This file demonstrates computing line segment intersections off the main thread using a Web Worker. It defines a worker script that processes intersection requests and posts results back, while the main thread initializes the worker, sends coordinate data, and renders the results as GeoJSON on the map. The pattern is a clean example of isolating a computationally expensive geometry operation (finding all pairwise intersections among random segments) into a background worker to avoid UI blocking. It could be extracted and repurposed for any application requiring client-side geometric intersection calculations, requiring only minor parameterization of the worker input/output.

This example implements the 'four-parameter' coordinate transformation (translation, rotation, scale) to align a CAD map with web map coordinates (e.g., Internet map as base). The code uses `vjmap.coordTransfromGetFourParamter` to compute the transformation from user-defined control points, then overlays the CAD map as a WMS layer with the computed parameters. The pattern is a reusable solution for georeferencing arbitrary CAD drawings to real-world coordinates, a common GIS integration problem. The logic for selecting control points, computing parameters, and applying the transformation is self-contained and could be extracted into a standalone utility.