src/app/TileBasemap.cpp

@@ -3,6 +3,7 @@
 #include <algorithm>
 #include <cmath>
 #include <cstring>
+#include <utility>
 
 #include <QDebug>
 #include <QImage>
@@ -43,6 +44,7 @@ constexpr int kRadius = 4;            // 回退用：算不出可视范围时中
 constexpr int kMaxTilesPerSide = 13;  // 单边瓦片上限(防倾斜时可视范围过大拉爆请求)
 constexpr int kBaseZoom = 13;         // 远处粗底层级(单块~4.9km)
 constexpr int kBaseRadius = 3;        // 粗底半径 ±3 → 7x7 覆盖~34km，填到天边
+constexpr int kMaxConcurrent = 8;     // 瓦片请求最大并发(防暴发饱和单域名连接)
 constexpr int kMinZoom = 3;
 constexpr int kMaxZoom = 18;
 constexpr double kGroundZ = 0.0;      // 底图置于 z=0 地面参考（剖面深度向下为负，落其下）
@@ -132,6 +134,26 @@ void TileBasemap::onInteractionEnd(vtkObject*, unsigned long, void* clientData,
     if (auto* self = static_cast<TileBasemap*>(clientData)) self->refresh();
 }
 
+void TileBasemap::enqueueGet(const QString& url, std::function<void(QNetworkReply*)> onDone) {
+    netQueue_.push_back({url, std::move(onDone)});
+    pumpNetQueue();
+}
+
+void TileBasemap::pumpNetQueue() {
+    while (netInFlight_ < kMaxConcurrent && !netQueue_.empty()) {
+        const PendingGet req = std::move(netQueue_.front());
+        netQueue_.pop_front();
+        ++netInFlight_;
+        QNetworkReply* reply = nam_.get(QNetworkRequest(QUrl(req.url)));
+        auto cb = req.cb;
+        connect(reply, &QNetworkReply::finished, this, [this, reply, cb]() {
+            cb(reply);  // 回调内部 deleteLater + 处理
+            --netInFlight_;
+            pumpNetQueue();
+        });
+    }
+}
+
 void TileBasemap::hide() { show(Hidden); }
 
 void TileBasemap::show(Kind kind) {
@@ -143,6 +165,7 @@ void TileBasemap::show(Kind kind) {
     baseTiles_.clear();
     baseLoaded_ = false;
     inFlight_.clear();
+    netQueue_.clear();  // 丢弃换源前排队中的请求(在途的按 gen 自然作废)
     desired_.clear();
     // demCache_/texCache_ 跨隐藏-重选保留 → 重选地图秒出，不重拉。
     haveBaseline_ = false;  // 数据可能已换位置 → 重算基准高程
@@ -152,8 +175,8 @@ void TileBasemap::show(Kind kind) {
         if (rw_) rw_->Render();
         return;
     }
-    ensureBaseLayer();  // 先铺远处粗底(填到天边)，再叠近处精细
-    refresh();
+    refresh();          // 先排近处精细(优先加载，用户最先看到)
+    ensureBaseLayer();  // 再排远处粗底(背景，排队在后)
 }
 
 bool TileBasemap::computeView(double& centerLat, double& centerLon, int& zoom) const {
@@ -334,8 +357,7 @@ void TileBasemap::fetchTile(int z, int x, int y, long long key) {
 
     const int gen = generation_;
     inFlight_.insert(key);
-    QNetworkReply* reply = nam_.get(QNetworkRequest(QUrl(url)));
-    connect(reply, &QNetworkReply::finished, this, [this, reply, key, z, x, y, gen]() {
+    enqueueGet(url, [this, key, z, x, y, gen](QNetworkReply* reply) {
         reply->deleteLater();
         // inFlight 保持到瓦片最终落地（起伏/平面），使旧层在新块就位前不被清理 → 无空白闪烁。
         QImage img;
@@ -423,8 +445,7 @@ void TileBasemap::fetchBaseTile(int z, int x, int y) {
         const QString durl =
             QStringLiteral("https://api.mapbox.com/v4/mapbox.terrain-rgb/%1/%2/%3.pngraw?access_token=%4")
                 .arg(z).arg(x).arg(y).arg(QString::fromLatin1(kMapboxToken));
-        QNetworkReply* dr = nam_.get(QNetworkRequest(QUrl(durl)));
-        connect(dr, &QNetworkReply::finished, this, [this, dr, demKey, gen, placeBase]() {
+        enqueueGet(durl, [this, demKey, gen, placeBase](QNetworkReply* dr) {
             dr->deleteLater();
             if (gen != generation_) return;
             QImage dem;
@@ -445,8 +466,7 @@ void TileBasemap::fetchBaseTile(int z, int x, int y) {
                        "&version=1.0.0&LAYER=img&tileMatrixSet=w&TileMatrix=%2&TileRow=%3"
                        "&TileCol=%4&style=default&format=tiles&tk=%5")
             .arg(sub).arg(z).arg(y).arg(x).arg(QString::fromLatin1(kTk));
-    QNetworkReply* reply = nam_.get(QNetworkRequest(QUrl(url)));
-    connect(reply, &QNetworkReply::finished, this, [this, reply, key, gen, onTex]() {
+    enqueueGet(url, [this, key, gen, onTex](QNetworkReply* reply) {
         reply->deleteLater();
         if (gen != generation_ || kind_ != Satellite) return;
         QImage img;
@@ -520,8 +540,7 @@ void TileBasemap::fetchTerrain(int z, int x, int y, long long key, vtkSmartPoint
             .arg(dy)
             .arg(QString::fromLatin1(kMapboxToken));
     const int gen = generation_;
-    QNetworkReply* reply = nam_.get(QNetworkRequest(QUrl(url)));
-    connect(reply, &QNetworkReply::finished, this, [this, reply, key, demKey, gen, place]() {
+    enqueueGet(url, [this, key, demKey, gen, place](QNetworkReply* reply) {
         reply->deleteLater();
         if (gen != generation_ || kind_ != Satellite ||
             desired_.find(key) == desired_.end() || placed_.count(key)) {

src/app/TileBasemap.hpp

@@ -4,6 +4,8 @@
 #include <QNetworkAccessManager>
 #include <QObject>
 
+#include <deque>
+#include <functional>
 #include <map>
 #include <memory>
 #include <set>
@@ -17,6 +19,7 @@ class vtkTexture;
 class vtkRenderWindow;
 class vtkInteractorObserver;
 class vtkCallbackCommand;
+class QNetworkReply;
 namespace geopro::render { class Scene; }
 namespace geopro::core { class GeoLocalFrame; }
 
@@ -55,6 +58,9 @@ private:
     vtkSmartPointer<vtkActor> buildWarped(int sz, int sx, int sy, int dz, int dx, int dy,
                                           vtkSmartPointer<vtkTexture> tex,
                                           const QImage& dem);  // DEM 位移网格 + 卫星贴图
+    void enqueueGet(const QString& url,
+                    std::function<void(QNetworkReply*)> onDone);  // 限并发取瓦片(回调内负责 deleteLater)
+    void pumpNetQueue();
     static void onInteractionEnd(vtkObject*, unsigned long, void* clientData, void*);
 
     geopro::render::Scene& scene_;
@@ -70,6 +76,9 @@ private:
     std::map<long long, vtkSmartPointer<vtkTexture>> texCache_;  // 影像纹理缓存，重选/缩放回看免重拉
     std::vector<vtkSmartPointer<vtkActor>> baseTiles_;     // 远处粗底层(持久,不随相机purge)
     bool baseLoaded_ = false;
+    struct PendingGet { QString url; std::function<void(QNetworkReply*)> cb; };
+    std::deque<PendingGet> netQueue_;                      // 限并发请求队列(防瓦片暴发饱和卡死)
+    int netInFlight_ = 0;
     double baseline_ = 0.0;                                 // 基准高程(首块中心)，地形绕 z=0 起伏
     bool haveBaseline_ = false;
     bool terrainProbed_ = false;                           // 首次 fetchTerrain 打一行诊断日志