初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumGeometry/OctreeAvailability.h

@@ -0,0 +1,173 @@
+#pragma once
+
+#include "Availability.h"
+#include "Library.h"
+#include "OctreeTileID.h"
+#include "TileAvailabilityFlags.h"
+
+#include <cstddef>
+#include <memory>
+#include <span>
+#include <vector>
+
+namespace CesiumGeometry {
+
+/**
+ * @brief An availability tree for an octree, where availability can be stored
+ * and computed based on \ref OctreeTileID.
+ */
+class CESIUMGEOMETRY_API OctreeAvailability final {
+public:
+  /**
+   * @brief Constructs a new instance.
+   *
+   * @param subtreeLevels The number of levels in each subtree.
+   * @param maximumLevel The index of the maximum level in this tileset.
+   */
+  OctreeAvailability(uint32_t subtreeLevels, uint32_t maximumLevel) noexcept;
+
+  /**
+   * @brief Determines the currently known availability status of the given
+   * tile.
+   *
+   * @param tileID The {@link CesiumGeometry::OctreeTileID} for the tile.
+   *
+   * @return The {@link TileAvailabilityFlags} for this tile encoded into a
+   * uint8_t.
+   */
+  uint8_t computeAvailability(const OctreeTileID& tileID) const noexcept;
+
+  /**
+   * @brief Attempts to add an availability subtree into the existing overall
+   * availability tree.
+   *
+   * @param tileID The {@link CesiumGeometry::OctreeTileID} for the tile.
+   * @param newSubtree The {@link CesiumGeometry::AvailabilitySubtree} to add.
+   *
+   * @return Whether the insertion was successful.
+   */
+  bool addSubtree(
+      const OctreeTileID& tileID,
+      AvailabilitySubtree&& newSubtree) noexcept;
+
+  /**
+   * @brief Determines the currently known availability status of the given
+   * tile.
+   *
+   * Priming with a known parent subtree node avoids the need to traverse the
+   * entire availability tree so far. The node must have a loaded subtree
+   *
+   * @param tileID The tile ID to get the availability for.
+   * @param pNode The subtree node to look for the tileID in. The tileID should
+   * be within this subtree node.
+   *
+   * @return The {@link TileAvailabilityFlags} for this tile encoded into a
+   * uint8_t.
+   */
+  uint8_t computeAvailability(
+      const OctreeTileID& tileID,
+      const AvailabilityNode* pNode) const noexcept;
+
+  /**
+   * @brief Attempts to add a child subtree node onto the given parent node.
+   *
+   * Priming with a known parent subtree node avoids the need to traverse the
+   * entire availability tree so far. If the parent node is nullptr and the
+   * tile ID indicates this is the root tile, the subtree will be attached to
+   * the root.
+   *
+   * @param tileID The root tile's ID of the subtree we are trying to add.
+   * @param pParentNode The parent subtree node. The tileID should fall exactly
+   * at the end of this parent subtree.
+   *
+   * @return The newly created node if the insertion was successful, nullptr
+   * otherwise.
+   */
+  AvailabilityNode*
+  addNode(const OctreeTileID& tileID, AvailabilityNode* pParentNode) noexcept;
+
+  /**
+   * @brief Attempts to add a loaded subtree onto the given node.
+   *
+   * The node must have been created earlier from a call to addNode.
+   *
+   * @param pNode The node on which to add the subtree.
+   * @param newSubtree The new subtree to add.
+   *
+   * @return Whether the insertion was successful.
+   */
+  bool addLoadedSubtree(
+      AvailabilityNode* pNode,
+      AvailabilitySubtree&& newSubtree) noexcept;
+  /**
+   * @brief Find the child node index corresponding to this tile ID and parent
+   * node.
+   *
+   * Attempts to find the child node for the tile with the given ID and parent
+   * node. The parent node is used to speed up the search significantly. Note
+   * that if the given tile ID does not correspond exactly to an immediate
+   * child node of the parent node, nullptr will be returned. If a tileID
+   * outside the given parent node's subtree is given, an incorrect child index
+   * may be returned.
+   *
+   * @param tileID The tile ID of the child node we are looking for.
+   * @param pParentNode The immediate parent to the child node we are looking
+   * for.
+   * @return The child node index if found, std::nullopt otherwise.
+   */
+  std::optional<uint32_t> findChildNodeIndex(
+      const OctreeTileID& tileID,
+      const AvailabilityNode* pParentNode) const;
+
+  /**
+   * @brief Find the child node corresponding to this tile ID and parent node.
+   *
+   * Attempts to find the child node for the tile with the given ID and parent
+   * node. The parent node is used to speed up the search significantly. Note
+   * that if the given tile ID does not correspond exactly to an immediate
+   * child node of the parent node, nullptr will be returned. If a tileID
+   * outside the given parent node's subtree is given, an incorrect child index
+   * may be returned.
+   *
+   * @param tileID The tile ID of the child node we are looking for.
+   * @param pParentNode The immediate parent to the child node we are looking
+   * for.
+   * @return The child node if found, nullptr otherwise.
+   */
+  AvailabilityNode* findChildNode(
+      const OctreeTileID& tileID,
+      AvailabilityNode* pParentNode) const;
+
+  /**
+   * @brief Gets the number of levels in each subtree.
+   *
+   * @returns The number of levels in each subtree.
+   */
+  constexpr inline uint32_t getSubtreeLevels() const noexcept {
+    return this->_subtreeLevels;
+  }
+
+  /**
+   * @brief Gets the index of the maximum level in this implicit tileset.
+   *
+   * @returns The index of the maximum level.
+   */
+  constexpr inline uint32_t getMaximumLevel() const noexcept {
+    return this->_maximumLevel;
+  }
+
+  /**
+   * @brief Gets a pointer to the root subtree node of this implicit tileset.
+   *
+   * @returns The root node of the availability tree.
+   */
+  AvailabilityNode* getRootNode() noexcept { return this->_pRoot.get(); }
+
+private:
+  uint32_t _subtreeLevels;
+  uint32_t _maximumLevel;
+  uint32_t _maximumChildrenSubtrees;
+  std::unique_ptr<AvailabilityNode> _pRoot;
+};
+
+} // namespace CesiumGeometry