This example demonstrates composable context wrappers for custom geographic projections in D3. It shows how d3.geoPath’s streaming geometry output can be intercepted at multiple stages—first through a radians-and-rotate context, then through a project-and-transform context, and finally through an antimeridian-intersection handler that splits lines crossing the ±180° meridian. The projection.line method chains these contexts to convert spherical coordinates to planar canvas coordinates. The code relies on D3’s geo-projection internals and the Canvas 2D context, illustrating a low-level approach for building tailored projection pipelines.