Show HN: Understanding the Spatial Web Browser Engine

Summary

Understanding the Spatial Web Browser Engine 1. What Is a Spatial Web Browser? A Spatial Web Browser is a user agent that loads, interprets, and presents Web content (HTML, CSS, JS, WebGL/WebGPU, WebXR, media) directly inside a 3D coordinate space instead of flattening everything onto a 2D rectangular viewport. Every DOM element (text nodes, images, canvas, form controls, SVG, etc.) can be:Positioned, rotated, and scaled in world / XR reference spacesLayered with true depth ordering (not just z-index compositing) for stereoscopic correctnessInteracted with using spatial input sources (gaze, hands, controllers, future: eye tracking, anchors)Composed alongside native 3D assets (GLTF models, environment maps) in one unified frame loopIn short: a Spatial Web Browser lets "regular Web pages" become immersive 3D experiences without abandoning open Web standards.2. Why Not Just Extend an Existing (Classic) Browser? Traditional engines (Blink, Gecko, WebKit) are extraordinarily capable—but architecturally optimized for 2D document + compositor pipelines. Retrofitting full 3D spatial semantics collides with deep assumptions:XR Spatial Integration Requirements: In XR systems, we need to seamlessly integrate Web content with other Unity/Unreal 3D engine content in spatial environments, which traditional browsers' 2D architecture cannot satisfy.Full 3D Element Design: Inspired by visionOS, in Spatial Web, we need all elements to have true 3D spatial properties rather than being confined to a flat plane, requiring a complete architectural redesign from the ground up.Therefore JSAR pursues a purpose-built Spatial Web Browser Engine rather than modifying an existing one.This approach contrasts with the evolutionary path taken by visionOS Safari, which gradually introduces spatial features like HTMLModelElement for 3D model display and Spatial Photo support for stereoscopic images. While visionOS represents a progressive enhancement of traditional browser engines toward spatial cap...