdata_base v) {
33.                     v2f o;
34.                     PositionFog( v.vertex, o.pos, o.fog );
35.                     o.uv1 = TRANSFORM_UV(0);
36.                    
37.                     float3 viewDir = normalize(ObjSpaceViewDir(v.vertex));
38.                     o.alpha = dot(viewDir, v.normal) * dot(viewDir,v.normal);
39.                    
40.                     return o;
41.                 }
42.                
43.                 half4 frag(v2f i) : COLOR {
44.                     half4 texcol = tex2D(_MainTex, i.uv1);
45.                     return half4(texcol.rgb, i.alpha);
46.                 }
47.                
48.                 ENDCG
49.            
50.                 SetTexture [_MainTex] {
51.                     combine texture
52.                 }          
53.             }
54.         }
55.     }
56. }
57.  

Its frustrating working with a new language/paradigm...

Anyway, this gives me the fade-to-edges that I was talking about. It's not ideal (ideally, it would just sample that part of the screen, and do a radial blur...), and it uses a fragment program, but it's a start.

Does anyone have any insights into how to get this same effect without a fragment program?

Thanks,
-T

 

Okay, I'm going all the way with a grab texture, and doing a radial blur on what it gets. I know the radial blur algorithm, no problem, but I have an issue. When I compile my shader, I get a "profile does not support for statements" error. What profile does (that unity knows how to compile to)? Or do I have to un-roll the loop myself?

-T

 

Okay, good to know. Thanks! How, though, do I do an image effect that only applies to the area of the screen that a particular object is on, instead of the whole screen?

 

Dude. How did I not find that thread in all my searching?! This is exactly the sort of thing that I'm looking for (or at least a GREAT starting point for it). Thank you so much! Hopefully when I start to figure out more of this stuff, I can start contributing back.

Thanks again!