初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumGeospatial/S2CellID.h

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+#pragma once
+
+#include "Cartographic.h"
+#include "GlobeRectangle.h"
+#include "Library.h"
+
+#include <array>
+#include <cstdint>
+#include <string>
+#include <string_view>
+
+namespace CesiumGeometry {
+struct QuadtreeTileID;
+}
+
+namespace CesiumGeospatial {
+
+/**
+ * @brief A 64-bit unsigned integer that uniquely identifies a
+ * cell in the S2 cell decomposition.
+ *
+ * It has the following format:
+ *
+ *   id = [face][face_pos]
+ *
+ *   face:     a 3-bit number (range 0..5) encoding the cube face.
+ *
+ *   face_pos: a 61-bit number encoding the position of the center of this
+ *             cell along the Hilbert curve over this face (see the Wiki
+ *             pages for details).
+ *
+ * Sequentially increasing cell ids follow a continuous space-filling curve
+ * over the entire sphere.  They have the following properties:
+ *
+ *  - The id of a cell at level k consists of a 3-bit face number followed
+ *    by k bit pairs that recursively select one of the four children of
+ *    each cell.  The next bit is always 1, and all other bits are 0.
+ *    Therefore, the level of a cell is determined by the position of its
+ *    lowest-numbered bit that is turned on (for a cell at level k, this
+ *    position is 2 * (kMaxLevel - k).)
+ *
+ *  - The id of a parent cell is at the midpoint of the range of ids spanned
+ *    by its children (or by its descendants at any level).
+ *
+ * This class is adapted from S2CellId in https://github.com/google/s2geometry.
+ */
+class CESIUMGEOSPATIAL_API S2CellID {
+public:
+  /**
+   * Creates a new S2Cell from a token. A token is a hexadecimal representation
+   * of the 64-bit S2CellID.
+   *
+   * @param token The token for the S2 Cell.
+   * @returns A new S2CellID.
+   */
+  static S2CellID fromToken(const std::string_view& token);
+
+  /**
+   * @brief Creates a cell given its face (range 0..5), level, and Hilbert curve
+   * cell index within that face and level.
+   *
+   * @param face The face index.
+   * @param level The level within the face.
+   * @param position The Hilbert-order index of the cell within the face and
+   * level.
+   * @return The cell.
+   */
+  static S2CellID
+  fromFaceLevelPosition(uint8_t face, uint32_t level, uint64_t position);
+
+  /**
+   * @brief Create an S2 id from a face and a quadtree tile id.
+   *
+   * @param face The S2 face (0...5) that this tile is on.
+   * @param quadtreeTileID The quadtree tile id for this tile, within the given
+   * face.
+   */
+  static S2CellID fromQuadtreeTileID(
+      uint8_t face,
+      const CesiumGeometry::QuadtreeTileID& quadtreeTileID);
+
+  /**
+   * @brief Constructs a new S2 cell ID.
+   *
+   * The cell ID value is not validated. Use {@link isValid} to check the
+   * validity after constructions.
+   *
+   * @param id The 64-bit cell ID value.
+   */
+  S2CellID(uint64_t id);
+
+  /**
+   * @brief Determines if this cell ID is valid.
+   *
+   * @return true if the the cell ID refers to a valid cell; otherwise, false.
+   */
+  bool isValid() const;
+
+  /**
+   * @brief Gets the ID of the cell.
+   *
+   * @return The ID.
+   */
+  uint64_t getID() const { return this->_id; }
+
+  /**
+   * @brief Converts the cell ID to a hexadecimal token.
+   */
+  std::string toToken() const;
+
+  /**
+   * @brief Gets the level of the cell from the cell ID.
+   *
+   * @return The cell ID, where 0 is the root.
+   */
+  int32_t getLevel() const;
+
+  /**
+   * @brief Gets the face id (0...5) for this S2 cell.
+   */
+  uint8_t getFace() const;
+
+  /**
+   * @brief Gets the longitude/latitude position at the center of this cell.
+   *
+   * The height is always 0.0.
+   *
+   * @return The center.
+   */
+  Cartographic getCenter() const;
+
+  /**
+   * @brief Gets the vertices at the corners of the cell.
+   *
+   * The height values are always 0.0.
+   *
+   * Note that all positions inside the S2 Cell are _not_ guaranteed to fall
+   * inside the rectangle formed by these vertices.
+   *
+   * @return Four vertices specifying the corners of this cell.
+   */
+  std::array<Cartographic, 4> getVertices() const;
+
+  /**
+   * @brief Gets the parent cell of this cell.
+   *
+   * If this is a root cell, the behavior is unspecified.
+   */
+  S2CellID getParent() const;
+
+  /**
+   * @brief Gets a child cell of this cell.
+   *
+   * If the index is less than 0 or greater than 3, or if this is a leaf cell,
+   * the behavior is unspecified.
+   *
+   * @param index The index in the range 0 to 3.
+   * @return The child cell.
+   */
+  S2CellID getChild(size_t index) const;
+
+  /**
+   * @brief Computes the globe rectangle that bounds this cell.
+   *
+   * @return The globe rectangle.
+   */
+  GlobeRectangle computeBoundingRectangle() const;
+
+private:
+  uint64_t _id;
+};
+
+} // namespace CesiumGeospatial