Add gltf converting for vctr

Cesium3DTilesContent/include/Cesium3DTilesContent/VctrToGltfConverter.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include "GltfConverterResult.h"
+
+#include <Cesium3DTilesContent/GltfConverters.h> // Include for AssetFetcher definition
+#include <CesiumAsync/Future.h>
+#include <CesiumGltf/Model.h>
+#include <CesiumGltfReader/GltfReader.h>
+
+#include <optional>
+#include <span>
+
+namespace Cesium3DTilesContent {
+
+/**
+ * @brief Converts a vctr (Vector) file to a glTF.
+ *
+ * For more information on the vctr format, see
+ * https://github.com/CesiumGS/3d-tiles/blob/main/specification/TileFormats/VectorData/README.md
+ */
+struct VctrToGltfConverter {
+  /**
+   * @brief Converts a vctr binary file to a glTF model.
+   *
+   * @param vctrBinary The bytes loaded for the vctr model.
+   * @param options Options for how the glTF should be loaded.
+   * @param assetFetcher The \ref AssetFetcher containing information used by
+   * loaded assets.
+   * @returns A future that resolves to a \ref GltfConverterResult.
+   */
+  static CesiumAsync::Future<GltfConverterResult> convert(
+      const std::span<const std::byte>& vctrBinary,
+      const CesiumGltfReader::GltfReaderOptions& options,
+      const AssetFetcher& assetFetcher);
+};
+} // namespace Cesium3DTilesContent

Cesium3DTilesContent/src/BatchTableToGltfStructuralMetadata.cpp

@@ -1,4 +1,4 @@
-#include "BatchTableToGltfStructuralMetadata.h"
+#include "BatchTableToGltfStructuralMetadata.h"
 
 #include "BatchTableHierarchyPropertyValues.h"
 #include "MetadataProperty.h"
@@ -2251,4 +2251,101 @@ ErrorList BatchTableToGltfStructuralMetadata::convertFromI3dm(
   }
   return result;
 }
+ErrorList BatchTableToGltfStructuralMetadata::convertFromVctr(
+    const rapidjson::Document& featureTableJson,
+    const rapidjson::Document& batchTableJson,
+    const std::span<const std::byte>& batchTableBinaryData,
+    CesiumGltf::Model& gltf) {
+
+  // Check to make sure a char of rapidjson is 1 byte
+  static_assert(
+      sizeof(rapidjson::Value::Ch) == 1,
+      "RapidJson::Value::Ch is not 1 byte");
+
+  ErrorList result;
+
+  // for calcuate total feature count
+  int64_t totalFeatureCount = 0;
+
+  // Check for POINTS_LENGTH
+  const auto pointsLengthIt = featureTableJson.FindMember("POINTS_LENGTH");
+  if (pointsLengthIt != featureTableJson.MemberEnd() &&
+      pointsLengthIt->value.IsInt64() && pointsLengthIt->value.GetInt64() > 0) {
+    totalFeatureCount += pointsLengthIt->value.GetInt64();
+  }
+
+  // Check for POLYLINES_LENGTH
+  const auto polylinesLengthIt =
+      featureTableJson.FindMember("POLYLINES_LENGTH");
+  if (polylinesLengthIt != featureTableJson.MemberEnd() &&
+      polylinesLengthIt->value.IsInt64() &&
+      polylinesLengthIt->value.GetInt64() > 0) {
+    totalFeatureCount += polylinesLengthIt->value.GetInt64();
+  }
+
+  // Check for POLYGONS_LENGTH
+  const auto polygonsLengthIt = featureTableJson.FindMember("POLYGONS_LENGTH");
+  if (polygonsLengthIt != featureTableJson.MemberEnd() &&
+      polygonsLengthIt->value.IsInt64() &&
+      polygonsLengthIt->value.GetInt64() > 0) {
+    totalFeatureCount += polygonsLengthIt->value.GetInt64();
+  }
+
+  // if there is no valid feature, then output a warning and return.
+  if (totalFeatureCount == 0) {
+    result.emplaceWarning(
+        "The VCTR has a batch table, but it is being ignored because there "
+        "are no valid geometry features in the feature table.");
+    return result;
+  }
+
+  // convert batch table
+  convertBatchTableToGltfStructuralMetadataExtension(
+      batchTableJson,
+      batchTableBinaryData,
+      gltf,
+      totalFeatureCount,
+      result);
+
+  // Create an EXT_mesh_features extension for each primitive with a _BATCHID
+  // attribute.
+  for (Mesh& mesh : gltf.meshes) {
+    for (MeshPrimitive& primitive : mesh.primitives) {
+      auto batchIDIt = primitive.attributes.find("_BATCHID");
+      if (batchIDIt == primitive.attributes.end()) {
+        // This primitive has no batch ID, ignore it.
+        continue;
+      }
+
+      // Rename the _BATCHID attribute to _FEATURE_ID_0
+      primitive.attributes["_FEATURE_ID_0"] = batchIDIt->second;
+      primitive.attributes.erase("_BATCHID");
+
+      // Also rename the attribute in the Draco extension, if it exists.
+      ExtensionKhrDracoMeshCompression* pDraco =
+          primitive.getExtension<ExtensionKhrDracoMeshCompression>();
+      if (pDraco) {
+        auto dracoIt = pDraco->attributes.find("_BATCHID");
+        if (dracoIt != pDraco->attributes.end()) {
+          pDraco->attributes["_FEATURE_ID_0"] = dracoIt->second;
+          pDraco->attributes.erase("_BATCHID");
+        }
+      }
+
+      ExtensionExtMeshFeatures& extension =
+          primitive.addExtension<ExtensionExtMeshFeatures>();
+      gltf.addExtensionUsed(ExtensionExtMeshFeatures::ExtensionName);
+
+      FeatureId& featureID = extension.featureIds.emplace_back();
+
+      // Use the total feature count for VCTR
+      featureID.featureCount = totalFeatureCount;
+      featureID.attribute = 0;
+      featureID.label = "_FEATURE_ID_0";
+      featureID.propertyTable = 0;
+    }
+  }
+
+  return result;
+}
 } // namespace Cesium3DTilesContent

Cesium3DTilesContent/src/BatchTableToGltfStructuralMetadata.h

@@ -1,4 +1,4 @@
-#pragma once
+#pragma once
 
 #include <CesiumGltf/Model.h>
 #include <CesiumUtility/ErrorList.h>
@@ -28,5 +28,11 @@ struct BatchTableToGltfStructuralMetadata {
       const std::span<const std::byte>& featureTableJsonData,
       const std::span<const std::byte>& batchTableBinaryData,
       CesiumGltf::Model& gltf);
+
+  static CesiumUtility::ErrorList convertFromVctr(
+      const rapidjson::Document& featureTableJson,
+      const rapidjson::Document& batchTableJson,
+      const std::span<const std::byte>& batchTableBinaryData,
+      CesiumGltf::Model& gltf);
 };
 } // namespace Cesium3DTilesContent