Since 2009, Chrome has used SwiftShader to enable 3D rendering on systems that can’t fully support hardware-accelerated rendering. While 3D content like WebGL is written for a GPU, some users’ devices don’t have graphics hardware capable of executing this content. Others may have drivers with serious bugs which can make 3D rendering unreliable, or even impossible. Chrome uses SwiftShader on these systems in order to ensure 3D web content is available to all users.
Chrome running without SwiftShader on a machine with an inadequate GPU (left) cannot run the WebGL Globe experiment. The same machine with SwiftShader enabled (right) is able to fully render the content.
SwiftShader implements the same OpenGL ES graphics API used by Chrome and Android. Making SwiftShader open source will enable other browser vendors to support 3D content universally and move the web platform forward as a whole. In particular, unconditional WebGL support allows web developers to create more engaging content, such as casual games, educational apps, collaborative content creation software, product showcases, virtual tours, and more. SwiftShader also has applications in the cloud, enabling rendering on GPU-less systems.
To provide users with the best performance, SwiftShader uses several techniques to efficiently perform graphics calculations on the CPU. Dynamic code generation enables tailoring the code towards the tasks at hand at run-time, as opposed to the more common compile-time optimization. This complex approach is simplified through the use of Reactor, a custom C++ embedded language with an intuitive imperative syntax. SwiftShader also uses vector operations in SIMT fashion, together with multi-threading technology, to increase parallelism across the CPU’s available cores and vector units. This enables real-time rendering for uses such as app streamingonAndroid.
Developers can access the SwiftShader source code from its git repository. Sign up for the mailing list to stay up to date on the latest developments and collaborate with other SwiftShader developers from the open-source community.
Posted by Nicolas Capens, Software Engineer and Pixel Pirate
Rich, interactive experiences are a cornerstone of the web, but can sometimes take a long time to render due to their complexity. Currently, Chrome improves rendering performance by using heuristics to determine which parts of a page have changed. Only sections that have changed are updated instead of rendering the entire page 60 times per second. However, because elements can display outside the bounds of their parents, it is possible that changes to one element could affect elements anywhere else in the document. This dramatically increases the number of elements that Chrome must consider while rendering.
Collecting accurate real-user measurement (RUM) data is critical to detecting performance problems and regressions that may hurt the user experience of a site. Chrome's DevTools allow local site testing, but measuring how a site performs for real users with varied devices can be challenging. The latest version of Chrome supports the PerformanceObserver API, which enables a simple and performant way to collect RUM data at runtime. Instead of polling for updates, sites can declare which metrics they’re interested in. The browser notifies the site when new data points for those metrics become available.
Service Worker Responses Powered by ReadableStreams
Streaming HTTP responses allow browsers to progressively render earlier portions of a large HTML document before the entire response is available. The latest version of Chrome improves service workers by adding streaming support. Sites can use the Streams API to construct streamable Response objects by passing a ReadableStream to the Response constructor.
Push notifications have unlocked a new level of re-engagement for web apps, but until now developers have had to use proprietary push message delivery services and different APIs for different browsers. Chrome now supports VAPID, an open standard to authenticate a site’s server with a push service. When using VAPID, sites are given a Firebase Cloud Messaging endpoint, which supports the cross-browser web push protocol.
Other features in this release
Chrome now pauses animations while showing modal dialog boxes.
HTTP alternative services allow sites to specify additional origins that can be used to reach a certain resource, enabling easier protocol upgrades and load balancing.
Touch gestures inside a cross-origin iframe can no longer trigger popups unless they correspond to a tap gesture, preventing accidental pop-ups during scrolling.
The latest version of Chrome supports -webkit-appearance:none which disables the default rendering of HTML5 meter elements and allows easier custom CSS styling.
flexbox children with position:absolute will now be positioned using justify and align if the element does not have a left:, right:, top:, or bottom: position specified.
