Alternative Screen Space Ambient Occlusion (SSAO) Shader

I saw an article in Gamedev.net about a shader for SSAO
http://www.gamedev.net/reference/programming/features/simpleSSAO/

I'm wondering if this can be used in the free version of Unity as the SSAO shader that comes with Unity requires Pro.

The code unfortunately, is in HLSL. I hardly know cg or GLSL in the first place, so I'm having trouble trying to convert it to cg.

Code (csharp):

1.  
2. sampler g_buffer_norm;
3. sampler g_buffer_pos;
4. sampler g_random;
5. float random_size;
6. float g_sample_rad;
7. float g_intensity;
8. float g_scale;
9. float g_bias;
10.  
11. struct PS_INPUT
12. {
13.  float2 uv : TEXCOORD0;
14. };
15.  
16. struct PS_OUTPUT
17. {
18.  float4 color : COLOR0;
19. };
20.  
21. float3 getPosition(in float2 uv)
22. {
23.  return tex2D(g_buffer_pos,uv).xyz;
24. }
25.  
26. float3 getNormal(in float2 uv)
27. {
28.  return normalize(tex2D(g_buffer_norm, uv).xyz * 2.0f - 1.0f);
29. }
30.  
31. float2 getRandom(in float2 uv)
32. {
33.  return normalize(tex2D(g_random, g_screen_size * uv / random_size).xy * 2.0f - 1.0f);
34. }
35.  
36. float doAmbientOcclusion(in float2 tcoord,in float2 uv, in float3 p, in float3 cnorm)
37. {
38.  float3 diff = getPosition(tcoord + uv) - p;
39.  const float3 v = normalize(diff);
40.  const float d = length(diff)*g_scale;
41.  return max(0.0,dot(cnorm,v)-g_bias)*(1.0/(1.0+d))*g_intensity;
42. }
43.  
44. PS_OUTPUT main(PS_INPUT i)
45. {
46.  PS_OUTPUT o = (PS_OUTPUT)0;
47.  
48.  o.color.rgb = 1.0f;
49.  const float2 vec[4] = {float2(1,0),float2(-1,0),
50.             float2(0,1),float2(0,-1)};
51.  
52.  float3 p = getPosition(i.uv);
53.  float3 n = getNormal(i.uv);
54.  float2 rand = getRandom(i.uv);
55.  
56.  float ao = 0.0f;
57.  float rad = g_sample_rad/p.z;
58.  
59.  //**SSAO Calculation**//
60.  int iterations = 4;
61.  for (int j = 0; j < iterations; ++j)
62.  {
63.   float2 coord1 = reflect(vec[j],rand)*rad;
64.   float2 coord2 = float2(coord1.x*0.707 - coord1.y*0.707, coord1.x*0.707 + coord1.y*0.707);
65.  
66.   ao += doAmbientOcclusion(i.uv,coord1*0.25, p, n);
67.   ao += doAmbientOcclusion(i.uv,coord2*0.5, p, n);
68.   ao += doAmbientOcclusion(i.uv,coord1*0.75, p, n);
69.   ao += doAmbientOcclusion(i.uv,coord2, p, n);
70.  }
71.  ao/=(float)iterations*4.0;
72.  //**END**//
73.  
74. //Do stuff here with your occlusion value “ao”: modulate ambient lighting, write it to a buffer for later //use, etc.
75.  return o;
76. }
77.  

 

I see, thanks for clearing that up for me.

 

Hello ! were u able to convert this into CG ?