Introduction to Graphics Hardware and GPUs

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Introduction to Graphics Hardware and GPUs
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Overview

• Definition
• Motivation
• History of Graphics Hardware
• Graphics Pipeline
• Vertex and Fragment Shaders
• Modern Graphics Hardware
• Stream Programming
• GPU Stream Programming
• Languages
• Exercise
• More Information

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Definition
Logical Representation of Visual Information
Output Signal
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(No Transcript)
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Motivation

• Real Time 15 60 fps
• High Resolution

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Motivation

• High CPU load
• Physics, AI, sound, network,
• Graphics demand
• Fast memory access
• Many lookups vertices, normal, textures,
• High bandwidth usage
• A few GB/s needed in regular cases!
• Large number of flops
• Flops Floating Point Operations ADD, MUL,
  SUB,
• Illustration matrix-vector products
• (16 MUL 12 ADD) x (vertices normals) x fps
  
• (28 Flops) x (6.000.000) x 30 5GFlops
• Conclusion Real time graphics needs supporting
  hardware!

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History of Graphics Hardware

• - mid 90s
• SGI mainframes and workstations
• PC only 2D graphics hardware
• mid 90s
• Consumer 3D graphics hardware (PC)
• 3dfx, nVidia, Matrox, ATI,
• Triangle rasterization (only)
• Cheap pushed by game industry
• 1999
• PC-card with TnL Transform and Lighting
• nVIDIA GeForce Graphics Processing Unit (GPU)
• PC-card more powerful than specialized
  workstations
• Modern graphics hardware
• Graphics pipeline partly programmable
• Leaders ATI and nVidia
• ATI Radeon X1900 XTX and nVidia GeForce 7900
  GTX
• Game consoles similar to GPUs (Xbox)

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Graphics Pipeline
LOD selection Frustum Culling Portal
Culling
Application
Modelview/Projection tr. Clipping
Lighting Division by w Primitive
Assembly Viewport transform Backface culling
Geometry Processing
Scan Conversion Fragment Shading Color and
Texture interpol. Frame Buffer Ops Z-buffer,
Alpha Blending,
Rasterization
Output to Device
Output
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Graphics Pipeline
LOD selection Frustum Culling Portal
Culling
Application
Programmable
Clipping Division by w Primitive
Assembly Viewport transform Backface culling
VERTEX SHADER
Geometry Processing
Scan Conversion
Rasterization
FRAGMENT SHADER
Output to Device
Output
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Vertex and Fragment Shaders
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Modern Graphics Hardware

• GPU Graphics Processing Unit
• Vector processor
• Operates on 4 tuples
• Position ( x, y, z, w )
• Color ( red, green, blue, alpha )
• Texture Coordinates ( s, t, r, q )
• 4 tuple ops, 1 clock cycle
• SIMD Single Instruction Multiple Data
• ADD, MUL, SUB, DIV, MADD,

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Modern Graphics Hardware

• Pipelining
• Number of stages
• Parallelism
• Number of parallel processes
• Parallelism pipelining
• Number of parallel pipelines

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Modern Graphics Hardware

• Parallelism pipelining ATI Radeon 9700

4 vertex pipelines
8 pixel pipelines
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Modern Graphics Hardware

• Features of ATI Radeon X1900 XTX
• Core speed 650 Mhz
• 48 pixel shader processors
• 8 vertex shader processors
• 51 GB/s memory bandwidth
• 512 MB memory

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Modern Graphics Hardware

• High Memory Bandwidth

Graphics Card
High bandwidth 51GB/s
GPU 650Mhz
Graphics memory ½GB
Output
AGP bus 2GB/s
Parallel Processes
Processor Chip
Main memory 1GB
AGP memory ½GB
High bandwidth 77GB/s
CPU 3Ghz
3GB/s
Cache ½MB
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Stream Programming

• Input stream of data records
• Output stream(s) of data records
• Kernel operates sequentially on the data
  records, accessing one record at a time!
• Read-Only Memory record independent read only
  memory

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GPU Stream Programming

• Vertex Shader
• Input and output streams
• Vertices, normals, colors, texture coordinates
• Read only memory
• Uniform variables
• Uniform constant per stream
• Textures, floats, ints, arrays,
• Fragment Shader
• Input and output streams
• Pixels
• Z-values
• Read only memory
• See above

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Languages

• Assembly
• Cg C for Graphics
• HLSL High Level Shading Language
• GLSL OpenGL Shading Language
• Sh
• BrookGPU

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Assembly

• Specialized Instruction Set
• DP4 4 tuple dot poduct
• RSQ reciprocal square root
• MAD multiply and add
• DPH homogeneous dot product
• SCS sine and cosine
• LRP linear interpolate
• TEX texture map
• Nowadays, not used directly anymore
• Generated by high level language compilers

• !!ARBvp1.0
• ATTRIB pos vertex.position
• PARAM mat4 state.matrix.mvp
• Transform by concatenation of the
• MODELVIEW and PROJECTION
• matrices.
• DP4 result.position.x, mat0, pos
• DP4 result.position.y, mat1, pos
• DP4 result.position.z, mat2, pos
• DP4 result.position.w, mat3, pos
• Pass the primary color through w/o
• lighting.
• MOV result.color, vertex.color
• END

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Cg / HLSL / GLSL

• High level programming language
• Static conditional jumps
• if, while, for,
• Data dependent conditional jumps
• SIMD Fragment shader only efficient in case of
  coherent program flow!
• No pointers!

• struct appdata
• float4 position POSITION
• float3 normal NORMAL
• float3 color DIFFUSE
• float3 VertexColor SPECULAR
• struct vfconn
• float4 HPOS POSITION
• float4 COL0 COLOR0
• vfconn main(
• appdata IN,
• uniform float4 Kd,
• uniform float4x4 mvp )
• vfconn OUT
• OUT.HPOS mul( mvp, IN.position)
• OUT.COL0.xyz Kd.xyz IN.VertexColor.xyz
• OUT.COL0.w 1.0
• return OUT

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Sh

• Shader code embedded in C

• // C Code
• vsh SH_BEGIN_VERTEX_PROGRAM
• ShInputNormal3f normal
• ShInputPosition4f p
• ShOutputPoint4f ov
• ShOutputNormal3f on
• ShOutputVector3f lvv
• ShOutputPosition4f opd
• opd Globalsmvp p
• on normalize( Globalsmv normal )
• ov -normalize( Globalsmv p )
• lvv normalize( GlobalslightPos
• ( Globalsmv p) ( 0,1,2 ) )
• SH_END_PROGRAM
• fsh SH_BEGIN_FRAGMENT_PROGRAM
• ShInputVector4f v
• ShInputNormal3f n
• ShInputVector3f lvv

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BrookGPU

• GPGPU Language
• General Purpose GPU Language
• Brook Streaming extension of C
• BrookGPU GPU port of Brook
• No computer graphics knowledge required!

• kernel void k( float sltgt, float3 f, float
  a1010, out float oltgt )
• float alt100gt
• float blt100gt
• float clt10,10gt
• streamRead( a, data1 )
• streamRead( b, data2 )
• streamRead( c, data3 )
• // Call kernel "k"
• k( a, 3.2f, c, b )
• streamWrite( b, result )

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Screenshots

• nVidia Toolkit Reflection-Bump Mapping

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Screenshots

• Far Cry UBISOFT

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Screenshots

• NPR ATI Research Group

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Exercise

• Vertex Shader in Cg
• Free Form Deformation
• Framework available on website

Vertex Shader
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More Information

• nVidia
• http//developer.nvidia.com/
• ATI
• http//www.ati.com/developer/
• General Purpose GPU Programming
• http//www.gpgpu.org
• GPU Programming and Architecture
• http//www.cis.upenn.edu/suvenkat/700/
• Hardware
• http//www.beyond3d.com
• http//www.tomshardware.com

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Questions?