Evolution of GPUs Chris Seitz PDF created with pdfFactory Pro trial version www.pdffactory.com Overview Concepts: Real-time rendering Hardware graphics pipeline Evolution of the PC hardware graphics pipeline: 1995-1998: Texture mapping and z-buffer 1998: Multitexturing 1999-2000: Transform and lighting 2001: Programmable vertex shader 2002-2003: Programmable pixel shader 2004: Shader model 3.0 and 64-bit color support ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Real-Time Rendering Graphics hardware enables real-time rendering Real-time means display rate at more than 10 images per second 3D Scene = Image = Collection of Array of pixels 3D primitives (triangles, lines, points) ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com PC Architecture Motherboard CPU System Memory Bus Port (PCI, AGP, PCIe) Graphics Board Video Memory GPU ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Hardware Graphics Pipeline Application 3D Geometry 2D Rasterization Pixels Stage Triangles Stage Triangles Stage For each For each triangle vertex: triangle: Transform Rasterize position: triangle 3D -> screen Interpolate Compute vertex attributes attributes Shade pixels Resolve visibility ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Real-time Graphics 1997: RIVA 128 –3M Transistors ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Real-time Graphics 2004: ©2004 NVIDIA Corporation. All rights reserved. UnRealEngine 3.0 Images Courtesy of Epic Games PDF created with pdfFactory Pro trial version www.pdffactory.com ‘95-‘98: Texture Mapping & Z-Buffer CPU GPU Application / Rasterization Stage Geometry Stage Raster Texture Rasterizer Operations Unit Unit 2D Triangles Bus (PCI) Frame 2D Triangles Textures Buffer Textures System Memory Video Memory ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Raster Operations Unit (ROP) Raster Texture Rasterizer Fragments Operations Unit Unit Scissor Test Fragment tested against scissor rectangle Screen Position Alpha Test (x, y) Frame Buffer tested against reference value Alpha Value Stencil Test Stencil Buffer a stencil buffer value at (x, y) tested against reference value Z-Buffer Depth Z Test z Color Buffer tested against z-buffer value at (x, y) Alpha Blending Color (Visibility test) Pixels (r, g, b) blended with color buffer value at (x, y) Ksrc * Colorsrc + Kdst * Colorsrc (src = fragment, dst = color buffer) ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Texture Mapping Triangle Mesh Base Texture (with UV coordinates) + = Sampling Magnification, Minification Filtering Bilinear, Trilinear, Anisotropic Mipmapping Perspective Correct Interpolation ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Texture Mapping: Mipmapping& Filtering or Bilinear Filtering TrilinearFiltering ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Filtering Examples Point Bilinear Trilinear Anisotropic (4X) & Trilinear ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Incoming ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Riva TNT –7M Transistors -1998 Multitexture ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com 1998: Multitexturing CPU GPU Application / Rasterization Stage Geometry Stage Multi Raster Rasterizer Texture Operations Unit Unit 2 2D Triangles Bus (AGP) Frame 2D Triangles Textures Buffer Textures System Memory Video Memory ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Multitexturing Base Texture modulated by Light Map X from UT2004 (c) Epic Games Inc. = Used with permission ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com GeForce 256 –23M Transistors -1999 Hardware Transform & Lighting ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com 1999-2000: Transform and Lighting CPU GPU “Fixed Function Pipeline” Application Geometry Stage Rasterization Stage Stage Transform Raster Register & Lighting Rasterizer Operations Texture Combiner Unit Unit Unit 3D Bus Triangles (AGP) Frame 3D Triangles Textures Buffer Textures System Memory Video Memory ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Transform and Lighting Unit (TnL) Transform and Lighting Unit Transform Lighting World Matrix Model or Object Space Material Properties World Space Light Properties Model-View Matrix View Matrix Vertex Color Camera or Eye Space Projection Matrix Projection or Clip Space Perspective Division & Viewport Matrix Vertex Diffuse & Screen or Window Space Specular Color ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Wanda and Bubble ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com GeForce 2 Pixel Shading Multitexture ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com GeForce 3 Programmable Vertex Shading ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com 2001: Programmable Vertex Shader CPU GPU Application Geometry Stage Rasterization Stage Stage Vertex Raster Rasterizer Register Shader Texture Operations (no flow w/ Z-Cull Combiner control) Unit Unit (4 Textures) 3D Bus Triangles (AGP) Frame 3D Triangles Textures Buffer Textures System Memory Video Memory ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Vertex Shader A programmable processor for any per-vertex computation void VertexShader( // Input per vertex in float4 positionInModelSpace, in float2 textureCoordinates, in float3 normal, // Input per batch of triangles uniform float4x4 modelToProjection, uniform float3 lightDirection, // Output per vertex out float4 positionInProjectionSpace, out float2 textureCoordinatesOutput, out float3 color ) { // Vertex transformation positionInProjectionSpace= mul(modelToProjection, positionInModelSpace); // Texture coordinates copy textureCoordinatesOutput= textureCoordinates; // Vertex color computation color = dot(lightDirection, normal); } ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Bump Mapping Bump mapping involves fetching the per-pixel normal from a normal map texture (instead of using the interpolated vertex normal) in order to compute lighting at a given pixel + = Diffuse light Normal Map Diffuse light with bumps ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Cubic Texture Mapping Cubemap z Environment Mapping Reflection vector (x, y,z) y is used to lookup x into the cubemap Cubemaplookup in direction (x, y, z) ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Projective Texture Mapping Projected Texture (x, y, z, w) Texture Projection (x/w, y/w) Projective Texture lookup ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Volume Texture Mapping z (x,y,z) y Volume Texture x Solid Textures 3D Noise Noise Perturbation Volume Texture lookup with position (x, y, z) ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Hardware Shadow Mapping Shadow Map Computation z/w The shadow map contains the depth (z/w) of the 3D points visible from (x, y, z, w) Spot the light’s point of view: (x/w, y/w) light Shadow Rendering shadow map A 3D point (x, y, z, w) is in shadow if: value z/w< value of shadow map at (x/w, y/w) (x, y, z, w) Spot (x/w, y/w) A hardware shadow map lookup light returns the value of this comparison between 0 and 1 ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Antialiasing: Examples ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com Antialiasing: Supersampling & Multisampling Supersampling: Compute color and Z at higher resolution and display averaged color to smooth out the visual artifacts Multisampling: Same thing except only Z is computed at higher resolution Multisampling performs antialiasing on primitive edges only ©2004 NVIDIA Corporation. All rights reserved. PDF created with pdfFactory Pro trial version www.pdffactory.com X-Isle: Dinosaur Isle ©2004 NVIDIA Corporation. All rights reserved. Image courtesy of Crytek PDF created with pdfFactory Pro trial version www.pdffactory.com