This is a monorepo for maptalks.js, a comprehensive browser-based 2D/3D mapping and GIS rendering engine. The system provides interactive web maps with support for vector tiles (MVT), 3D tiles (I3S, Cesium 3D Tiles), GLTF/GLB models, terrain elevation, and spatial analysis (viewshed, cut, flood, skyline). It features a dual rendering backend: a Canvas2D renderer for basic maps and a WebGL/WebGPU renderer with a modular shader system (reshader) supporting PBR materials, lighting, shadows, bloom, fog, rain, and post-processing effects. The architecture is a monorepo with pnpm workspaces and Turbo, containing over 20 packages including core map engine (maptalks), GL rendering framework (gl), vector tile layer (vt), 3D analysis (analysis), traffic simulation (traffic), GLTF loader, 3D tiles layer, and WebGL sandbox (fusion.gl). Key entry points are the Map class, layer classes (VectorTileLayer, Geo3DTilesLayer, GLTFLayer), and analysis tools. Data flows involve fetching tiles/models from remote sources, parsing in workers (Web Workers for tile building, GLTF decoding, terrain processing), and rendering via the shader pipeline. External dependencies include gl-matrix for math, @mapbox/vector-tile for MVT parsing, and various WebGL/WebGPU APIs. The codebase is actively maintained with frequent commits, but shows medium technical drift due to dual shader language maintenance (GLSL + WGSL), some duplicated utility code across packages, and commented-out or deprecated features.