初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumGltfContent/SkirtMeshMetadata.h

@@ -0,0 +1,112 @@
+#include <CesiumUtility/JsonValue.h>
+
+#include <glm/vec3.hpp>
+
+#include <optional>
+
+namespace CesiumGltfContent {
+
+/**
+ * @brief Metadata obtained from a glTF that describes the skirts present on the
+ * mesh.
+ *
+ * @remarks Skirts are a technique for hiding cracks between adjacent tiles
+ * where the geometry at the edges of tiles is extended downwards, like the
+ * edges of a tablecloth hanging off of a table. These skirts are included in
+ * the glTF when they're generated, in the case of 3D Tiles, or they are
+ * generated by Cesium Native when terrain is loaded, in the case of Quantized
+ * Mesh terrain. `SkirtMeshMetadata` is attached to the glTF to allow Cesium
+ * Native to know which parts of the mesh are original and which contain the
+ * generated skirts, for operations such as creating texture coordinates for
+ * raster overlays.
+ */
+struct SkirtMeshMetadata {
+  /**
+   * @brief Creates a new `SkirtMeshMetadata` with zeroes in all fields.
+   */
+  SkirtMeshMetadata() noexcept
+      : noSkirtIndicesBegin{0},
+        noSkirtIndicesCount{0},
+        noSkirtVerticesBegin{0},
+        noSkirtVerticesCount{0},
+        meshCenter{0.0, 0.0, 0.0},
+        skirtWestHeight{0.0},
+        skirtSouthHeight{0.0},
+        skirtEastHeight{0.0},
+        skirtNorthHeight{0.0} {}
+
+  /**
+   * @brief Parses `SkirtMeshMetadata` from the `extras` field of a glTF mesh,
+   * if present.
+   *
+   * @param extras The extras field of the glTF mesh.
+   * @returns An optional containing the `SkirtMeshMetadata` if it was present
+   * on the mesh.
+   */
+  static std::optional<SkirtMeshMetadata>
+  parseFromGltfExtras(const CesiumUtility::JsonValue::Object& extras);
+
+  /**
+   * @brief Creates a glTF mesh extras value from the provided
+   * `SkirtMeshMetadata`.
+   *
+   * This might be used when generating a glTF at runtime, in order to provide
+   * information on the mesh's skirts to the rest of Cesium Native.
+   *
+   * @param skirt The skirt to create the glTF extras object from.
+   * @returns An object representing the value of a glTF extras field containing
+   * the skirt metadata.
+   */
+  static CesiumUtility::JsonValue::Object
+  createGltfExtras(const SkirtMeshMetadata& skirt);
+
+  /**
+   * @brief The start index of the range of a glTF mesh's indices buffer that
+   * should \b NOT be considered part of the skirt.
+   */
+  uint32_t noSkirtIndicesBegin;
+  /**
+   * @brief The length of the range of a glTF mesh's indices buffer that should
+   * \b NOT be considered part of the skirt.
+   *
+   * Any indices outside of the range `(noSkirtIndicesBegin,
+   * noSkirtIndicesBegin + noSkirtIndicesCount)` will be considered part of the
+   * skirt.
+   */
+  uint32_t noSkirtIndicesCount;
+  /**
+   * @brief The start index of the range of a glTF mesh's vertices buffer that
+   * should \b NOT be considered part of the skirt.
+   */
+  uint32_t noSkirtVerticesBegin;
+  /**
+   * @brief The length of the range of a glTF mesh's vertices buffer that should
+   * \b NOT be considered part of the skirt.
+   *
+   * Any vertices outside of the range `(noSkirtVerticesBegin,
+   * noSkirtVerticesBegin + noSkirtVerticesCount)` will be considered part of
+   * the skirt.
+   */
+  uint32_t noSkirtVerticesCount;
+  /**
+   * @brief The center coordinates of the mesh, in \ref glossary-ecef.
+   */
+  glm::dvec3 meshCenter;
+  /**
+   * @brief The height of the skirt on the western edge of the mesh.
+   */
+  double skirtWestHeight;
+  /**
+   * @brief The height of the skirt on the southern edge of the mesh.
+   */
+  double skirtSouthHeight;
+  /**
+   * @brief The height of the skirt on the eastern edge of the mesh.
+   */
+  double skirtEastHeight;
+  /**
+   * @brief The height of the skirt on the northern edge of the mesh.
+   */
+  double skirtNorthHeight;
+};
+} // namespace CesiumGltfContent