Webium

A JS-first web rendering engine for game engines — parse and render HTML, CSS, and JavaScript natively inside Unity, Godot, or any C# game engine through a shared TypeScript core, pluggable rendering backends, and a pluggable JS runtime.

Status

v0.2.0 — Dual backend support (UGUI + UIElements) with improved CSS rendering fidelity. Both backends render a functional hello-world example with accurate native text measurement, margin collapsing, font-family mapping, and generic CSS property application. The TypeScript core (@webium/core) owns the DOM, CSS pipeline, event system, layout, reconciliation, and bridge protocol. C# is a thin bridge layer with pluggable render backends selectable via WebiumSurfaceConfig.

Architecture

┌─────────────────────────────────────────────────┐
│              @webium/core (TypeScript)           │
│  VirtualDOM · CSS Pipeline · Events · Layout    │
│  Reconciliation · Modding · Bridge Protocol     │
└──────────────────────┬──────────────────────────┘
                       │ RenderCommand / InputEvent
┌──────────────────────▼──────────────────────────┐
│              C# Bridge Layer                     │
│  IRenderCommandExecutor · IInputEventForwarder   │
│  ILifecycleDriver · ILayoutReadbackNew           │
│  ITextMeasurer · IWebiumRenderBackend            │
└──────────────────────┬──────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────┐
│           Engine Backends (C#)                   │
│  UGUI Backend · UIElements Backend · (future)    │
│  UGUI Backend · UIElements Backend · (future)    │
└─────────────────────────────────────────────────┘

er direction). This decouples core logic from any specific engine and makes multi-engine support straightforward.

Packages

| Package | Language | Description | | Webium.Core | C# | Bridge interfaces (IRenderCommandExecutor, IInputEventForwarder, ILifecycleDriver, ILayoutReadbackNew, ITextMeasurer, IWebiumRenderBackend) and shared types (RenderCommand, RenderOp, RenderBackendType) | | @webium/core | TypeScript | HTML parser, browser API surface (document/element/event), virtual DOM, CSS cascade/specificity/selectors, events (capture/target/bubble), Yoga layout, reconciliation engine, modding (manifest parser, CSS scoper, mod manager), render command + input event bridge protocol | | Webium.Unity.Runtime | C# | Unity rendering backends — UGUI (UGUIRenderBackend) and UIElements (UIElementsRenderBackend), ReconciliationLoopBehaviour, UnityPuerTSRuntime (real PuerTS runtime adapter), native text measurers |enderBackendType) | | Webium.JSRuntime| C# |IJSRuntime/IJSBridge interfaces and engine-agnostic stubs (PuerTSRuntimeis a stub for thedotnet test` pipeline) |

Next Milestone

v0.3.0 — Interactivity & Richer CSS. More complex examples to expand CSS support (borders, border-radius, opacity, pseudo-classes) and add JS interactivity (button clicks with DOM mutations, text input fields, dynamic element creation/removal). See ROADMAP.md for details.