From 692ee057ab114c9fbc40d48efd690d0eee193c46 Mon Sep 17 00:00:00 2001
From: gaozheng <gaozheng.cn@gmail.com>
Date: Wed, 17 Jun 2026 15:45:57 +0800
Subject: [PATCH] =?UTF-8?q?fix(vtk):=20=E7=93=A6=E7=89=87=E8=A7=86?=
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---
 src/app/TileBasemap.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/app/TileBasemap.cpp b/src/app/TileBasemap.cpp
index 4535bb6..8b2c8fa 100644
--- a/src/app/TileBasemap.cpp
+++ b/src/app/TileBasemap.cpp
@@ -223,9 +223,11 @@ void TileBasemap::refineTile(int z, int x, int y, std::set<long long>& out, int&
     const auto sw = frame_->toLocal(b.south, b.west);
     const auto ne = frame_->toLocal(b.north, b.east);
 
-    // 视锥剔除：瓦片 AABB 全在某视锥面外侧 → 不在视野内，直接丢弃(否则会在屏幕外乱细分耗尽预算)。
+    // 视锥剔除：瓦片 AABB 全在某侧面外侧 → 不在视野内，丢弃(否则屏幕外乱细分耗尽预算)。
+    // 只用 4 个侧面(左右上下)，不用近/远裁剪面——远裁剪面随已加载几何变化，
+    // 首帧底图未齐时远面贴得近会误剔除远处可见瓦片(等多久都不出、微动才出)。
     const double zmin = -1000.0, zmax = 1000.0;  // 地形起伏远小于瓦片尺度，给宽松 z 带
-    for (int p = 0; p < 6; ++p) {
+    for (int p = 0; p < 4; ++p) {
         const double* pl = &frustum_[p * 4];  // 内法向：内侧 a·x+b·y+c·z+d ≥ 0
         const double vx = pl[0] >= 0 ? ne.x : sw.x;  // 取最朝法向的角点(p-vertex)
         const double vy = pl[1] >= 0 ? ne.y : sw.y;