Dave Shreiner, ARM March 2009

Transcription

1 4 th Annual Dave Shreiner, ARM March 2009 Copyright Khronos Group, Page 1

2 Motivation - What s OpenGL ES, and what can it do for me? Overview - Lingo decoder - Overview of the OpenGL ES Pipeline - What s this Shader thing, and what s one look like? Where can you learn more - Specifications, books, man pages and more! The two-for-one deal - OpenGL ES and OpenCL goes together like peas and carrots Copyright Khronos Group, Page 2

3 The leading 3D rendering API for mobile devices - Based on desktop OpenGL but optimized for mobile / handheld devices - Removes redundancy & rarely used features - adds mobile-friendly data types - The power of OpenGL distilled into a much smaller package A smashing success! - Widely used in mobile phone handsets from every major handset manufacturer - Personal Navigation, Personal Media Player, Automotive, Set-Top Box, Mobile Internet Device - Brew, Windows Mobile, Symbian, Android, iphone OS, Limo, Embedded Linux OpenGL ES 1.1 has become the most widely deployed 3D API - Used in diverse applications, devices and markets Copyright Khronos Group, Page 3

4 OpenGL is too big for systems with limited resources - Floating point arithmetic - Features for CAD, medical imaging, et cetera - Legacy features that are no longer useful / recommended What to do? - Remove redundant, unused, or expensive functionality - Add features needed for embedded systems Result: OpenGL ES - A compact API that can do almost everything that full OpenGL can - while leveraging OpenGL tools and experience Copyright Khronos Group, Page 4

5 Mobile Games - US $2.4B in 2006, growing to - US $7.2B in 2010 (Informa) Composition-based User Interfaces - Mac OS X, Windows Vista - Coming soon in Symbian Other Uses - Implementing Flash / OpenVG - Application UIs - Navigation applications - Etc Copyright Khronos Group, Page 5

6 State Variables 3D Vertices and Attributes Geometry Processor Rasterization Fragment Processor Frame Buffer Update Models Screen Triangles Fragments Colored Fragments Image OpenGL ES Versions - OpenGL ES 1.x: fixed-function processors, programmed by register setting - OpenGL ES 2.x: programmable processors, programmed in Shader Languages Copyright Khronos Group, Page 6

7 Key Features - Based on OpenGL Vertex Arrays / Buffer Objects - Transform & Lighting - Multitexturing (min 2 units) - Fixed-point & Floating-point profiles Features Removed - Begin / End (immediate-mode interface) - Color Index Mode Copyright Khronos Group, Page 7

8 Fixed Function 3D Acceleration Key Features Fixed-point and Floating-point Data Formats Vertex Arrays and Buffer Objects Fixed-Function Transformation and Lighting Point, Line, Triangle, Triangle Strip, Triangle Fan Primitives Minimum 2 layer Multi-Texturing Vertex Skinning Functionality Texture Filtering Texture Compression Alpha Blending Z-Buffer / Stencil Buffer / Color Buffer Copyright Khronos Group, Page 8

9 Key Features - Adds vertex and fragment shader programming Removes fixed function pipeline Super-compact, efficient API High level language (GLSL ES) On-line or off-line compilation Advanced Feature Set - Eight attribs / varyings / textures - Cube Maps - Framebuffer Objects Copyright Khronos Group, Page 9

10 Programmable 3D Acceleration Key Features Programmable Transform and Lighting through Vertex Shader Programmable Pixel Rasterization through Fragment Shader Support for 3 levels of precision in the Shader Programs No Fixed Function Vertex or Fragment Shading - Breaks backwards compatibility! Fixed function components - Alpha Blending - Depth / Stencil Test - Texture Filtering Texture Compression - Including royalty free ETC Frame Buffer Objects - Exchange data within the pipeline without copies Copyright Khronos Group, Page 10

11 A (usually small) program written in a shading language - OpenGL ES 2.0 has its own shading language the OpenGL ES Shading Language Example Fragment Shader varying vec2 tc; // texture coords varying vec3 n; // lighting normal uniform vec3 lightpos; uniform sampler2d tex[2]; void main() { vec4 color = texture2d( tex[0], tc ); vec4 clouds = texture2d( tex[1], tc ); float dp = dot( n, lightpos ); vec4 brightness = max( 0.0, dp ); } gl_fragcolor = brightness * (color + clouds); Copyright Khronos Group, Page 11

12 Copyright Khronos Group, Page 12

13 The Khronos Web Site - Specifications, examples, and OpenGL ES 2.0 manual pages - OpenGL ES 1.1 pages coming soon Copyright Khronos Group, Page 13

14 OpenCL with OpenGL (ES) work together Both standards under one IP framework - Enables very close collaborative design Efficient, inter-api communication - While still allowing both APIs to handle the types of workloads for which they were designed OpenCL can efficiently share resources with OpenGL (ES) - Textures, Buffer Objects and Renderbuffers - Data is shared, not copied Applications can select compute device(s) to run OpenGL and OpenCL - Efficient queuing of OpenCL and OpenGL commands into the hardware - Flexible scheduling and synchronization Examples - Vertex and image data generated with OpenCL and then rendered with OpenGL - Images rendered with OpenGL and post-processed with OpenCL kernels - etc. etc. Copyright Khronos Group, Page 14

15 OpenGL ES versions - OpenGL ES 1.1 the fixed-function implementation - OpenGL ES 2.0 shader-based graphics All trademarked implementations rigorously tested - Working group agreed conformance tests OpenGL ES 2.0 final specification March 2007 OpenGL ES 2.0 provisional specification August 2005 OpenGL ES 2.0 Conformance Tests May 2008 OpenGL ES 2.0 accelerated products begin to ship High-end devices will ship with drivers for both OpenGL ES 1.1 and 2.0 OpenGL ES 1.1 with hardware acceleration is the Sweet Spot for Mobile 3D through 2008 OpenGL ES 1.1 will continue to be used in lower-cost devices Copyright Khronos Group, Page 15