WebXR in Android and Linux with OpenXR

WebXR in Android and Linux with OpenXR

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  WebXR in Android& Linux with OpenXR WebKit Contributors Meeting 2025 28-29 October 2025 Sergio Villar Senín svillar@igalia.com 1 / 16
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  W3C API forXR content in the Web Core Spec + extension Modules (AR, hit testing, plane detection, light estimation...) Adopted by all major engines: Gecko (no AR, unmaintained), Blink (most complete) and WebKit Rendering via WebGL/WebGL2 or WebGPU WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 2 / 16
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  Khronos API tointeract with XR devices Device, platform and gfx library agnostic OpenGL(ES), Vulkan, D3D (and Metal in 1.1.x) Implemented by OpenXR runtimes (internally they can use vendor specific APIs/libraries) Solves the fragmentation problem in XR world Widely adopter by most vendors (Meta Quest, Pico, Magic Leap 2, AndroidXR, Qualcomm, HoloLens...) WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 3 / 16
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  📜WebXR in WebKit Igaliastarted to implement the spec in March 2020 Added support for the WebXR Core & Test APIs Eventually paused the investment XR devices were Android only and WPE/GTK Linux only OpenXR not widely adopted, vendors still using propietary SDKs Apple took over and redesigned it (multiprocess architecture) WebXR available in the wild in VisionOS Igalia resumed WebXR work in GTK/WPE due to client request (WPE for Android available) WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 4 / 16
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  WebXR Rendering Pipeline WebXRin Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 5 / 16
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  WebXR Rendering Pipeline 1.UIProcess access XR devices and provides data to WebProcess (poses, device features...) 2. UIProcess creates the images[^1] where content is rendered 3. UIProcess shares images with WebProcess 4. WebProcess imports them images and renders content on them 5. WebProcess signals UIProcess when the content is ready (fences) ^1: images are OpenGL textures, Vulkan images, Android surfaces... WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 6 / 16
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  Rendering Pipeline &OpenXR OpenXR provides a swapchain that generates images OpenGL textures (2-3) exported to WebProcess using DMABuf (AHardwareBuffer) EGL fences used to signal UIProcess whenever frame is ready Currently using just 1 layer (projection layer) Code ready to support multiple layers (WebXR layers) WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 7 / 16
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  Rendering Pipeline Design Mostof code shared between Cocoa and WPE/GTK Flexible design: different framebuffers for drawing and displaying Required for MSAA: resolving multisampled buffers requires blit Allows framebuffer scaling Allows multiple layouts Shared: one texture for both eyes (GTK/WPE, VisionOS simulator) Layered: one texture per eye (VisionOS, OpenXR supports this too) WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 8 / 16
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  Rendering Pipeline Design(II) Images from UIProcess exported only once and cached in WebProcess to be used alternatively on every frame Shared layout is simpler and requires less blits Not supported by all platforms (VisionOS) Layered layout requires intermediate blit to single texture when using WebGL (expensive!) WebXR + WebGL assumes 1 texture shared by both eyes WebXR + WebGPU natively supports 1 texture per eye WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 9 / 16
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  Rendering Pipeline &Android DMABuf cannot be used to share images between processes 🤖Android Hardware Buffer is the (native) way to go ⚠️AHB allocates its own resources. Cannot use OpenXR images directly Extra blit from AHB -> OpenXR image required before sending content to XR compositor WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 10 / 16
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  Supported specs GTK&WPE WebXRDevice API WebXR Test API WebXR AR Module WebXR Hand Input Module WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 11 / 16
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  Demo 🎉 0:00 /0:22 WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 12 / 16
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  Further Improvements 🚊Use Vulkanas a transport mechanism 💨Fast path for non MSAA case ⏱️Instrumentation WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 13 / 16
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  What's Next for2026 WebXR Layers (initially without WebGPU bindings) WebXR Hit Testing (useful for <model-viewer>) WebXR Anchors WebXR in Android & Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 14 / 16
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  Questions WebXR in Android& Linux with OpenXR Igalia, WebKit Contributors Meeting 2025 15 / 16
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