Function stroke_line_styled 

pub fn stroke_line_styled(
    coords: &[GeoCoord],
    half_width: f64,
    cap: LineCap,
    join: LineJoin,
    miter_limit: f32,
) -> StrokeLineResult

Expand a polyline into a thick triangle ribbon with proper line caps, line joins, per-vertex extrusion normals, and cumulative distances.

This is the richer counterpart of stroke_line. The additional outputs enable the GPU line shader to evaluate dash patterns (via distances) and perform antialiasing (via normals), while the tessellation itself produces correct cap and join geometry.

Parameters

• coords — polyline vertices in (lon, lat) degree space.
• half_width — extrusion half-width in the same degree-space units.
• cap — line cap style applied at both endpoints.
• join — line join style applied at interior vertices.
• miter_limit — ratio threshold for automatic miter → bevel fallback.