feat(packages): ludic.compass - bearing marks on a strip: marks gathered once a frame from an open registry of providers (CompassProviders), gated by the viewer's tier, sorted tracked / note / plain and culled to a cap; bearings and distances off the viewer's facing, the tracked mark, a capture that lets a guide hear the providers whatever the tier, the eight points, and the radar's range per tier with blips on a unit disc; the viewer through a port

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.compass/radar.ludic

@@ -0,0 +1,40 @@
+# radar.ludic - the radar's tiers: a range for each compass tier (0 is no radar), which marks it
+# shows, and where each falls on a unit disc with ahead at the top
+var cmp_ranges: []float = null
+var cmp_radar_from: int = 2     # marks of at least this tier are blips; the tracked one always is
+
+export function compass_config_radar(ranges: []float, from_tier: int) -> void {
+  cmp_ranges = new []float
+  for i in 0 .. len(ranges) { push(cmp_ranges, ranges[i]) }
+  cmp_radar_from = from_tier
+}
+
+# how far the radar reaches with the viewer's compass, 0 without one; a tier past the table has
+# the last range
+export function compass_radar_range() -> float {
+  if cmp_ranges == null or len(cmp_ranges) == 0 { return 0.0 }
+  let t = CompassWorld.tier()
+  if t < 0 { return 0.0 }
+  if t >= len(cmp_ranges) { return cmp_ranges[len(cmp_ranges) - 1] }
+  return cmp_ranges[t]
+}
+
+export function compass_radar_on() -> bool { return compass_radar_range() > 0.0 }
+
+# the i-th mark is a blip: a radar is carried, it is shown there and it is in range
+export function compass_radar_has(i: int) -> bool {
+  if i < 0 or i >= compass_count() or not compass_radar_on() { return false }
+  let m = cmp_list[i]
+  if m.tier < cmp_radar_from and m.prio < COMPASS_TRACKED { return false }
+  return compass_dist(i) <= compass_radar_range()
+}
+
+# where on a unit disc: x right, y down, so ahead is (0, -1) and the edge is the range
+export function compass_radar_x(i: int) -> float { return -Math.sin(compass_bearing(i)) * cmp_radar_frac(i) }
+export function compass_radar_y(i: int) -> float { return -Math.cos(compass_bearing(i)) * cmp_radar_frac(i) }
+
+function cmp_radar_frac(i: int) -> float {
+  let r = compass_radar_range()
+  if r <= 0.0 { return 0.0 }
+  return Math.min(compass_dist(i) / r, 1.0)
+}