1. Introduction to the Direct3D 11 Graphics Pipeline
Allison Klein
Senior Lead Program Manager
Direct3D Microsoft

2. Executive Summary: D3D 11
Direct3D 11 focuses on scalability and performance, a creating a better development experience, and extending the reach of the GPU
Direct3D 11 is a strict superset of D3D 10 & 10.1
D3D 11 adds support for new features to D3D 10.1
The fastest way to move to Direct3D 11 is to start developing on Direct3D 10/10.1 today
Direct3D 11 will be available on Windows Vista & future Windows operating systems
Direct3D 11 will run on down-level hardware
You can all go back to sleep now.

3. Outline
Overview
Drilldown
Summary

4. Direct3D 10 Cleaner API  Easier coding than Direct3D 9
More efficient DDI  Driver Optimization
A more consistent experience across hardware!
Tighter specification
Elimination of caps

5. Direct3D 10.1 Improved multisampling Improved fixed-function blending
MSAA depth access in shader
Expose sample positions
Explicit coverage control
4-sample MSAA required
Improved fixed-function blending
Per-MRT blend mode
16-bit integer blending
Arrays of cube maps

6. Direct3D 10.1 (Cont’d) Improved performance over Direct3D 10
6-10% for common cases
20-30% for applications relying on MSAA such as deferred shading engines
Algorithms closer to Direct3D 11 and future APIs

7. Direct3D Issues/Opportunities
Scalability
Performance
Cross-Platform Content and Techniques
General-Purpose Data-Parallel Computing

8. Outline
Overview
Drilldown
Summary

9. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

10. Current Authoring Pipeline
(Rocket Frog Taken From Loop &Schaefer, "Approximating Catmull-Clark Subdivision Surfaces with Bicubic Patches“)
Sub-D Modeling
Animation
Displacement Map
Polygon Mesh
Generate LODs

11. Character Authoring (Cont’d)
Trends
Denser meshes, more detailed characters
~5K triangles -> K triangles
More complex animations
Animations on polygon mesh vertices more costly
Result
Indirection in authoring pipeline more painful
Painful I/O issues
Solution
Use higher-level surface representation longer
Animate control cage (~5K vertices)
Generate displacement & normal maps

12. Direct3D 10 pipeline Plus Three new stages for Tessellation
Input Assembler
Direct3D 10 pipeline Plus Three new stages for Tessellation
Vertex Shader
Hull Shader
Tessellator
Domain Shader
Stream Output
Geometry Shader
Rasterizer
Pixel Shader
Output Merger

13. Hull Shader (HS) One Hull Shader invocation per patch HS input:
patch control pts
One Hull Shader invocation per patch
Hull Shader
HS output:
Patch control pts after
Basis conversion
HS output:
TessFactors (how much to tessellate)
fixed tessellator mode declarations
Tessellator
Domain Shader

14. Fixed-Function Tessellator (TS)
Hull Shader
Note: Tessellator does not see control points
TS input:
TessFactors (how much to tessellate)
fixed tessellator mode declarations
Tessellator
TS output:
U V {W} domain points
TS output:
topology
(to primitive assembly)
Domain Shader
Tessellator operates per patch

15. Domain Shader (DS)
Hull Shader
Tessellator
DS input:
control points
TessFactors
DS input:
U V {W} domain points
Domain Shader
One Domain Shader invocation per point from Tessellator
DS output:
one vertex

16. Direct3D 11 Pipeline D3D11 HW Feature D3D11 Only
Input Assembler
Vertex Shader
D3D11 HW Feature
D3D11 Only
Fundamental primitive is patch (not triangle)
Superset of Xbox 360 tessellation
Hull Shader
Tessellator
Domain Shader
Stream Output
Geometry Shader
Rasterizer
Pixel Shader
Output Merger

17. Example Surface Processing Pipeline
Single-pass process!
vertex shader
hull shader
tessellator
domain shader
Animate/skin
Control
Points
Transform basis,
Determine how
much to tessellate
Tess
Factors
Tessellate!
Evaluate
surface
including
displacement
patch
control points
transformed
control points
control points
in Bezier patch
U V {W}
domain points
Sub-D Patch
Bezier Patch
displacement
map

18. New Authoring Pipeline
(Rocket Frog Taken From Loop &Schaefer, "Approximating Catmull-Clark Subdivision Surfaces with Bicubic Patches“)
Sub-D Modeling
Animation
Displacement Map
Optimally Tessellated Mesh
GPU

19. Tessellation: Summary
Helps us get closer to eliminating “pointy heads”
Scales visual quality across PC hardware configurations
Supports performance increases
Coarse model = compression, faster I/0 to GPU
Rendering tailored to each end user’s hardware
Better cross-platform (Windows + Xbox 360) development experience
Xbox 360 has a subset of D3D11’s tessellation
Parity = ease of cross-platform development
Extra features = innovation for Windows gaming
Render content as the artist created it!

20. Want to Know More? “Direct3D 11 Tessellation”
Tuesday, 4:00-4:55pm (Next) Kev Gee (Microsoft)
“Advanced Topics in GPU Tessellation”
Wednesday, 10:15-11:10am Natasha Tatarchuk (AMD)
“Water-Tight, Textured, Displaced Subdivision Surface Tessellation Using Direct3D 11”
Wednesday, 1:30-2:25pm Ignacio Castano (NVIDIA)

21. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

22. GPGPU = Data Parallel Computing
4/6/2017 5:47 AM
GPGPU = Data Parallel Computing
GPU performance continues to grow
Many applications scale well to massive parallelism without tricky code changes
Direct3D is the API for talking to GPU
How do we expand Direct3D to GPGPU?

23. Direct3D 11 Pipeline
Input Assembler
Direct3D 10 pipeline Plus Three new stages for Tessellation Compute Shader
Vertex Shader
Hull Shader
Tessellator
Domain Shader
Stream Output
Geometry Shader
Rasterizer
Data Structure
Compute Shader
Pixel Shader
Output Merger

24. Integration with Direct3D
Fully supports all Direct3D resources
Targets graphics/media data types
Evolution of DirectX HLSL
Graphics pipeline updated to emit general data structures…
…which can then be manipulated by compute shader…
And then rendered by Direct3D again

25. Example Scenario Render scene Write out scene image
Input Assembler
Render scene
Write out scene image
Use Compute for image post-processing
Output final image
Vertex Shader
Hull Shader
Tessellator
Domain Shader
Stream Output
Geometry Shader
Rasterizer
Data Structure
Compute Shader
Pixel Shader
Output Merger

26. Target Applications Image/Post processing: A-Buffer/OIT
Image Reduction
Image Histogram
Image Convolution
Image FFT
A-Buffer/OIT
Ray-tracing, radiosity, etc.
Physics AI

27. Compute Shader: Summary
Enables much more general algorithms
Transparent parallel processing model
Full cross-vendor support
Broadest possible installed base

28. Want to Know More?
“Direct3D 11 Compute Shader— More Generality for Advanced Techniques”
Wednesday, 4:00-4:55pm Chas Boyd (Microsoft)

29. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

30. Multithreading Today
Physics
Graphics AI
GPU

31. Multithreading Today
CPU-Bound Graphics
Physics AI
GPU

32. D3D11 Multithreading Usage
Enables distribution across threads of
Application code
Runtime
Driver
Device: free threaded resource creation
Immediate Context: your single primary device for state & draws
Deferred Contexts: your per-thread devices for state & draws
Display Lists: Recorded sequence of graphics commands

33. Direct3D 11 Multithreading
Now, the following can be distributed across threads:
Application
Direct3D 11 Runtime
Direct3D 11 Drivers
Updated Direct3D 10 and 10.1 Drivers

34. Direct3D 11 Multithreading
Application
Direct3D 11 Runtime
Existing 10/10.1 Drivers
Direct3D 11 Driver
Direct3D 10/10.1 HW
Direct3D 11 HW

35. Direct3D 11 Multithreading
Application
Direct3D 11 Runtime
New 10/10.1 Drivers
Direct3D 11 Driver
Direct3D 10/10.1 HW
Direct3D 11 HW

36. Multithreading: Summary
Improves performance
Scalable across hardware configurations in two ways:
# of CPUs
Graphics cards/drivers
Better cross-platform (Windows+Xbox 360) development experience

37. Want to Know More? “Multithreaded Rendering for Games”
Wednesday, 1:30-2:25pm
Matt Lee (Microsoft)

38. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

39. Shader Issues Today Shaders getting bigger, more complex
Shaders need to target wide range of hardware
Two approaches today:
Write specialized shaders
Good: Build optimal shaders as specializations
Bad: Generates lots of shaders
Write “one shader to rule them all”
Combines multiple shaders
Good: Reduces shader binding changes
Bad: Code is complex
Answer: Subroutines

40. Shader Subroutines Über-shader Dynamic Subroutine
foo (…) { if (m == 1) { // do material 1 } else if (m == 2) { // do material 2 } if (l == 1) { // do light model 1 } else if (l == 2) { // do light model 2
Material1(…) { … } Material2(…) { … } Light1(…) { … } Light2(…) { … } foo(…) { (*material)(…); (*light)(…); } Application binds appropriate *material, *light

41. Shader Subroutines Details Advantages Calls must be fast
Binding applies to all primitives in a Draw call
Binding operation must be fast
Need parameter passing mechanism
Need access to textures, samplers, etc.
Advantages
Reduce register usage in Über-shaders
Not worst case of all if statements
Allows specialization of subroutines

42. Want to Know More?
“High Level Shader Language (HLSL) Update—Introducing Version 5.0”
Tuesday, 5:05-6:00pm Michael Oneppo (Microsoft)

43. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

44. Why New Texture Formats?
Existing block palette interpolations too simple
Results often rife with blocking artifacts
No high dynamic range (HDR) support
NB: All are issues we heard from developers

45. Two New BC’s for Direct3D11
BC6 (aka BC6H)
High dynamic range
6:1 compression (16 bpc RGB)
Targeting high (not lossless) visual quality
BC7
LDR with alpha
3:1 compression for RGB or 4:1 for RGBA
High visual quality

46. New BC’s: Compression Block compression (unchanged)
Each block independent
Fixed compression ratio
Multiple block types (new)
Tailored to different types of content
Smooth gradients vs. noisy normal maps
Varied alpha vs. constant alpha
Also new: decompression results must be bit-accurate with spec

47. Multiple Block Types Different numbers of color interpolation lines
Less variance in one block means:
1 color line
Higher-precision endpoints
More variance in one block means:
2 (BC6 & 7) or 3 (BC7 only) color lines
Lower-precision endpoints and interpolation bits
Different numbers of index bits
2 or 3 bits to express position on color line
Alpha
Some blocks have implied 1.0 alpha
Others encode alpha

48. Partitions
When using multiple color lines, each pixel needs to be associated with a color line
Individual bits to choose is expensive
For a 4x4 block with 2 color lines
162 possible partition patterns
16 to 64 well-chosen partition patterns give a good approximation of the full set
BC6H: 32 partitions
BC7: 64 partitions, shares first 32 with BC6H

49. Example Partition Table
A 32-partition table for 2 color lines

50. Comparisons
Orig
BC3
BC7
Abs Error

51. Comparisons
Orig
BC3
BC7
Abs Error

52. Comparisons HDR Original at given exposure Abs Error BC6 at

53. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

54. A Plethora of Other Features
Addressable Stream Out
Draw Indirect
Pull-model attribute eval
Improved Gather4
Min-LOD texture clamps
16K texture limits
Required 8-bit subtexel, submip filtering precision
Conservative oDepth
2 GB Resources
Geometry shader instance programming model
Optional double support
Read-only depth or stencil views

55. Outline Overview Drilldown Summary Tessellation Compute Shader
Multithreading
Dynamic Shader Linkage
Improved Texture Compression
Quick Glance at Other Features
Summary

56. Direct3D 11 Direct3D 11 is strict superset of Direct3D 10 & 10.1
Direct3D 11 adds support for features like multithreading, tessellation, compute to Direct3D 10.1
The fastest way to move to Direct3D 11 is to start developing on Direct3D 10/10.1 today
Direct3D 11 will be available on Windows Vista and future Windows operating systems
Direct3D 11 will run on down-level hardware
Multithreading!
Direct3D 10.1, 10, and 9 hardware/drivers
Full functionality (for example, tessellation) will require Direct3D 11 hardware

57. When Can I Get It? Preview bits will be in November 2008 SDK
Will work on Windows Vista
Will run on Direct3D10/10.1 hardware
Full documentation, samples, etc.

58. Questions?

59. www.xnagamefest.com 4/6/2017 5:47 AM
© 2008 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only.
Microsoft makes no warranties, express or implied, in this summary.