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Spider GL A JavaScript 3D Graphics Library for Next-Generation WWW

Spider GL A JavaScript 3D Graphics Library for Next-Generation WWW. Marco Di Benedetto, Federico Ponchio, Fabio Ganovelli, Roberto Scopigno Visual Computing Lab – ISTI – CNR. 3D Content and the WWW. Many attempts have been done so far ActiveX objects

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Spider GL A JavaScript 3D Graphics Library for Next-Generation WWW

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  1. SpiderGLA JavaScript 3D Graphics Libraryfor Next-Generation WWW Marco Di Benedetto, Federico Ponchio, Fabio Ganovelli, Roberto Scopigno Visual Computing Lab – ISTI – CNR

  2. 3D Content and the WWW • Many attempts have been done so far • ActiveX objects • Proprietary browser extensions or plug-ins • Most libraries/plugins are too high level to directly access underlying graphics system • Developers forced to comply to some paradigm (scene graphs) • CG experts often find limitations due to high-level abstraction • Standardization needed • WebGL : JavaScript bindings to OpenGL|ES 2.0 Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  3. Outline Introduction to the WebGL Rendering Pipeline The SpiderGL Library Case Study: Mesh Rendering Library Features & Demos Conclusions & Future Work Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  4. What is WebGL • Actually what will be (standardization in progress) • Specification owned by the Khronos Group • Supported (and defined) by all major web browsers devs • JavaScript bindings to OpenGL|ES 2.0 • Almost 1-to-1 mapping, some modifications to meetJS developers’ habits and security issues • Enables home computers and mobile devices to natively access 3D content directly from web pages(no external plug-ins) Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  5. OpenGL|ES 2.0 • Stripped version of OpenGL, focused on Embedded Systems • Programmable : NO fixed function pipeline • Immediate mode (glBegin / End)  Use vertex / index buffers • Transform Stage (matrix stacks)  Explicit shaders uniforms • Lighting (lighting model, light sources, materials)  Lighting computation through shaders code • Named vertex attributes (glVertexPointer(…), …)  Generic attributes through glVertexAttribPointer(index, …) • Data entirely resides on GL resources (buffers, textures) • Buffer Centric API • Restrictions • Texture formats, data types, shading language limitations, ... Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  6. OpenGL|ES 2.0: Architecture (simplified) Data Memory Vertex Attributes Stream Index Stream VB IB TEX RB FB … 0 N-1 Code Memory VS FS UNI Vertex Puller Primitive Assembler & Rasterizer Fragment Processor Vertex Processor Texture Units Uniforms … 0 M-1 Output Merger Framebuffer Pixel Operations Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles Screen

  7. OpenGL|ES 2.0: API Structure • Context • Capabilities Query • Error Query • Creation / Activation / Destruction not part of specifications (EGL for this) • Objects • Resources creation / edit / bind / destruction • Data Set & Get • Configurable Stages • Enable / Disable • Constants / Parameters Set & Get • Programmable Stages • Accept user-defined programs (shaders) • Vertex Pipeline • Geometric primitives draw (activate Vertex Puller) • Pixel Pipeline • Framebuffer clear & readback (activate Pixel Operations) • Synchronization • Command Buffer flush & wait PipelineConfiguration & Data Execution Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  8. Motivations: Bring CG to the WWW • WebGL as a link between Web and CG developers • But... it’s very low-level! • Gaps to be filled: • Speed, of course • Algebraic and Geometric structures & algorithms • Asynchronous data fetch facilities • Assets loading • Ease the use of WebGL • SpiderGL aims at filling these gaps Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  9. SpiderGL: 3D Graphics for WWW • Lightweight LGPL library ( http://spidergl.org ) • provides typical CG data structures & algorithms • Sits on top of WebGL for realtime rendering • Goals: • Efficiency • asymptotic bounds are not the only concern • Simplicity & Short Learning Time • Key for fast application coding • Flexibility • Help with common tasks and create a robust middle layer for more complicated designs Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  10. Leading desing considerations • Using a third-party library should be easy • Do not impose any design choice a priori • Avoid over-abstraction • In CG simple and self-contained types works very well • Users must be able to reuse as much as possible of their former knowledge on the subject • All the entities have de-facto standardized names and behavior • Experienced users often want fine control  low-level access Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  11. SpiderGL Architecture Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles • GL: rendering • Mesh: editable or renderable 3D model • Space: geometric s. & a. • Async: asinchronous data requests managing • UI: user and html interface

  12. Case Study: Mesh Rendering Vertex & Index Buffers Shaders & Uniforms • How a typical 3D model is represented: • A list of vertices (each vertex is a bundle of data) • A list of vertex indices, specifying how they are connected to form basic geometric primitives (points, segments, triangles) • What we need to draw it • POV intrinsic and extrinsic parameters • Some procedure to make light sources and model material interact to form colors on the final image Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  13. Meshes in SpiderGL • Mesh Structure • Set of named vertex attribute streams(position, normal, color, custom, ...) with NO predefined semantic • Set of named array or indexed primitive streams(points list, triangulated surface indices, wireframe segments, ...) • Mesh twins: • SglMeshJS: an editable data structure • SglMeshGL: a renderable graphics resource • Unified interface, conversion functions Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  14. Create a Renderable Mesh /*******************************************************************/ var mesh = new SglMesh(gl); // add a vertex attribute named “position” (type is inferred) mesh.addVertexAttribute("position", 3, nativePositions); // add a NORMALIZED vertex attribute named “color” mesh.addVertexAttribute("color", 3, nativeColors, true); // add connectivity information named “triangles” (type is inferred) mesh.addIndexedPrimitives("triangles", gl.TRIANGLES, nativeIndices); // add “array” primitives named “vertices” mesh.addArrayPrimitives("vertices", gl.POINTS, 0, 3); /*******************************************************************/ Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  15. Create a Shader Program /*******************************************************************/ // vertex shader source code string var vertSource = ""; vertSource += “uniform mat4 u_mvp; \n"; vertSource += "..."; vertSource += "attribute vec3 a_position; \n"; vertSource += "attribute vec3 a_color; \n"; vertSource += "..."; // fragment shader source code string var fragSource = "..."; // program setup var prog = new SglProgram(gl, [vertSource], [fragSource]); /*******************************************************************/ Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  16. Stream Mapping • The mesh has 2 vertex attribute streams (position & color) • The vertex shader has 2 input vertex attributes •  A correspondence between the two sets must be established /**********************************************************/ … … … mesh.addVertexAttribute("position", 3, nativePositions); mesh.addVertexAttribute("color", 3, nativeColors, true); … … … /**********************************************************/ /**********************************************/ … … … vertSource += "attribute vec3 a_position; \n"; vertSource += "attribute vec3 a_color; \n"; … … … /**********************************************/ Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  17. Rendering /*******************************************************************/ // <name : string>  connect shader attr “name” to mesh attr “string” var streamMapping = { a_position : "position", a_color : "color" }; // <name : value>  set program uniform “name” to value “value” var uniforms = { u_mvp : getModelViewProjectionMatrix() }; // utility function (full control available through SglMeshRenderer) sglRenderMeshPrimitives(mesh, "triangles", prog, streamMapping, uniforms); /*******************************************************************/ Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  18. Option Parameters /*********************************************************/ var textureOpts = { minFilter : gl.LINEAR_MIPMAP_LINEAR, generateMipmap : true, onload : function () { ... } }; // create texture from remote image var tex = new SglTexture2D(gl, "image_url", textureOpts); /*********************************************************/ • The GL module aims at simplifying common WebGL tasks • Creation of WebGL objects • Textures, programs, framebuffers, ... • Common sequence of several commands • SpiderGL offers reasonable but overridable defaults Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  19. Dealing with WebGL Objects • Contstructors: SpiderGL provides easy-to-use configurable functions to create WebGL Objects • Wrappers: each native handle can be wrapped by optimized high-level objects • Flexibility: experienced users may want direct low-level control: • obj.handle native WebGL object • obj.synchronize()  update state after low-level usage Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  20. Overcoming Mesh Limitations • Ex.: OpenGL|ES 2.0 (and so WebGL) does not allow 32 bit vertex indices •  Limited to 64K vertices per chunk • SpiderGL uses packed-indexed primitive stream to seamlessly allow very large meshes • Mesh is automatically subdividedinto sub-meshes Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  21. On the Math / Geometry Side • Support CG-related linear algebra entities • 2, 3, 4-dimensional vectors, 2x2, 3x3, 4x4 matrices, quaternions • Two choices: operate on native JS arrays or boxing objects • Standard geometric entities • Planes, spheres, boxes, ... • Intersection queries • Transformation Stack • Editable Mesh (SglMeshJS) • Several (and more coming) algorithms on trimeshes Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  22. Assets, Asynchronous Fetch and UI • COLLADA, OBJ, JSON (and more coming) importers • Every kind of handled document can be loaded with a uniform asynchronous request interface • Images, 3D Models, shaders code, ... • Dynamic priority queues for multiresolution • Requests can be interrupted, priority can change, transfer callbacks can be installed • Special watcher object for completion of batched transfers • GLUT-like interface and Interactors • first-person camera, trackball, ... Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  23. What can be done with SpiderGL I’m tired up here... Let’s see some demos! http://spidergl.org/code.php Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  24. SpiderGL to Assist Content Creation • Multimedia Web repositories are widespread • Images, Video, Audio, Text, ... • What about 3D Repositories? • WebGL will bring HW Accelerated 3D Graphics to WWW • Lots of 3D databases • We need an effective way to deploy content to users • MeShade: a content authoring tool • Let’s have a look! • http://spidergl.org/meshade/index.html Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  25. Conclusions • SpiderGL as a Geometry processing and Visualization library • Do not over-abstract graphics objects, ease the completion of common task, allow low-level access • Real-time performances with WebGL with several case studies • Future Work: • Continuous improvements, growing set of algorithms • Toward an automated process to make high-end 3D contentto be available to handheld devices Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

  26. Thank You! http://spidergl.org Questions? marco.dibenedetto@isti.cnr.it Di Benedetto et al. - SpiderGL: A JavaScript 3D Graphics Library for Next-Generation WWW - Web3D 2010 Los Angeles

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