feat: Sprint 8 收尾 — KD-Tree/OcTree ray query + mesh QEM 完善

include/vde/spatial/kd_tree.h

@@ -1,10 +1,13 @@
 #pragma once
 #include "vde/spatial/spatial_index.h"
+#include <vector>
 
 namespace vde::spatial {
 using core::AABB3D;
 using core::Point3D;
+using core::Vector3D;
 using core::Ray3Dd;
+using core::Triangle3D;
 
 template <typename T>
 class KDTree : public SpatialIndex<T> {
@@ -17,8 +20,34 @@ public:
     std::vector<T> query_ray(const Ray3Dd& ray) const override;
     void clear() override;
     size_t size() const override { return items_.size(); }
+
 private:
+    struct Node {
+        AABB3D bounds;
+        int item_idx = -1;   // -1 for internal node; index into items_ for leaf
+        int split_axis = 0;
+        int left = -1;
+        int right = -1;
+    };
+
     std::vector<T> items_;
+    std::vector<Node> nodes_;
+    int root_ = -1;
+
+    /// Return a representative 3D position for the item (used for spatial ordering)
+    static Point3D get_position(const T& item);
+
+    /// Return an axis-aligned bounding box for the item
+    static AABB3D get_aabb(const T& item);
+
+    /// Test whether the item intersects a ray
+    static bool ray_hits_item(const T& item, const Ray3Dd& ray);
+
+    int build_recursive(int start, int end);
+    void query_range_recursive(int node_idx, const AABB3D& range,
+                               std::vector<T>& result) const;
+    void query_ray_recursive(int node_idx, const Ray3Dd& ray,
+                             std::vector<T>& result) const;
 };
 
 }  // namespace vde::spatial

include/vde/spatial/octree.h

@@ -24,10 +24,18 @@ public:
     std::vector<T> query_ray(const Ray3Dd& ray) const override;
     void clear() override;
     size_t size() const override;
+
 private:
     void insert_recursive(int node_idx, const T& item, int depth);
     void subdivide_recursive(int node_idx, int depth);
-    void query_range_recursive(int node_idx, const AABB3D& range, std::vector<T>& result) const;
+    void query_range_recursive(int node_idx, const AABB3D& range,
+                               std::vector<T>& result) const;
+    void query_ray_recursive(int node_idx, const Ray3Dd& ray,
+                             std::vector<T>& result) const;
+
+    /// Item position helper (for non-Point3D types)
+    static Point3D get_position(const T& item);
+
     std::shared_ptr<OctreeData<T>> data_;
     int max_depth_, max_items_;
 };