src/app/TileBasemap.cpp

@@ -39,7 +39,8 @@ namespace geopro::app {
 namespace {
 // 天地图 WMTS 令牌（与轨迹图 trajectory_map.html 同源）。
 const char* kTk = "aca91d8c9f59a4f779f39061b8a07737";
-constexpr int kRadius = 4;            // 中心瓦片 ±4 → 最多 9x9=81 块，留旋转/平移余量(治近距旋转黑边)
+constexpr int kRadius = 4;            // 回退用：算不出可视范围时中心 ±4
+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 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）
@@ -137,8 +138,8 @@ void TileBasemap::show(Kind kind) {
     for (auto& kv : placed_) scene_.renderer()->RemoveViewProp(kv.second);
     placed_.clear();
     inFlight_.clear();
-    demCache_.clear();
     desired_.clear();
+    // demCache_/texCache_ 跨隐藏-重选保留 → 重选地图秒出，不重拉。
     terrainProbed_ = false;
     kind_ = kind;
     if (kind == Hidden) {
@@ -177,6 +178,47 @@ bool TileBasemap::computeView(double& centerLat, double& centerLon, int& zoom) c
     return true;
 }
 
+bool TileBasemap::visibleGroundBox(double& west, double& south, double& east, double& north) const {
+    auto* ren = scene_.renderer();
+    if (!ren) return false;
+    const int* sz = ren->GetSize();
+    if (!sz || sz[0] <= 0 || sz[1] <= 0) return false;
+    const double W = sz[0], H = sz[1];
+    const double corners[4][2] = {{0, 0}, {W, 0}, {0, H}, {W, H}};
+
+    double minX = 1e30, minY = 1e30, maxX = -1e30, maxY = -1e30;
+    int valid = 0;
+    for (auto& c : corners) {
+        double nearP[4], farP[4];
+        ren->SetDisplayPoint(c[0], c[1], 0.0);
+        ren->DisplayToWorld();
+        ren->GetWorldPoint(nearP);
+        ren->SetDisplayPoint(c[0], c[1], 1.0);
+        ren->DisplayToWorld();
+        ren->GetWorldPoint(farP);
+        if (nearP[3] == 0.0 || farP[3] == 0.0) continue;
+        for (int k = 0; k < 3; ++k) {
+            nearP[k] /= nearP[3];
+            farP[k] /= farP[3];
+        }
+        const double dz = farP[2] - nearP[2];
+        if (std::abs(dz) < 1e-9) continue;
+        const double t = (kGroundZ - nearP[2]) / dz;  // 射线交 z=0 地面
+        if (t < 0.0 || t > 1.5) continue;             // 该角看向地平线之外/反向 → 跳过
+        const double gx = nearP[0] + t * (farP[0] - nearP[0]);
+        const double gy = nearP[1] + t * (farP[1] - nearP[1]);
+        minX = std::min(minX, gx); maxX = std::max(maxX, gx);
+        minY = std::min(minY, gy); maxY = std::max(maxY, gy);
+        ++valid;
+    }
+    if (valid < 2) return false;  // 看不到地面(地平线视角) → 让调用方回退
+
+    const auto sw = frame_->toLatLon(minX, minY);  // 局部米 → 经纬
+    const auto ne = frame_->toLatLon(maxX, maxY);
+    west = sw.lon; south = sw.lat; east = ne.lon; north = ne.lat;
+    return true;
+}
+
 void TileBasemap::refresh() {
     if (kind_ == Hidden || refreshing_) return;
     refreshing_ = true;
@@ -188,16 +230,39 @@ void TileBasemap::refresh() {
         return;
     }
 
-    const geopro::render::TileXY center = geopro::render::lonLatToTile(clon, clat, zoom);
     const int n = 1 << zoom;
+    const geopro::render::TileXY center = geopro::render::lonLatToTile(clon, clat, zoom);
+    int x0 = center.x - kRadius, x1 = center.x + kRadius;
+    int y0 = center.y - kRadius, y1 = center.y + kRadius;
+
+    // 优先按相机可视范围覆盖（治倾斜/旋转黑边）；算不出则用上面的中心±半径回退。
+    double w, s, e, nn;
+    if (visibleGroundBox(w, s, e, nn)) {
+        const geopro::render::TileXY tnw = geopro::render::lonLatToTile(w, nn, zoom);  // 西北
+        const geopro::render::TileXY tse = geopro::render::lonLatToTile(e, s, zoom);   // 东南
+        x0 = std::min(tnw.x, tse.x) - 1;  // 各留 1 圈余量
+        x1 = std::max(tnw.x, tse.x) + 1;
+        y0 = std::min(tnw.y, tse.y) - 1;
+        y1 = std::max(tnw.y, tse.y) + 1;
+        // 上限保护：单边超 kMaxTilesPerSide 则以中心截断（倾斜看地平线时范围会爆）。
+        if (x1 - x0 + 1 > kMaxTilesPerSide) {
+            const int cx = (x0 + x1) / 2;
+            x0 = cx - kMaxTilesPerSide / 2;
+            x1 = cx + kMaxTilesPerSide / 2;
+        }
+        if (y1 - y0 + 1 > kMaxTilesPerSide) {
+            const int cy = (y0 + y1) / 2;
+            y0 = cy - kMaxTilesPerSide / 2;
+            y1 = cy + kMaxTilesPerSide / 2;
+        }
+    }
+
     desired_.clear();
-    for (int dy = -kRadius; dy <= kRadius; ++dy) {
+    for (int ty = y0; ty <= y1; ++ty)
-        for (int dx = -kRadius; dx <= kRadius; ++dx) {
+        for (int tx = x0; tx <= x1; ++tx) {
-            const int tx = center.x + dx, ty = center.y + dy;
             if (tx < 0 || ty < 0 || tx >= n || ty >= n) continue;
             desired_.insert(tileKey(zoom, tx, ty));
         }
-    }
 
     // 拉取缺失瓦片（旧层暂不删，留作回退；新层落地后由 purgeStale 清理）。
     for (long long key : desired_) {
@@ -230,6 +295,22 @@ void TileBasemap::purgeStale() {
 }
 
 void TileBasemap::fetchTile(int z, int x, int y, long long key) {
+    // 命中影像缓存 → 不走网络，直接落地（DEM 多半也已缓存）。重选地图/缩放回看即秒出。
+    auto cit = texCache_.find(key);
+    if (cit != texCache_.end()) {
+        inFlight_.insert(key);
+        auto tex = cit->second;
+        if (kind_ == Satellite) {
+            fetchTerrain(z, x, y, key, tex);
+        } else {
+            placeActor(key, buildFlat(z, x, y, tex));
+            inFlight_.erase(key);
+            purgeStale();
+            if (rw_) rw_->Render();
+        }
+        return;
+    }
+
     const QString layerDir = (kind_ == Satellite) ? QStringLiteral("img_w") : QStringLiteral("vec_w");
     const QString layer = (kind_ == Satellite) ? QStringLiteral("img") : QStringLiteral("vec");
     const int sub = (x + y) % 8;  // 子域负载分担 t0-t7
@@ -262,6 +343,8 @@ void TileBasemap::fetchTile(int z, int x, int y, long long key) {
             return;
         }
         auto tex = makeTexture(img);
+        if (texCache_.size() > 1200) texCache_.clear();  // 兜底内存；在用纹理由 actor 自身保活
+        texCache_[key] = tex;                            // 缓存供重选/缩放回看复用
         if (kind_ == Satellite) {
             fetchTerrain(z, x, y, key, tex);  // 拉 DEM 后直接落地起伏块(inFlight 续到那时)
         } else {

src/app/TileBasemap.hpp

@@ -40,6 +40,8 @@ private:
     void ensureObserver();  // 首次显示时挂到交互样式的 EndInteractionEvent
     void purgeStale();      // 本轮请求全部落地后再删旧层瓦片，避免缩放空白闪烁
     bool computeView(double& centerLat, double& centerLon, int& zoom) const;
+    // 相机视锥 ∩ z=0 地面 → 可视经纬范围(治倾斜/旋转黑边)；算不出(看向地平线)返回 false。
+    bool visibleGroundBox(double& west, double& south, double& east, double& north) const;
     void fetchTile(int z, int x, int y, long long key);
     void fetchTerrain(int z, int x, int y, long long key,
                       vtkSmartPointer<vtkTexture> tex);  // 拉覆盖该瓦片的 DEM(z>15 取祖先块)后落地
@@ -60,7 +62,8 @@ private:
     std::map<long long, vtkSmartPointer<vtkActor>> placed_;  // 已贴瓦片：key→actor
     std::set<long long> desired_;                           // 当前视野应显示的瓦片 key
     std::set<long long> inFlight_;                          // 在途瓦片(续到起伏/平面最终落地)
-    std::map<long long, QImage> demCache_;                  // DEM 块缓存(key=DEMz/x/y)，避免重复拉
+    std::map<long long, QImage> demCache_;                  // DEM 块缓存(key=DEMz/x/y)，跨隐藏/重选复用
+    std::map<long long, vtkSmartPointer<vtkTexture>> texCache_;  // 影像纹理缓存，重选/缩放回看免重拉
     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