test(cull): add unit test for bounds rebuild on level switch

tests/cull.test.ts

@@ -77,6 +77,30 @@ describe('视口剔除', () => {
     expect(intersects(buildBounds([drawable(120, 0, 1, 1)]), 0, view)).toBe(true)
     expect(intersects(buildBounds([drawable(140, 0, 1, 1)]), 0, view)).toBe(false)
   })
+
+  test('换关卡时重建包围盒避免越界误剔除', () => {
+    // 模拟从 57x41 关卡（2337 个图元）切换到 80x80 关卡（6400 个图元）
+    const smallLevelDrawables = Array.from({ length: 2337 }, (_, i) => drawable(i * 10, 0, 80, 40))
+    const largeLevelDrawables = Array.from({ length: 6400 }, () => drawable(0, 0, 80, 40))
+
+    const view = viewportRect(0, 0, 1280, 720, 1)
+
+    // 旧实现未重建 bounds，largeLevel 使用 smallLevel 的 stale bounds
+    const staleBounds = buildBounds(smallLevelDrawables)
+    let visibleWithStaleBounds = 0
+    for (let i = 0; i < largeLevelDrawables.length; i += 1) {
+      if (intersects(staleBounds, i, view)) visibleWithStaleBounds += 1
+    }
+    expect(visibleWithStaleBounds).toBeLessThanOrEqual(2337)
+
+    // 修复后重建 bounds，所有落在视口内的图元正确通过剔除
+    const freshBounds = buildBounds(largeLevelDrawables)
+    let visibleWithFreshBounds = 0
+    for (let i = 0; i < largeLevelDrawables.length; i += 1) {
+      if (intersects(freshBounds, i, view)) visibleWithFreshBounds += 1
+    }
+    expect(visibleWithFreshBounds).toBe(6400)
+  })
 })
 
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