December Copyright Khronos Group, Page 1

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1 December 2008 Copyright Khronos Group, Page 1

2 Announced at SIGGRAPH August Supported by AMD, Apple, Intel, NVIDIA, S3, Blizzard, TransGaming, and others State-of-the-art support for latest programmable 3D hardware - Estimated 100 million OpenGL 3.0-capable GPUs shipped - Provides rough feature parity with Direct3D 10 New deprecation model with profiles - Streamline and accelerate the development of the API Full interoperability with OpenCL - Close coordination with general compute acceleration Cross platform - Windows XP as well as Windows Vista, Linux, Mac OS, Specification at Strong collaboration among hardware and software vendors to solve real-world needs Copyright Khronos Group, Page 2

3 OpenGL is part of Khronos since July OpenGL s evolution was governed by the OpenGL Architectural Review Board (ARB) - Now officially a Khronos working group Well proven evolutionary process - OpenGL participants propose extensions - Successful extensions are polished and incorporated into core OpenGL 3.0 is great example of this process - Roughly 20 extensions folded into core - Just 3 of those previously unimplemented Copyright Khronos Group, Page 3

4 Programmability - Shader Model 4.0 features - OpenGL Shading Language (GLSL) 1.30 Texturing - New texture representations and formats Framebuffer operations - Framebuffer objects - New formats - New blit, clear, blend, and masking operations Buffer management - Non-blocking and fine-grain update of buffer object data stores Vertex processing - Vertex array configuration objects - Conditional rendering for occlusion culling - New half-precision vertex attribute formats Pixel processing - New half-precision external pixel formats All Brand New Core Features Copyright Khronos Group, Page 4

5 Vertex Array Objects - Encapsulate vertex array state for easier programming and increased throughput Non-blocking access to Vertex Buffer Objects - With the ability to update and flush a sub-range for enhanced performance Full framebuffer object functionality - Multi-sample buffers, blitting to and from framebuffer objects, rendering to one and two-channel data, and flexible mixing of buffer sizes and formats when rendering to a framebuffer object 32-bit floating-point textures and render buffers - Increased precision and dynamic range in visual and computational operations Conditional rendering - Based on occlusion queries for increased performance; Compact half-float vertex and pixel data - Saves memory and bandwidth Copyright Khronos Group, Page 5

6 Transform feedback to capture geometry data after vertex transformations - Buffer object can drive additional compute and rendering passes Four new texture compression schemes - One and two channel textures providing a factor of 2-to-1 storage savings over uncompressed data Rendering and blending into srgb framebuffers - Faithful color reproduction for OpenGL applications without adjusting the monitor's gamma correction Texture arrays - For efficient indexed access into a set of textures; 32-bit floating-point depth buffer support Copyright Khronos Group, Page 6

7 Front-to-back native signed and unsigned integer operations - Full integer-based texturing - Integer input and outputs for vertex and fragment shaders - True integer operators including bit-wise operations: ^, &,, <<. >>, %,~ Improved compatibility with OpenGL ES - Control over precision New interpolation modifiers - Centroid, no perspective, and flat New forms of explicit control over texturing operations - Base texture size queries, texel offsets to fetches - Explicit LOD and derivative control, texture arrays, integer samplers Additional built-in functions for manipulating floating-point numbers - Hyperbolic trig functions - trunc(), round(), roundeven(), isnan(), isinf(), modf() - Integer related: sign(), min/max(), abs(),. Switch statements - switch/case/default statements for enhanced flow control within shaders Copyright Khronos Group, Page 7

8 OpenGL 2.x extensions - to bring new functionality to older hardware OpenGL 3.0 extensions to test new functionality before bringing to core Copyright Khronos Group, Page 8

9 OpenGL has never removed features from the API - Commitment to backwards compatibility is one of OpenGL s strengths - After 15+ years, defining new features to work with old features becomes increasingly difficult OpenGL 3.0 does not remove any features - Everything still works OpenGL 3.0 marks certain features as deprecated: - Legacy and obsolete features - Parts of OpenGL unlikely to be accelerated - Redundant functionality Future OpenGL revisions may remove these deprecated features - Provides guidance to developers to prepare for future revisions - Plan to remove these features sooner, rather than later Copyright Khronos Group, Page 9

10 Incoming Extensions that may be integrated into Core in future DEPRECATED Functionality may be removed from future releases (and may have reduced interoperability with new functionality) Outgoing Extensions that may be dropped completely in future foo New Functionality Before Adoption into Core Core Specification Old Functionality Removed from Core time Copyright Khronos Group, Page 10

11 Profiles contain functionality needed to meet the needs of a particular market while minimizing costs. Conformant products may implement one or more Profiles Profile A New Functionality Before Adoption into Core Core Specification Old Functionality Removed from Core Profile B Core Specification The sum of all Profile functionality To avoid fragmentation, the core OpenGL specification will contain all defined functionality in an architecturally coherent whole, with profiles tightly specifying segmentrelevant subsets Copyright Khronos Group, Page 11

12 Profile A Profile A Forward Compatibility Context Developers may request a Forward Compatibility Context for a Profile - with non-deprecated functionality that is guaranteed to be present in next release New Functionality Before Adoption into Core Old Functionality Removed from Core Profile B Forward Compatibility Context Profile B Core Specification The sum of all Profile functionality Functionality not in the Forward Compatibility Context is DEPRECATED and may be removed from future releases (and may have reduced interoperability with new functionality) Copyright Khronos Group, Page 12

13 Fixed-function vertex and fragment processing Color-index mode Display lists, and Selection and Feedback modes GLSL 1.10 and 1.20 Begin/End based rendering Application-generated object names Quads and polygon primitives Polygon and Line Stipple Pixel transfer modes Bitmaps, DrawPixels, PixelZoom and quite a few others... - See Appendix E of OpenGL 3.0 specification for complete list Copyright Khronos Group, Page 13

14 Complementary capabilities - OpenGL 3.0 = state-of-the-art, cross-platform graphics - OpenCL 1.0 = state-of-the-art, cross-platform compute Efficient, inter-api communication - Both standards under one IP framework to enables very close collaborative design - While still allowing both APIs to handle the types of workloads for which they were designed OpenCL can efficiently share resources with OpenGL - Textures, Buffer Objects and Renderbuffers - Data is shared, not copied - OpenCL objects are created from OpenGL objects - clcreatefromglbuffer(), clcreatefromgltexture2d(), clcreatefromglrenderbuffer() 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 Copyright Khronos Group, Page 14

15 AMD Stands fully behind OpenGL Full OpenGL 3.0 (including extension pack) by Q Staged rollout between now and end of 2008 Intel is excited about OpenGL Look for Intel support of OpenGL 3.0 on future platforms NVIDIA has released OpenGL 3.0 beta drivers - For Windows XP and Vista on G80 and higher GPUs - Most of the extensions supported - Available for download at Copyright Khronos Group, Page 15

16 OpenGL 3.0 Extensions EXT_gpu_shader4 NV_conditional_render ARB_color_buffer_float NV_depth_buffer_float ARB_texture_float EXT_packed_float EXT_texture_shared_exponent NV_half_float ARB_half_float_pixel EXT_framebuffer_object EXT_framebuffer_multisample EXT_framebuffer_blit EXT_texture_integer EXT_texture_array EXT_packed_depth_stencil EXT_draw_buffers2 EXT_texture_compression_rgtc EXT_transform_feedback APPLE_vertex_array_object EXT_framebuffer_sRGB APPLE_flush_buffer_range (modified) In Current GPUs but not yet core EXT_geometry_shader4 (now ARB) EXT_bindable_uniform NV_gpu_program4 NV_parameter_buffer_object EXT_texture_compression_latc EXT_texture_buffer_object (now ARB) NV_framebuffer_multisample_coverage NV_transform_feedback2 NV_explicit_multisample NV_multisample_coverage EXT_draw_instanced (now ARB) EXT_direct_state_access EXT_vertex_array_bgra EXT_texture_swizzle Plenty of proven OpenGL extensions for OpenGL Working Group to draw upon for OpenGL 3.1 Copyright Khronos Group, Page 16

17 OpenGL 3.0 is here now - Big step forward in core functionality State-of-the-art support for latest programmable 3D hardware - Estimated 100 million OpenGL 3.0-capable GPUs shipped OpenGL 3.0 defines profiles and deprecation - To enable the specification to evolve more effectively OpenGL and OpenCL integrate compute and graphics - Unleashing new generations of visual applications Copyright Khronos Group, Page 17

18 Details and Examples Copyright Khronos Group, Page 18

19 Texture representation - Texture arrays: indexed access to a set of 1D or 2D texture images Texture formats - Floating-point texture formats - Single-precision (32-bit, IEEE s23e8) - Half-precision (16-bit, s10e5) - Red & red/green texture formats - Intended as FBO framebuffer formats too - Compressed red & red/green texture formats - Shared exponent texture formats - Packed floating-point texture formats Copyright Khronos Group, Page 19

20 Conventional texture - One logical pre-filtered image Texture array - An array of mipmap sets, a plurality of pre-filtered images - No filtering between mipmap sets in a texture array - All mipmap sets in array share same format/border & base dimensions - Both 1D and 2D texture arrays - Require shaders, no fixed-function support Texture image specification - Use glteximage3d, gltexsubimage3d, etc. to load 2D texture arrays - No new OpenGL commands for texture arrays - 3rd dimension specifies integer array index - No halving in 3rd dimension for mipmaps - So x17 reduces to all the way to Copyright Khronos Group, Page 20

21 Multiple skins packed in texture array - Motivation: binding to one multi-skin texture array avoids texture bind per object Texture array index Mipmap level index Copyright Khronos Group, Page 21

22 Shared exponent & packed float representations are ideal of High Dynamic Range (HDR) applications Copyright Khronos Group, Page 22

23 Packed float format - No sign bit, independent exponents bit 31 bit 0 5-bit exponent 5-bit mantissa 5-bit exponent 6-bit mantissa 5-bit exponent 6-bit mantissa Shared exponent format - No sign bit, shared exponent, no implied leading 1 bit 31 bit 0 5-bit shared exponent 9-bit mantissa 9-bit mantissa 9-bit mantissa Copyright Khronos Group, Page 23

24 Basic 1-component block compression format - Borrowed from alpha compression scheme of S3TC 5 2 min/max values + 16 bits Encoded Block 8-bit A 8-bit B 4x4 Pixel Decoded Block 64 bits total per block 16 pixels x 8-bit/componet = 128 bits decoded so effectively 2:1 compression Copyright Khronos Group, Page 24

25 Framebuffer objects - Standardized framebuffer objects (FBOs) for rendering to textures and renderbuffers - Render-to-texture - Multisample renderbuffers for FBOs Framebuffer operations - Copies from one FBO to another, including multisample data - Per-color attachment color clears, blending, and write masking Framebuffer formats - Floating-point color buffers - Floating-point depth buffers - Rendering to framebuffer format with 3 small unsigned floating-point values packed into 32-bits - Rendering into srgb color space framebuffers Copyright Khronos Group, Page 25

26 Problem: Display devices have non-linear (srgb) display gamut - Delicate color shading looks wrong Conventional rendering (uncorrected color) Gamma correct (srgb rendered) Unnaturally deep facial shadows Softer and more natural NVIDIA s Adriana GeForce 8 Launch Demo Copyright Khronos Group, Page 26

27 Color space standard - Intended for monitors, printers, and the Internet - Created cooperatively by HP and Microsoft - Non-linear, roughly gamma of Intuitively encodes more dark values OpenGL 2.1 already added srgb texture formats - Texture fetch converts srgb to linear RGB, then filters - Result takes more than 8-bit fixed-point to represent in shader 3.0 adds complementary srgb framebuffer support - srgb correct blending converts framebuffer srgb to linear, blend with linear color from shader, then convert back to srgb - Works with FrameBuffer Objects (FBOs) srgb chromaticity Copyright Khronos Group, Page 27

28 Vertex array configuration - Objects to manage vertex array configuration client state - Half-precision floating-point vertex array formats Vertex output streaming - Stream transformed vertex results into buffer object data stores Occlusion culling - Skip rendering based on occlusion query result Copyright Khronos Group, Page 28

29 Geometry shaders + transform feedback 1. Render quads (use 4-vertex line adjacency primitive) from vertex buffer object 2. Fetch height field 3. Stream subdivided positions and normals to transform feedback other buffer object 4. Use buffer object as vertex buffer 5. Repeat, ping-pong buffer objects Computation and data all stays on the GPU! Copyright Khronos Group, Page 29

30 Capture & re-use geometric deformations Transform feedback allows the GPU to calculate the interactive, deforming elastic skin of the frog Copyright Khronos Group, Page 30

31 Uses geometry shader silhouette edge detection geometry shader Complete mesh Useful for non-photorealistic rendering: Looks like human sketching Silhouette edges Copyright Khronos Group, Page 31

32 Generate fins for lines Generate shells for fur rendering Copyright Khronos Group, Page 32 Shimmering point sprites

33 Using geometry shader functionality Quadratic normal interpolation True quadrilateral rendering with mean value coordinate interpolation Copyright Khronos Group, Page 33

34 glbegin(gl_quads); glcolor3fv(red); glvertex3fv(lowerleft); glcolor3fv(green); glvertex3fv(lowerright); glcolor3fv(red); glvertex3fv(upperright); glcolor3fv(blue); glvertex3fv(upperleft); glend(); Geometry shader actually operates on 4- vertex GL_LINE_ADJACENCY primitives instead of quads Wrong, backslash triangle split Wrong, slash triangle split Better: Mean value coordinates Copyright Khronos Group, Page 34

35 OpenGL OpenGL buffer object GLuint bufferobj clcreatefromglbuffer OpenCL OpenCL buffer object cl_mem OpenGL texture 2D object GLenum target GLuint texture GLint miplevel OpenGL texture 3D object GLenum target GLuint texture GLint clcreatefromgltexture2d clcreatefromgltexture3d OpenCL 2D image object cl_mem OpenCL 3D image object cl_mem OpenGL renderbuffer object GLuint renderbuffer clcreatefromglrenderbuffer 2D image object cl_mem Copyright Khronos Group, Page 35

36 Requirements for OpenGL object sharing with OpenCL - OpenCL context must be created with an OpenGL context - Each platform-specific API will provide appropriate way to create an OpenGL-compatible CL context - For WGL (Windows), CGL (OS X), GLX (X11/Linux), EGL (OpenGL ES), etc. Creating cl_mem for GL Objects does two things - Ensures CL has a reference to the GL objects - Provides cl_mem handle to acquire GL object for CL s use clretainmemobject & clreleasememobject - can create counted references to cl_mem objects Copyright Khronos Group, Page 36

37 Still must enqueue acquire GL objects for compute kernels to use them - Otherwise reading or writing GL objects with CL is undefined - Enqueue acquire and release provide sequential consistency with GL command processing Enqueue commands for GL objects - clenqueueacquireglobjects - Takes list of cl_mem objects for GL objects - and list of cl_events that must complete before acquire - Returns a cl_event for this acquire operation - clenqueuereleaseglobjects - Takes list of cl_mem objects for GL objects - and list of cl_events that must complete before release - Returns a cl_event for this release operation Copyright Khronos Group, Page 37

38 Buffers in the context of the OpenGL pipeline Array Element Buffer Object (VeBO) Vertex Array Buffer Object (VaBO) glbegin, gldrawelements, etc. Vertex Puller Texture Buffer Object (TexBO) texel data Transform Feedback Buffer (XBO) Parameter Buffer (PaBO) vertex data Bindable Uniform Buffer (BUB) parameter data (not ARB functionality yet) Vertex Shading Geometry Shading Fragment Shading Framebuffer Texturing gldrawpixels, glteximage2d, etc. Pixel Pipeline glreadpixels, etc. Pixel Unpack Buffer (PuBO) Pixel Pack Buffer (PpBO) pixel data Copyright Khronos Group, Page 38