Release God's Eye View as open source

src/data/cockpitAirLod.js

@@ -0,0 +1,35 @@
+/**
+ * Derive the AIR-contact near band for Cockpit presentation.
+ *
+ * This state is deliberately independent from 3D model admission. A contact
+ * inside the band stays an aircraft silhouette even when 3D is off, its model
+ * is still loading, or the model budget is full. Contacts outside the band are
+ * compact dots. Retained contacts use the wider KEEP radius so crossing the
+ * ADD boundary cannot make the visual oscillate.
+ *
+ * @param {Set<string>} previousIds - Contacts retained by the prior update.
+ * @param {Iterable<[string, number]>} distancesSquared - Contact id and squared distance in metres.
+ * @param {number} addDistanceM - Radius for contacts entering the near band.
+ * @param {number} keepDistanceM - Radius for contacts already in the near band.
+ * @returns {Set<string>} The next near-contact set.
+ */
+export function nextCockpitNearContacts(
+  previousIds,
+  distancesSquared,
+  addDistanceM,
+  keepDistanceM,
+) {
+  const previous = previousIds instanceof Set ? previousIds : new Set();
+  const addSq = Math.max(0, Number(addDistanceM) || 0) ** 2;
+  const keepSq = Math.max(addSq, (Math.max(0, Number(keepDistanceM) || 0) ** 2));
+  const next = new Set();
+
+  for (const [id, distanceSq] of distancesSquared || []) {
+    if (!id || !Number.isFinite(distanceSq) || distanceSq < 0) continue;
+    const limitSq = previous.has(id) ? keepSq : addSq;
+    if (distanceSq <= limitSq) next.add(id);
+  }
+
+  return next;
+}
+