© Copyright Khronos Group, Page 1 Shaders Go Mobile: An Introduction to OpenGL ES 2.0 Tom Olson, Texas Instruments Inc.

TI Proprietary Information 2 About Texas Instruments A Strong Supporter of Standards  Khronos Promoting Member  Active in OpenGL ES, OpenMAX, OpenKODE The Leader in Semiconductors for Wireless  #1 in wireless revenue (Dataquest)  #1 in digital basebands (Forward Concepts 2006)  Over 2B handsets shipped  #1 in wireless application processors (FC 2006)  Over 90M OMAP processors shipped

© Copyright Khronos Group, Page 3 Outline Introduction to OpenGL ES What it is Design principles Versions and status OpenGL ES 2.0 What’s different about the API What’s different about the shading language Status …and where to go for more information

© Copyright Khronos Group, Page 4 What is OpenGL ES? The Leading 3D Graphics API for Mobile Devices Defined by the Khronos Group Created with blessing and cooperation of the OpenGL ARB Subset of Desktop OpenGL …with a few well-chosen mobile-specific extensions Design Goal Deliver most of the power of OpenGL …but in a much smaller package Design Principles Eliminate redundancy - one way to do things Eliminate rarely used, legacy, or expensive features Eliminate features not used in games

© Copyright Khronos Group, Page 5 Overview of OpenGL ES 1.x Features removed from desktop OpenGL Begin/End - vertex arrays & buffers only Fancy features: imaging subset, evaluators, display lists Legacy features: color index, DrawPixels Double precision data types & entry points Almost everything else is still there! Vertex Transforms & Lighting (mostly) Multi-texturing (2D only) fsAA via Multisampling Basic blending Features added Fixed-point and byte data Fixed-point only profile available

© Copyright Khronos Group, Page 6 OpenGL ES Versions OpenGL ES 1.1 Spec released at SIGGRAPH 2004 Adopted as standard in many mobile OSes Hardware accelerated ES 1.1 shipping in volume The ‘sweet spot’ for high-end mobile phone content today OpenGL ES 2.0 Final spec to be released in 4Q 2006 The ‘sweet spot’ in 200?

© Copyright Khronos Group, Page 7 Why OpenGL ES 2.0? Doom 3’s Zombies Far Cry’s Water Unreal’s Rocks Halo’s Ice Cause shaders are so cool…

© Copyright Khronos Group, Page 8 OpenGL ES 2.0 Key Changes Add: Vertex and Fragment Shaders ES Shader Language (GLSL ES) Option for off-line compilation (binary shaders) Remove Anything you can do in a shader Fixed function transform and lighting Fixed function texturing, fog, etc. That’s right is NOT backward compatible with 1.x! But, ES 2.0 HW can support an ES 1.x driver

© Copyright Khronos Group, Page 9 Fragment Processor Vertex Processor xform Light Vtx Coords Normals Colors TexCoords Primitive assembly Cull Clip Viewport Rasterize Z-test Stencil ScissorBlend VERTICESTRIANGLESFRAGMENTS APPLICATION State VectorState cmds Input Indices Attribute 0 … … Attribute n-1 tex0 tex1 fog What Changes From ES 1.1 to ES 2.0? General-purpose attributes replace fixed input arrays Vertex shader programs replace transform and lighting General-purpose uniforms replace fixed lighting & texture state General-purpose varyings replace fixed fragment attributes Fragment shader programs replace texture / fog / alpha test The OpenGL ES 2.0 Pipeline

© Copyright Khronos Group, Page 10 Other Features Added to ES 2.0 Texture Features Cube Maps Minimum of eight texture units Frame Buffer Objects Simplified version of EXT_frame_buffer_object Mandated minimum configuration support Per-Fragment Ops Stencil buffer support is required BlendEquation and BlendEquationSeparate supported (mostly) Point Sprites Regular GL points removed

© Copyright Khronos Group, Page 11 Optional Features Optional ETC Texture Compression IP contributed by Ericsson NPOT Textures 3D Textures Visibility Queries Half Float Data Float / Half Float Textures

© Copyright Khronos Group, Page 12 The ES Shader Language GLSL ES is very similar to GLSL, but… No fixed function attributes glVertex, glMultiTexCoord, glColor… No fixed function Uniforms glModelViewMatrix, glLight[ i ], … Predefined varyings are still there Vertex shader must write glPosition Fragment shader can read glFragCoord Fragment shader must write glFragColor

© Copyright Khronos Group, Page 13 Precision Qualifiers GLSL ES Range of precisions Low - range [-2,2] with 8 bits precision Medium - range [-2 14,2 14 ] with 10 bits precision High - range [-2 62,2 62 ] with 16 bits precision Can declare per variable, or declare a default precision Examples lowp vec4 color; highp vec3 LightPosition; Defaults Vertex Shader variables default to high precision Fragment Shader has no default - MUST declare

© Copyright Khronos Group, Page 14 Other Changes to GLSL ES Invariance Optimization may affect value of expressions Handled in Desktop GLSL by ftransform() Handled in GLSL ES by invariant keyword No Virtualization Valid programs may fail to compile due to resource limits Conformance test will enforce reasonable capability Any OpenGL ES 1.1 state should compile

© Copyright Khronos Group, Page 15 Conclusion OpenGL ES 2.0 is coming Full vertex and fragment shader support for mobile devices Small, clean API thanks to elimination of fixed functionality For more information Draft specs at Final specification coming soon!