1. Deferred Shading
Chun-Fu “Frank” Chao
Image from source 1

2. Outline
 Why(Why not) deferred shading
 History of deferred shading
 Basic of deferred shading
 Shadow in deferred shading
 Extension of deferred shading
◦ Light Pre-Pass deferred shading
◦ Anti-aliasing in deferred shading
◦ Inferred shading
◦ Tile-based deferred shading

3. What is deferred shading?
 Instead of intermediately calculate the
color and write to frame buffer, we divide
the information into smaller parts and
write them into intermediate buffer (i.e.
G(eometric)-buffer). Then combine and
calculate color later.
Video from source 15

4. Killzone 2 Behind the Bullet for
PlayStation 3
Video from source 2

5. Why deferred shading?
Image from source 26

6. Why deferred shading?
 Decouple the scene geometry complexity
and light complexity
◦ Going from O( #Light * #Triangle ) to
O( #Light ) + O( #Triangle )
 Only do the BRDF calculation on the
visible surfaces
 Simplify the rendering process
◦ Few passes on G-buffer V.S. Switching shaders
 G-buffer is useful for post-processing

7. Comparison with Forward
Rendering
 Single pass lighting:
For each object
Render object
Apply all the lights in shader
 Why this is not good?
◦ Boated shader if we do code generation for all
the light sources
◦ Wasteful ( We are throwing away fully shaded
fragment in depth test !)
From source 4, slide 3

8. Comparison with Forward
Rendering
 Multi-pass lighting:
For each light
For each object affected by light
Framebuffer += BRDF( object, light )
 Why this is not good?
◦ Repetitive vertex transformation for the same
object
◦ Wasteful ( We are “still” throwing away fully
shaded fragment in depth test !)
From source 4, slide 4

9. Deferred Shading
For each object
Render the lighting(material) property
into G-buffer
For each light
Framebuffer += BRDF( G-buffer, light )
 Simplify the lighting process
 O(1) depth complexity for lighting
From source 4, slide 5

10. Why “not” deferred shading?
 Memory intensive
◦ Multiple buffer ( Multiple render target )
◦ Buffer read-back
◦ Limited material type
 Cannot apply hardware assisted anti-aliasing
◦ MSAA(Multi-sample anti-aliasing) is for pixel
already shaded
 Cannot handle translucent object
◦ We only have the information of the object with
smallest depth value

11. History
 Deering, M., et al. “The Triangle
Processor and Normal Vector Shader:
A VLSI System for High Performance
Graphics”, Proceedings of SIGGRAPH
‘88
◦ Only shading once after depth resolution
 T. Saito and T. Takahashi.
“Comprehensible rendering of 3d
shapes”, Proceedings of SIGGRAPH ’90
◦ It is designed for contour rendering
◦ The first time the term of G-Buffer
appears
Image from source 6, 7

12. Multiple Render target
 A feature that allows programmable
rendering pipeline to render images to
multiple render target texture at the
same time.
 Introduced by OpenGL 2.0 and DirectX
9.0
 Supported by Xbox360 and Playstation 3

13. Multiple Render target
 We can do deferred shading without
Multiple render target.
◦ But the performance is going to be a problem
Image from source 6, 8

14. DEFERRED SHADING BASIC

15. What kind of G-buffer do we need?
 Going from the SSAO assignment we did

16. Say we want something like this
From source 9, slide 9

17. What kind of G-buffer do we need?
From source 9, slide 10

18. What kind of G-buffer do we need?
From source 9, slide 11

19. What kind of G-buffer do we need?
From source 9, slide 12

20. What kind of G-buffer do we need?
From source 9, slide 13

21. What kind of G-buffer do we need?
From source 9, slide 14

22. What kind of G-buffer do we need?
From source 9, slide 15

23. What kind of G-buffer do we need?
From source 9, slide 16

24. What kind of G-buffer do we need?
From source 9, slide 17

25. The G-Buffer of Killzone 2
 4 X R8G8B8 + 24Depth + 8Stencil ~= 36 MB
◦ We only got 256 MB RAM and 256 MB VRAM on
PS3 
 No Normal.z term
◦ Normal.z = sqrt( 1.0 – Normal.x^2 – Normal.y^2 )
◦ Trade memory space with computation time
From source 9, slide 19

26. The G-buffer of Battlefield 3
 Material ID is a common way to manage
material
R8 G8 B8 A8
GB0 Normal .xyz Spec. Smoothness
GB1 Diffuse albedo .rgb Specular albedo
GB2 Sky visibility Custom envmap ID Material Param. Material ID
GB3 Irradiance (dynamic radiosity)
Image from source 9, slide 12 and source 10

27. Lighting Result
Image from source 10, slide 31

28. SHADOW

29. That’s cool. But where is my shadow?
 1000 lights without shadow is easy, but
100 lights with shadow is impossible now

 Shadow map
◦ A good fit with deferred shading
◦ Need more memory 
 Shadow volume
◦ Render light as geometry volume
◦ Depth test to determine whether the object is
inside the volume or not

30. Shadow map
 Create a depth map in the perspective of light
source.
 Compare the position of the geometry
surface with the depth map of light source.
 Position = Screen space position + depth
Image from source 14

31. Ouch!
Image from source 16, Page 16

32. Shadow Volume
 Only apply the light to the pixel enclose by
the shadow volume
 Depth test needs to be handle carefully
Image from source 4, slide 12 Image from source 17

33. Xbox Gladiator 2k4 demo
Video from source 5

34. Wait! We still have plenty of
problems
 Memory usage
◦ Light Pre-Pass deferred shading
 Anti-aliasing
◦ MLAA ( Morphological Anti-aliasing )
◦ SRAA ( Sub-pixel Reconstruction Anti-Aliasing )
 Alpha blending
◦ Inferred shading

35. LIGHT PRE-PASS DEFERRED
SHADING

36. Light Pre-pass / Deferred Lighting
 Two pass deferred
shading
 1st pass
◦ Only render depth
and normal
◦ Do not need MRT!
Image from source 17

37. Light Pre-pass / Deferred Lighting
 Write LightColor * N dot L * Attenuation
in RGB, specular in A channel
Image from source 17

38. Light Pre-pass / Deferred Lighting
 2nd geometry pass
◦ Fetch the material property
◦ Combine with light buffer
Image from source 17

39. Light Pre-pass / Deferred Lighting
 Pro
◦ Less memory required
◦ Doesn’t not require MRT feature
= Enable programmer to turn on MSAA in
DirectX9
◦ Only one material fetch regardless number of
light
 Con
◦ “Two” geometry passes

40. ANTI-ALIASING

41. Anti-aliasing
 Super-sampling one framebuffer is painful,
super-sampling 5 MRT is 5X painful 
 Hardware supported MSAA is incompatible
with deferred shading
◦ MSAA cannot apply to MRT in DirectX 9
◦ Super-sampling and averaging normal or depth
might cause wired result
 Imaged based approach of anti-aliasing
 We have depth and normal information 

42. Basic Edge-detection Anti-aliasing
 Do the 2D edge detection algorithm on
frame buffer
 Apply low-pass filter across the edge
 The discontinuities of normal and depth
are better features to locate edges

43. Basic Edge-detection Anti-aliasing
 Detect depth or normal discontinuity is
better than the color discontinuity
Image from source 17

44. Morphological Anti-aliasing
 Detect the pattern of color discontinuity
 Draw triangular area based on the
pattern
Image from source 18

45. Morphological Anti-aliasing
 Connect the mid-points of the L, Z, and U
shape segments.
 The blending weight is based on the triangle
area enclosed by mid points
Image from source 18

46. Sub-pixel Reconstruction Anti-
Aliasing
 MLAA will alter the shape of the original
image
Image from source 20

47. Sub-pixel Reconstruction Anti-
Aliasing
 Determine the blending pattern based on
the super-sampled depth and normal
information
Image from source 20

48. Anti-aliasing comparison
Image from source 21, slide 44

49. Anti-aliasing comparison
Image from source 21, slide 45

50. Anti-aliasing comparison
Image from source 21, slide 46

51. Anti-aliasing comparison
Image from source 21, slide 47

52. Anti-aliasing comparison
Image from source 21, slide 48

53. Anti-aliasing comparison
Image from source 21, slide 49

54. INFERRED SHADING

55. Alpha blending
 How do we get transparent/transculant
effect in deferred shading
◦ One more forward rendering pass 
◦ Depth peeling
 So expensive 
 Limited layer of transculant material

56. Depth Peeling
 Multiple pass of depth buffer generation
from front to back
 Peel the fragments away after depth
buffer generated
 Render image form back to front
Image from source 22

57. Depth Peeling
Image from source 22

58. Inferred Shading
 3-pass algorithm based on the 2-pass
Light Pre-pass deferred shading
 Can create
transparent effect
in deferred shading
scheme
◦ Even multiple
layer of
transparency!
Image from source 23

59. Inferred Shading
 Geometry Pass
◦ RT1 : Normal.X / Normal.Y
◦ RT2 : Depth / Object ID
◦ The resolution is lower than target
 Light Pass
◦ Apply lighting to the G-buffer to create L-buffer
◦ The resolution is also lower that target
 Material Pass
◦ Material fetch
◦ Combine material with L-buffer information

60. Inferred Shading
 Discontinuity Sensitive Filtering
◦ Sample lighting information based on the
object ID information stored in G-buffer
◦ If the sample is not from the same object,
then ignore the sample
Image from source 23

61. Lighting Alpha Polygons
 Render the transparent objects last in the
geometry pass and render them into
stipple pattern
 Special sampling rule parse over the
stipple pattern in the material pass
Image from source 23

62. Stipple Pattern
Image from source 23

63. Material Pass : Render Opaque
Objects
Image from source 23

64. Material Pass : Render Transparent
Objects
Image from source 23

65. Multiple Layer of Transparency
Transparent
Opaque
1
Opaque Opaque
Transparent Transparent
1 3
Transparent
Opaque
2
Image from source 23

66. Resolution Decrease
Image from source 23

67. TILE-BASED DEFERRED
SHADING

68. Tile-based Deferred Shading
 Introduced into Frostbite 2 engine
 Divide the screen in screen-space tiles
 Cull analytical lights (point, cone, line), per
tile
 Compute lighting for all contributing lights,
per tile
Slide from source 25

69. Tile-based Deferred Shading
Image from source 10, slide 42

70. Tile-based Deferred Shading
Image from source 10, slide 43

71. Tile-based Deferred Shading
Image from source 10, slide 43

72. Tile-based Deferred Shading
• The screen is divided in 920 tiles of
32x32 pixels
• Downsample and classify the
scene from 720p to 40x23
(1 pixel == 1 tile)
• Find each tile’s Min/Max depth
• Find each tile’s material permutations
• Downsampling is done in multi-pass
and via MRTs
Slide from source 25

73. Tile-based Deferred Shading
Image from source 25, slide 72

74. Tile-based Deferred Shading
Image from source 25, slide 73

75. Tile-based Deferred Shading
Image from source 25, slide 74

76. Tile-based Deferred Shading
 Build mini-frustas for each tile
 Cull lights against sky-free tiles in a shader
 Store the culling results in a texture:
◦ Column == Light ID
◦ Row == Tile ID
 Actually, 4 lights can be processed at once
(A-R-G-B)
 Read back the contribution results on the
CPU and prepare for lighting!
Slide from source 25

77. Tile-based Deferred Shading
 Parse the culling results texture on CPU
 For each light type
For each tile
For each material permutation,
Regroup & set the light parameters for
the pixel shader constants
 Setup the shader loop counter
(Limited number of light passed)
 Additively render lights with a single draw
call (to the final HDR lighting buffer)
Slide from source 25

78. Tile-based Deferred Shading
Image from source 25, slide 66

79. Tile-based Deferred Shading
Image from source 25, slide 67

80. Tile-based Deferred Shading
Image from source 25, slide 68

81. Tile-based Deferred Shading
Image from source 25, slide 69

82. Thank you
 Questions?
Image from source 25

83. BONUS

84. GDC 2011
APPROXIMATING
TRANSLUCENCY

85. Demonstration
Image from source 1

86. Approximating Translucency
Image from source 1

87. Approximating Translucency
Image from source 1

88. SOURCE

89. Source
1. John Chapman, “Deferred Rendering, Transparency & Alpha Blending Tutorial”,
Available at:
http://john-chapman.net/content.php?id=13
2. Guerrilla Games, “Killzone 2 Behind the Bullet for PlayStation 3”, Available at:
http://www.youtube.com/watch?v=tzx_JfujYT4
3. Shawn Hargreaves, “Deferred Shading”, Available at:
http://www.shawnhargreaves.com/DeferredShading.pdf
4. Shawn Hargreaves, “Deferred Shading : 6800 Leagues Under The Sea”,
Available at:
http://http.download.nvidia.com/developer/presentations/2004/6800_Leagues/
6800_Leagues_Deferred_Shading.pdf
5. Rich Geldreich, “Deferred Lighting and Shading”, Available at:
https://sites.google.com/site/richgel99/
6. Deering, M., et al. “The Triangle Processor and Normal Vector Shader: A VLSI
System for High Performance Graphics”, Proceedings of SIGGRAPH ‘88 ,
Available at:
http://dl.acm.org/citation.cfm?id=378468

90. Source
7. T. Saito and T. Takahashi. “Comprehensible rendering of 3d shapes”, Proceedings
of SIGGRAPH ’90, Available at:
http://dl.acm.org/citation.cfm?id=97901
8. Filion, D. and McNaughton, R. (Blizzard Entertainment), “ StarCraft II: Effects &
Techniques”, slide available at:
http://developer.amd.com/gpu_assets/S2008-Filion-McNaughton-StarCraftII.pdf
Course note available at:
http://developer.amd.com/documentation/presentations/legacy/Chapter05-
Filion-StarCraftII.pdf
9. Michal Valient (Guerrilla), “Deferred Rendering in Killzone 2 “, Available at:
http://www.guerrilla-games.com/publications/dr_kz2_rsx_dev07.pdf
10. Christina Coffin (DICE), “SPU-based Deferred Shading for Battlefield 3 on
Playstation 3”, Available at:
http://publications.dice.se/publications.asp?show_category=yes&which_categor
y=Rendering
11. Colin Barré-Brisebois (DICE), “Approximating Translucency for a Fast, Cheap and
Convincing Subsurface Scattering Look”, Available at:
http://zigguratvertigo.com/tag/deferred-shading/

91. Source
12. Michal Valient (Guerrilla), “The Rendering Technology of Killzone 2”, Available at:
http://www.slideshare.net/guerrillagames/the-rendering-technology-of-killzone-
2
13. Michiel van der Leeuw (Guerrilla), “The PlayStation®3’s SPUs in the Real World: A
KILLZONE 2 Case Study “, Available at:
http://www.slideshare.net/guerrillagames/the-playstation3s-spus-in-the-real-
world-a-killzone-2-case-study-9886224
14. Wikipedia : Shadow Mapping
http://en.wikipedia.org/wiki/Shadow_mapping
15. Wikipedia : Deferred Shading
http://en.wikipedia.org/wiki/Deferred_shading
16. Johan Andersson (DICE), “5 Major Challenges in Interactive Rendering”,
Available at:
http://publications.dice.se/publications.asp?show_category=yes&which_categor
y=Rendering
17. Nicolas Thibieroz, “Deferred Shading Optimizations” ,
Available at:
http://developer.amd.com/gpu_assets/Deferred%20Shading%20Optimizations.p
ps

92. Source
18. Alexander Reshetov (Intel Labs ), “Morphological Antialiasing” , Available at:
http://visual-computing.intel-
research.net/publications/papers/2009/mlaa/mlaa.pdf
19. Alexandre De Pereyra (Intel), “MLAA: Efficiently Moving Antialiasing from the
GPU to the CPU”, Available at:
http://software.intel.com/en-us/articles/mlaa-efficiently-moving-antialiasing-
from-the-gpu-to-the-cpu/
20. Chajdas, McGuire, and Luebke, Subpixel Reconstruction Antialiasing, ACM
Symposium on Interactive 3D Graphics and Games (I3D 2011 proceedings),
February 2011, Available at:
http://graphics.cs.williams.edu/papers/SRAAI3D11/
21. Johan Andersson (DICE), “DirectX 11 Rendering in Battlefield 3”, Available at:
http://publications.dice.se/publications.asp?show_category=yes&which_categor
y=Rendering
22. Cass Everitt (Nvidia), “Interactive Order-Independent Transparency”, Available at:
http://developer.nvidia.com/content/interactive-order-independent-
transparency

93. Source
23. Scott Kircher and Alan Lawrance. 2009. Inferred lighting: fast dynamic lighting
and shadows for opaque and translucent objects. In Proceedings of the 2009
ACM SIGGRAPH Symposium on Video Games (Sandbox '09), Stephen N. Spencer
(Ed.). ACM, New York, NY, USA, 39-45. Available at:
http://dl.acm.org/citation.cfm?id=1581080
24. ENGEL, W., 2008. Diary of a graphics programmer: Light pre-pass renderer.
Online, accessed Jan. 27th, 2009. Available at:
http://diaryofagraphicsprogrammer.blogspot.com/2008/03/light-pre-pass-
renderer.html.
25. John White (Black Box), Colin Barré-Brisebois (DICE)“More Performance! Five
Rendering Ideas from Battlefield 3 and Need For Speed The Run”, Available at:
http://publications.dice.se/
26. Kenny Magnusson (DICE),“Lighting you up in Battlefield 3”
http://publications.dice.se/

94. Indirect Reference Source
1. Oles Shishkovtsov (GSC Game World), "GPU Gems 2 Chapter 9. Deferred Shading
in S.T.A.L.K.E.R.", Available at:
http://http.developer.nvidia.com/GPUGems2/gpugems2_chapter09.html
2. Rusty Koonce (NCsoft Corporation), "GPU Gems 3 chapter 19. Deferred Shading
in Tabula Rasa", Available at:
http://http.developer.nvidia.com/GPUGems3/gpugems3_ch19.html
3. Tiago Sousa(Crytek), "GPU Gems 3 chapter 16. Vegetation Procedural Animation
and Shading in Crysis", Available at:
http://http.developer.nvidia.com/GPUGems3/gpugems3_ch16.html
4. Wolfgang Engel, “ShaderX2 : introductions and tutorials with DirectX 9”,
Available at:
http://tog.acm.org/resources/shaderx/Introductions_and_Tutorials_with_Direct
X_9.pdf
5. Wolfgang Engel, “Light Pre-Pass -Deferred Lighting: Latest Development”,
Available at:
http://www.bungie.net/images/Inside/publications/siggraph/Engel/LightPrePass.
ppt

95. Indirect Reference Source
6. Mark Lee(Insomniac games), “Pre-lighting, Available at:
http://www.insomniacgames.com/tech/articles/0209/files/prelighting.pdf
7. Mark Lee(Insomniac games), “Pre-lighting in Resistance 2”, Available at:
http://www.insomniacgames.com/gdc09-resistance-2-prelighting/
8. Rouslan Dimitrov(Nvidia), “Cascaded Shadow Maps”, Available at:
http://developer.download.nvidia.com/SDK/10.5/opengl/src/cascaded_shadow_
maps/doc/cascaded_shadow_maps.pdf
9. Damian Trebilco, “Light Indexed Deferred Lighting”, Available at:
http://code.google.com/p/lightindexed-deferredrender/
10. Andrew Lauritzen(Intel), "Deferred Rendering for Current and Future Rendering
Pipelines", Available at:
http://visual-computing.intel-research.net/art/publications/deferred_rendering/
11. B. Segovia, J. C. Iehl, R. Mitanchey, and B. Péroche. 2006. Non-interleaved
deferred shading of interleaved sample patterns. In Proceedings of the 21st ACM
SIGGRAPH/EUROGRAPHICS symposium on Graphics hardware (GH '06). ACM,
New York, NY, USA, 53-60.
http://dl.acm.org/citation.cfm?id=1283909

96. Indirect Reference Source
12. John Tsiombikas, “Volume Shadows Tutorial”, Available at:
http://nuclear.mutantstargoat.com/
13. Stefan Brabec , Thomas Annen , Hans-peter Seidel, ” Shadow Mapping for
Hemispherical and Omnidirectional Light Sources”, Available at:
http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.11.3540
14. Emil Persson (AMD), “Depth In-depth “, Available at:
http://developer.amd.com/media/gpu_assets/Depth_in-depth.pdf
15. Sam Martin, Per Einarsson(Geomerics), “A Real Time Radiosity Architecture”
http://www.geomerics.com/downloads/radiosity_architecture.pdf
16. Martin Mittring(Crytek), “A bit more deferred – CryEngine3”, Available at:
http://www.crytek.com/cryengine/presentations&page=2
17. Anton Kaplanyan(Crytek), “CryENGINE 3: reaching the speed of light”
http://www.crytek.com/cryengine/presentations/CryENGINE3-reaching-the-
speed-of-light
18. Nickolay Kasyan, Nicolas Schulz, Tiago Sousa(Crytek), ”Secrets of CryENGINE 3
Graphics Technology”, Available at:
http://www.crytek.com/cryengine/presentations/secrets-of-cryengine-3-
graphics-technology

97. Indirect Reference Source
19. Martin Mittring(Epic games), Bryan Dudash(Nvidia), “The Technology Behind the
DirectX 11 Unreal Engine "Samaritan" Demo”, Available at:
http://www.nvidia.com/content/PDF/GDC2011/Epic.pdf
20. Dean Calver , “Photo-realistic Deferred Lighting”
http://www.beyond3d.com/content/articles/19/1
21. Anton Kaplanyan (Crytek) ,”Light Propagation Volumes in CryEngine 3” ,
Available at:
http://www.crytek.com/cryengine/cryengine3/presentations/light-propagation-
volumes-in-cryengine-3
22. Aths, “Multisampling Anti-Aliasing: A Closeup View “, Available at:
http://alt.3dcenter.org/artikel/multisampling_anti-aliasing/index3_e.php
23. Fabio Policarpo, Francisco Fonseca(CheckMate Games), “ Deferred Shading Tutorial”,
Available at:
http://www710.univ-
lyon1.fr/~jciehl/Public/educ/GAMA/2007/Deferred_Shading_Tutorial_SBGAMES2005.
pdf
24. Josh Klint (CEO, Leadwerks Corporation ), “Deferred Rendering in Leadwerks Engine “,
Available at:
http://leadwerks.com/files/Deferred_Rendering_in_Leadwerks_Engine.pdf

98. Previous Presentation
 [Spring 2011] Sean Thomas
http://smt565.blogspot.com/
 [Spring 2010] Ian Perera
http://www.seas.upenn.edu/~cis565/LEC
TURE2010/Deferred%20RenderingMacro.
pptm