Release v0.1.3 2026-07-11

src/game/arena.ts

@@ -0,0 +1,29 @@
+import type { BossMotionState, WorldPosition } from "./types";
+
+export const ARENA_CENTER: WorldPosition = [0, -1];
+export const ARENA_RADIUS = 8.35;
+export const ARENA_WALL_RADIUS = 9.55;
+
+export function clampToArena(position: WorldPosition, padding = 0): WorldPosition {
+  const radius = Math.max(0, ARENA_RADIUS - padding);
+  const dx = position[0] - ARENA_CENTER[0];
+  const dz = position[1] - ARENA_CENTER[1];
+  const distance = Math.hypot(dx, dz);
+  if (distance <= radius || distance < 0.0001) return [position[0], position[1]];
+  const scale = radius / distance;
+  return [ARENA_CENTER[0] + dx * scale, ARENA_CENTER[1] + dz * scale];
+}
+
+export function constrainBossMotion(motion: BossMotionState): BossMotionState {
+  return {
+    ...motion,
+    position: clampToArena(motion.position),
+    chargeStart: clampToArena(motion.chargeStart),
+    chargeEnd: clampToArena(motion.chargeEnd),
+    pounceCenter: clampToArena(motion.pounceCenter),
+  };
+}
+
+export function isInsideArena(position: WorldPosition, tolerance = 0.001) {
+  return Math.hypot(position[0] - ARENA_CENTER[0], position[1] - ARENA_CENTER[1]) <= ARENA_RADIUS + tolerance;
+}