GPU???Shader?????????????????

??

????GPU???Shader??????????????

???????????4??

??????

?GPU Gems?1~3??GPU Pro?1~7???GPU Zen??????????11?????�GPU?????�???????????????????????????????????????????????????????????????????????Trick??????????????????????????????


??????????

?????????�GPU?????�11????????GPU Gems 1????????????????GPU???Shader?????????????????1?5????

PS:?????????????????????????????GitHub??�?GPU Gems 1???????????�??�???????????????????????????

?????????

�????????Realistic Skin Rendering?

�??????Subsurface Scattering?

�??????Ambient Occlusion?

�?????Real-Time Glow?

�??????Shadow Rendering?

�???????Perspective Shadow Maps?

�????????????Managing Visibility for Per-Pixel Lighting?

�??BRDF?Spatial BRDFs?

�????????Image-Based Lighting,IBL?

�?????Texture Bombing?

�?????Color Controls?

�???Depth of Field?

�??????High-Dynamic-Range,HDR?

???????????4?????????????

???GitHub??

????????GitHub????????????

???MarkDown????????????????????????????????GitHub??????????????????????????????????Git???????????????????????????GitHub?Repo????

????GitHub???????

QianMo/Game-Programmer-Study-Notesgithub.com

??�??????Highlight

??????????????????????????????????????GPUGems 1???????????�???????

?????????????????????????�?????????Real-Time

Glow?�????????????�???????Real-Time Glow?�?

???????????????????

�????????????????Effective Water Simulation from Physical

Models?

�??Dawn Demo???????Skin in the Dawn Demo?

�???????????????Rendering Countless Blades of Waving Grass?

�?????????????Real-Time Approximations to Subsurface Scattering?

�????????Ambient Occlusion?

�???????Real-Time Glow?

?????????????????

�?????????Rendering Water Caustics?

�??Dawn Demo?????Animation in the"Dawn"Demo?

�?????Perlin?????Implementing Improved Perlin Noise?

�??Vulcan Demo???????Fire in the"Vulcan"Demo?

�?????????Simulating Diffraction?

�????????????Efficient Shadow Volume Rendering?

�?????????Cinematic Lighting?

�???????????Shadow Map Antialiasing?

�???????????Omnidirectional Shadow Mapping?

�???????????????????Generating Soft Shadows Using Occlusion Interval Maps?

�??????????Perspective Shadow Maps:Care and Feeding?

�???????????????Managing Visibility for Per-Pixel Lighting?

�?????BRDF?Spatial BRDFs?

�???????????Image-Based Lighting?

�?????????Texture Bombing?

�?????????Color Controls?

�???????Depth of Field?

�?????????????High-Quality Filtering?

�?????????????????????Fast Filter-Width Estimates with Texture Maps?

�????OpenEXR???????HDR?The OpenEXR Image File Format and HDR?

PS:????????????????1?5?????????�????�?????????�????????????????????????????????????????????????????????????????????GitHub???

QianMo/Game-Programmer-Study-Notesgithub.com

?GPU Gems 1?????????

??????????GPU Gems 1????????????????????

PS:?????????????????????????????exe?????????????????

�?????Web???

GPU Gemsdeveloper.nvidia.com

�?????????�GPU-Gems-CD-Content�?GitHub?????????GPU Gems?1~3??????????????????????????????????????????

QianMo/GPU-Gems-Book-Source-Codegithub.com

????�?????????

?????????????Real-Time Approximations to Subsurface Scattering?

??????

??????Subsurface Scattering????SSS??3S?????????????????????????????????????????????????????????????????????????????

??????????

????????????

??????????????????????????????Subsurface Scattering???????????

???????????????????????????|??????????

?????????????4????????????????????????4??????????????????

????????????? ?????4?

??????????????????????????????????????????????????

????????


4.1???????????The Visual Effects of Subsurface Scattering?

???????????????????????????????????????????????????????????????????????????Subsurface

Scattering???????

1????????????????????????

2???????????????????????????????????

3?????????????????????

4?????????????????????????????????????????????????????????????????????????????????????????????????????????????

??????????

4.2????????Simple Scattering Approximations?

?????????????????Warp Lighting??????????????????????????Lambert??????????0??????????????????????????????????????????????????????????????????????????????????Oren-Nayar?????????????????????????????????Nayar and Oren 1995??

??????????????????????????????????

???wrap?????????????0?1??????????????????????

??????????

1. float diffuse = max(0, dot(L, N));
   
2. 
   
3. float wrap_diffuse = max(0, (dot(L, N) + wrap) / (1 + wrap));
   

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??????????????????????????????????????????????????

???????0??????????????????????????????????????????????????????????????????

??????????alpha?????????????????power???????????Example 16-1??FX??????????????????????

??a???????????b???????????c???????????????

Example 16-1????????????Shader??????Excerpt from the Skin

Shader Effect Incorporating Wrap Lighting?

1. // ???????2D????Generate 2D lookup table for skin shading?
   
2. 
   
3. float4 GenerateSkinLUT(float2 P : POSITION) : COLOR
   
4. 
   
5. {
   
6. 
   
7.     float wrap = 0.2;
   
8. 
   
9.     float scatterWidth = 0.3;
   
10. 
    
11.     float4 scatterColor = float4(0.15, 0.0, 0.0, 1.0);
    
12. 
    
13.     float shininess = 40.0;
    
14. 
    
15.     float NdotL = P.x * 2 - 1; // remap from [0, 1] to [-1, 1]
    
16. 
    
17.     float NdotH = P.y * 2 - 1;
    
18. 
    
19.     float NdotL_wrap = (NdotL + wrap) / (1 + wrap); // wrap lighting
    
20. 
    
21.     float diffuse = max(NdotL_wrap, 0.0);
    
22. 
    
23.     // ????????????????add color tint at transition from light to
    
24.     dark?
    
25. 
    
26.     float scatter = smoothstep(0.0, scatterWidth, NdotL_wrap) *
    
27. 
    
28.     smoothstep(scatterWidth * 2.0, scatterWidth,
    
29. 
    
30.          NdotL_wrap);
    
31. 
    
32.     float specular = pow(NdotH, shininess);
    
33. 
    
34.     if (NdotL_wrap <= 0) specular = 0;
    
35. 
    
36.     float4 C;
    
37. 
    
38.     C.rgb = diffuse + scatter * scatterColor;
    
39. 
    
40.     C.a = specular;
    
41. 
    
42.     return C;
    
43. 
    
44. }
    
45. 
    
46. // ??????????Shade skin using lookup table?
    
47. 
    
48. half3 ShadeSkin(sampler2D skinLUT,
    
49. 
    
50.     half3 N,
    
51. 
    
52.     half3 L,
    
53. 
    
54.     half3 H,
    
55. 
    
56.     half3 diffuseColor,
    
57. 
    
58.     half3 specularColor) : COLOR
    
59. 
    
60. {
    
61. 
    
62.     half2 s;
    
63. 
    
64.     s.x = dot(N, L);
    
65. 
    
66.     s.y = dot(N, H);
    
67. 
    
68.     half4 light = tex2D(skinLUT, s * 0.5 + 0.5);
    
69. 
    
70.     return diffuseColor * light.rgb + specularColor * light.a;
    
71. 
    
72. }

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4.3???????????Simulating Absorption Using Depth Maps?

???Absorption?????????????????????????????????????????????????????????????????????????????????????Depth Maps???[Hery 2002]?????????????(Shadow Mapping)???????????

????????????????????

?????Depth Maps????????

???????first pass?????????????????????????????????????????????standard projective texture mapping??????????????????rendering pass??????????????????????????????????????di????????????????????????do??????????????????????????????????S??????

????????????????????????Shader????????????????????????????

??????????????????????????

?????????????????????????????

????????????Single Scattering Approximation???????????????????????????????????????????????????????????????????????????????????????????????

?????????????Diffusion Approximation?????????????????????????

4.4?????????Texture-Space Diffusion?

???????????????????????????3D????????????????????Photoshop???Gaussian????????????????????????�??�??????????

????????????[Borshukov and Lewis 2003]??????????Texture-Space Diffusion???????????????????????????????UV????????????????[0?1]???????????[-1?1]????????

?????????????????????????????????????????

??a??????b???????????????????????

???????????????

???????????????????????????Shader????????????????????????????

??????????????????????????

?????????????

????????????? ?????4?

????????????? ?????4?

????????

????????????????????????????

1????????Warp Lighting?????????Oren-Nayar?????

2???????????????????????��???Absorption??

3???????????????Texture-Space Diffusion????????????????????��????????

????????????

Example 16-1????????????Shader??????Excerpt from the Skin

Shader Effect Incorporating Wrap Lighting?

Example 16-2??Pass???Shader???The Vertex Program for the Depth Pass?

Example 16-3??Pass???Shader???The Fragment Program for the Depth

Pass?

Example 16-4????????????????Shader???The Fragment Program

Function for Calculating Penetration Depth Using Depth Map?

Example 16-5?????????????????Shader???A Vertex Program to

Unwrap a Model and Perform Diffuse Lighting?

Example 16-6??????????Shader???The Vertex Program for Diffusion

Blur?

Example 16-7??????????Shader???The Fragment Program for Diffusion

Blur?

???????

?????Skin Rendering?

??????Subsurface Scattering?

????????Texture-Space Diffusion?

?????Warp Lighting?

?????Depth Maps?

????????Ambient Occlusion?

??????

?????????????????????????

??????Ambient Occlusion????AO??????????????????????????????????

??????????????????????????????????????????????????????????

???????????1???????????

????????

5.1??

???????????????Ambient Occlusion???????????

1?????????�??�??????????????????????????????

2?????????????????????????????????

??????????????

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

5.2??????The Preprocessing Step?

??????????????????????????????????

?1????�?????accessibility?�-???????????????????????;

?2???????????????

????????????????????????P?????N?P?????2/3?????????????????1/3??????????????B???????N??????????P??????????????????B????????????????????

?????????????

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

Example 17-1?????????????????Basic Algorithm for Computing Ambient Occlusion Quantities?

1. For each triangle {
   
2. 
   
3.     Compute center of triangle
   
4. 
   
5.     Generate set of rays over the hemisphere there
   
6. 
   
7.     Vector avgUnoccluded = Vector(0, 0, 0);
   
8. 
   
9.     int numUnoccluded = 0;
   
10. 
    
11.     For each ray {
    
12. 
    
13.         If (ray doesn't intersect anything) {
    
14. 
    
15.             avgUnoccluded += ray.direction;
    
16. 
    
17.             ++numUnoccluded;
    
18. 
    
19.         }
    
20. 
    
21.     }
    
22. 
    
23.     avgUnoccluded = normalize(avgUnoccluded);
    
24. 
    
25.     accessibility = numUnoccluded / numRays;
    
26. 
    
27. }

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????????????????????rejection sampling?????x?y?z?-1?1???3D???????????????????????????????

??????????????????????????17-2?????????????????

????????????????Monte Carlo??????????????????

Example 17-2????????????????????Algorithm for Computing

Random Directions with Rejection Sampling?

1. while (true) {
   
2. 
   
3.     x = RandomFloat(-1, 1); // random float between -1 and 1
   
4. 
   
5.     y = RandomFloat(-1, 1);
   
6. 
   
7.     z = RandomFloat(-1, 1);
   
8. 
   
9.     if (x * x + y * y + z * z > 1) continue; // ignore ones outside unit
   
10. 
    
11.     // sphere
    
12. 
    
13.     if (dot(Vector(x, y, z), N) < 0) continue; // ignore "down" dirs
    
14. 
    
15.     return normalize(Vector(x, y, z)); // success!
    
16. 
    
17. }
    

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??????????????????????????????

5.3??????????????Rendering with Ambient Occlusion Maps?

????????????????????

????????????????????????????????????????

?????????????

?1??????????????????????????????

?2???????????????

????????????????????????????????????????B????????????????????????????????????????????????????

??????????????????????????????????????????????????????????????????????????

????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

?????????????????????

????????????????????

???????????????????????????????????????????????????????????????????????????

????????

??????????????????????????????????

1?????????accessibility??

2???????????????

???????????????????????

�???????????????????

�?????????????????????????????????????????????

�???????????????????????????????

????????????

Example 17-1?????????????????Basic Algorithm for Computing

Ambient Occlusion Quantities?

Example 17-2????????????????????Algorithm for Computing

Random Directions with Rejection Sampling?

Example 17-3??????????????????Shader?Fragment Shader for

Shading with Accessibility Values and an Environment Map?

Example 17-4 latlong()??????The latlong()Function Definition?

Example 17-5 computeBlur()??????The computeBlur()Function Definition?

???????

??????Ambient Occlusion?

?????Rejection Sampling?

????????Ambient Occlusion Maps?

??????
?????https://zhuanlan.zhihu.com/p/36499291