Examples/Web — raylib-cs in the browser (WebAssembly)

Runs the raylib examples in the browser via WebAssembly, with a dropdown to switch between them. It proves the Raylib-cs NuGet package's browser-wasm support end-to-end: the package's buildTransitive targets link the shipped raylib.a into the .NET wasm runtime.

The browser-wasm configuration only activates when publishing with RuntimeIdentifier=browser-wasm; normal solution builds don't need the wasm-tools workload.

Prerequisites

.NET 10 SDK
dotnet workload install wasm-tools
Raylib-cs (works with the local project, or nuget if MSBuild property <UseRaylibCsPackage> is true

Build

dotnet publish Examples -f net10.0 -r browser-wasm -c Release
# -> Examples/bin/Release/net10.0/browser-wasm/AppBundle/

Toolchain caveat

If the link step fails with wasm-opt: Unknown option '--enable-bulk-memory-opt', the installed wasm-tools workload is out of sync with the SDK (stale workload band or a system EMSDK on PATH); fix with dotnet workload update. As a safety net, Examples.csproj defaults browser-wasm publishes to unoptimized native linking; an optimized publish can override those properties.

Run

WebAssembly must be served over HTTP (not file://):

dotnet serve -d Examples/bin/Release/net10.0/browser-wasm/AppBundle    # dotnet tool install -g dotnet-serve
# or:  npx http-server Examples/bin/Release/net10.0/browser-wasm/AppBundle

Open the printed URL and use the Example dropdown to switch examples.

Canvas scaling modes

The render buffer stays fixed at 800x450; display scaling is CSS-only. Pick with the Scale dropdown (or ?scale= query param):

native (default): exact 800x450 CSS pixels.
integer: largest whole-number multiple that fits, centered with letterboxing (pixel-perfect).
fit: fills the viewport preserving aspect ratio (can be fractional, less crisp).

Scaling is computed in device pixels and converted back to CSS via devicePixelRatio, so the modes behave consistently across OS scale and browser zoom. The status bar shows the live numbers (DPR, CSS size, backing size, scale): integer should stay crisp at any OS scale or zoom, and native should always report Scale 1.00.

How it works

A browser can't run raylib's blocking while (!WindowShouldClose()) loop (it would freeze the page), so frames are driven from JavaScript:

Host.Main() calls InitWindow once; main.js then populates the dropdown and selects the first example via Host.SetExample, so init failures surface in the on-page error banner.
main.js binds the page <canvas> to the runtime and calls Host.UpdateFrame() from a requestAnimationFrame loop paced to the current example's TargetFps (raylib's own limiter busy-waits and would peg the main thread). The Host methods it calls are [JSExport].
On switch, Host.SetExample unloads the previous example, resets the cursor to visible, and applies the next TargetFps. Cursor hiding and ConfigFlags are not honored in the browser. If Init or Update throws, the example is unloaded and an error banner is shown.
Each example is a single .cs file implementing IExample (Init / Update / Unload); the host owns the window, so examples never call InitWindow/CloseWindow. Platform differences (e.g. GLSL 100 vs 330) are handled inline with #if BROWSER guards, not separate files.

Adding more examples

Examples are auto-discovered by reflection (ExampleRegistry.DiscoverAll) — no list to edit. Drop a new .cs file in the matching category folder implementing IExample, splitting the original monolithic Main as:

Main() { <setup>; while(!WindowShouldClose()){ <body> } <cleanup> }
  ->  Init()  { <setup, minus InitWindow/SetTargetFPS> }   // loop-spanning locals become fields
      Update(){ <body> }                                   // keep BeginDrawing..EndDrawing
      Unload(){ <cleanup, minus CloseWindow> }

Keep the standalone static Main() as a thin driver so the example still runs on its own.

If an example can't run on single-threaded wasm, add its type to DesktopExcludedFromBrowser in ExampleRegistry.cs; BrowserOnly is the inverse list. Assets under resources/ are bundled into the wasm virtual filesystem automatically.

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