WebGl.Renderer

WebGL2 rendering backend for DIR.Lib's Renderer<TSurface>, hosted in Blazor WebAssembly. The browser sibling of SdlVulkan.Renderer — same drawing contract, same MTSDF text pipeline, same shared SdfFontAtlas core.

Architecture

• Command-buffer interop, not chatty GL calls. Every Renderer method synchronously appends fixed-stride opcode records + raw vertex floats to in-memory streams (WebGlContext); one Present() hands both to the JS shim (wwwroot/webgl-renderer.js) in a single [JSImport] call, and the shim replays them as gl.* calls. Atlas texture traffic rides a separate SyncAtlas call that fires only when glyph pages actually changed.
• Text is our own rasterizer, end to end. Glyphs come from DIR.Lib's managed ManagedFontRasterizer as MTSDF bitmaps, packed by the shared SdfFontAtlas core (framesInFlight: 1, synchronousRasterize: true for single-threaded WASM), uploaded via texSubImage2D, and drawn with the same median() + analytic-sdfEdge fragment shader as the desktop Vulkan renderer. No CSS fonts, no canvas text APIs.
• The GL/Vulkan NDC Y-flip lives in the JS-side projection matrix — shader bodies are byte-identical ports of VkPipelineSet's GLSL.
• Pre-bake a .sdfg glyph cache at build time (see SdfGlyphDiskCache), fetch it into the WASM in-memory FS, and startup performs zero rasterization.

Usage (Blazor WASM)

var renderer = await WebGlRenderer.CreateAsync("my-canvas", 760, 840);
renderer.Clear(background);
/* Renderer<WebGlContext> draw calls — FillRectangle, DrawText, ... */
renderer.Present();

The JS shim ships as a static web asset (_content/WebGl.Renderer/webgl-renderer.js) — no consumer wiring beyond the NuGet reference.

Tests

src/WebGl.Renderer.Tests runs headless on desktop .NET: command-stream encoding goldens, shader-source sanity, and real-font text encoding over a fake JS bridge. Real-browser compile/visual coverage happens in the consuming app (see the chess project's Chess.Web).