New Feature: Add API to draw a “direction cone” (sector shape) easily

[tungnk123]

Description

Currently, the Mapbox Maps SDK for Android does not provide a built-in way to render a direction cone (also known as a sector, view cone, or field-of-view arc). Developers must manually compute latitude/longitude points along an arc and create a polygon to visualize a directional area — for example, a Qibla direction cone or camera field of view.

This requires repetitive math and custom logic:

• Computing arc coordinates using spherical trigonometry
• Handling wrap-around at 0°/360° and anti-meridian crossings
• Creating polygons manually with PolygonAnnotation or FillLayer

Example use case

Visualizing directional areas such as:

• Camera or compass “view cones”
• Radar or sensor field of view
• Qibla direction cone from a user’s location

Suggested solution

Add a lightweight helper API to easily draw a directional cone centered on a Point, given:

• center: geographic point (latitude, longitude)
• bearing: direction in degrees
• halfAngle: cone spread in degrees
• radius: distance in meters or kilometers
• fillColor / fillOpacity: optional styling

Example usage

mapView.annotations.createDirectionCone(
    center = Point.fromLngLat(lon, lat),
    bearing = heading,
    halfAngle = 25.0,
    radius = 300000.0, // meters
    fillColor = Color.parseColor("#6600EEFF"),
    fillOpacity = 0.35
)

Expected behavior:

• SDK internally computes and renders the cone polygon
• Automatically handles projection and anti-meridian issues
• Provides consistent results across zoom levels and map projections

---

Why

Drawing a simple fan-shaped area currently requires non-trivial math and boilerplate, which developers have to reimplement in every project. A built-in API would:

• Simplify rendering of directional indicators
• Reduce code duplication across apps
• Improve maintainability and readability
• Enable new UX patterns (e.g., navigation view cones, AR guidance, Qibla direction indicators)