typedef struct XrSpatialCapabilityConfigurationPlaneTrackingEXT {
    XrStructureType                     type;
    const void*                         next;
    XrSpatialCapabilityEXT              capability;
    uint32_t                            enabledComponentCount;
    const XrSpatialComponentTypeEXT*    enabledComponents;
} XrSpatialCapabilityConfigurationPlaneTrackingEXT;

typedef enum XrSpatialPlaneAlignmentEXT {
    XR_SPATIAL_PLANE_ALIGNMENT_HORIZONTAL_UPWARD_EXT = 0,
    XR_SPATIAL_PLANE_ALIGNMENT_HORIZONTAL_DOWNWARD_EXT = 1,
    XR_SPATIAL_PLANE_ALIGNMENT_VERTICAL_EXT = 2,
    XR_SPATIAL_PLANE_ALIGNMENT_ARBITRARY_EXT = 3,
    XR_SPATIAL_PLANE_ALIGNMENT_MAX_ENUM_EXT = 0x7FFFFFFF
} XrSpatialPlaneAlignmentEXT;

typedef struct XrSpatialComponentPlaneAlignmentListEXT {
    XrStructureType                type;
    void*                          next;
    uint32_t                       planeAlignmentCount;
    XrSpatialPlaneAlignmentEXT*    planeAlignments;
} XrSpatialComponentPlaneAlignmentListEXT;

typedef struct XrSpatialComponentMesh2DListEXT {
    XrStructureType          type;
    void*                    next;
    uint32_t                 meshCount;
    XrSpatialMeshDataEXT*    meshes;
} XrSpatialComponentMesh2DListEXT;

typedef struct XrSpatialPolygon2DDataEXT {
    XrPosef               origin;
    XrSpatialBufferEXT    vertexBuffer;
} XrSpatialPolygon2DDataEXT;

typedef struct XrSpatialComponentPolygon2DListEXT {
    XrStructureType               type;
    void*                         next;
    uint32_t                      polygonCount;
    XrSpatialPolygon2DDataEXT*    polygons;
} XrSpatialComponentPolygon2DListEXT;

typedef enum XrSpatialPlaneSemanticLabelEXT {
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_UNCATEGORIZED_EXT = 1,
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_FLOOR_EXT = 2,
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_WALL_EXT = 3,
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_CEILING_EXT = 4,
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_TABLE_EXT = 5,
    XR_SPATIAL_PLANE_SEMANTIC_LABEL_MAX_ENUM_EXT = 0x7FFFFFFF
} XrSpatialPlaneSemanticLabelEXT;

typedef struct XrSpatialComponentPlaneSemanticLabelListEXT {
    XrStructureType                    type;
    void*                              next;
    uint32_t                           semanticLabelCount;
    XrSpatialPlaneSemanticLabelEXT*    semanticLabels;
} XrSpatialComponentPlaneSemanticLabelListEXT;

// Check if plane tracking capability is supported
uint32_t capabilityCount;
CHK_XR(xrEnumerateSpatialCapabilitiesEXT(instance, systemId, 0, &capabilityCount, nullptr));
std::vector<XrSpatialCapabilityEXT> capabilities(capabilityCount);
CHK_XR(xrEnumerateSpatialCapabilitiesEXT(instance, systemId, capabilityCount, &capabilityCount, capabilities.data()));

if (std::find(capabilities.begin(), capabilities.end(), XR_SPATIAL_CAPABILITY_PLANE_TRACKING_EXT) == capabilities.end()) {
  return;
}

// Enumerate supported components for plane tracking capability
XrSpatialCapabilityComponentTypesEXT planeComponents{XR_TYPE_SPATIAL_CAPABILITY_COMPONENT_TYPES_EXT};
CHK_XR(xrEnumerateSpatialCapabilityComponentTypesEXT(instance, systemId, XR_SPATIAL_CAPABILITY_PLANE_TRACKING_EXT, &planeComponents));
std::vector<XrSpatialComponentTypeEXT> planeCapabilityComponents(planeComponents.componentTypeCountOutput);
planeComponents.componentTypeCapacityInput = planeCapabilityComponents.size();
planeComponents.componentTypes = planeCapabilityComponents.data();
CHK_XR(xrEnumerateSpatialCapabilityComponentTypesEXT(instance, systemId, XR_SPATIAL_CAPABILITY_PLANE_TRACKING_EXT, &planeComponents));

// Check if polygon 2D and plane semantic labels optional components are supported
const auto supportsComponent = [&planeCapabilityComponents](XrSpatialComponentTypeEXT component) {
  return std::find(planeCapabilityComponents.begin(), planeCapabilityComponents.end(), component) != planeCapabilityComponents.end();
};

const bool supportsPolygon2DComponent = supportsComponent(XR_SPATIAL_COMPONENT_TYPE_POLYGON_2D_EXT);
const bool supportsSemanticLabelComponent = supportsComponent(XR_SPATIAL_COMPONENT_TYPE_PLANE_SEMANTIC_LABEL_EXT);

// Create a spatial context
XrSpatialContextEXT spatialContext{};

// Enable the 2 guaranteed components of the plane tracking capability
std::vector<XrSpatialComponentTypeEXT> enabledComponents = {
  XR_SPATIAL_COMPONENT_TYPE_BOUNDED_2D_EXT,
  XR_SPATIAL_COMPONENT_TYPE_PLANE_ALIGNMENT_EXT,
};
// Optionally enable polygon2D if it is supported
if (supportsPolygon2DComponent) {
  enabledComponents.push_back(XR_SPATIAL_COMPONENT_TYPE_POLYGON_2D_EXT);
}
// Optionally enable semantic labels if it is supported
if (supportsSemanticLabelComponent) {
  enabledComponents.push_back(XR_SPATIAL_COMPONENT_TYPE_PLANE_SEMANTIC_LABEL_EXT);
}

XrSpatialCapabilityConfigurationPlaneTrackingEXT planeConfig{XR_TYPE_SPATIAL_CAPABILITY_CONFIGURATION_PLANE_TRACKING_EXT};
planeConfig.capability = XR_SPATIAL_CAPABILITY_PLANE_TRACKING_EXT;
planeConfig.enabledComponentCount = enabledComponents.size();
planeConfig.enabledComponents = enabledComponents.data();

std::array<XrSpatialCapabilityConfigurationBaseHeaderEXT*, 1> capabilityConfigs = {
  reinterpret_cast<XrSpatialCapabilityConfigurationBaseHeaderEXT*>(&planeConfig),
};

XrSpatialContextCreateInfoEXT spatialContextCreateInfo{XR_TYPE_SPATIAL_CONTEXT_CREATE_INFO_EXT};
spatialContextCreateInfo.capabilityConfigCount = capabilityConfigs.size();
spatialContextCreateInfo.capabilityConfigs = capabilityConfigs.data();
XrFutureEXT createContextFuture;
CHK_XR(xrCreateSpatialContextAsyncEXT(session, &spatialContextCreateInfo, &createContextFuture));

waitUntilReady(createContextFuture);

XrCreateSpatialContextCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_CONTEXT_COMPLETION_EXT};
CHK_XR(xrCreateSpatialContextCompleteEXT(session, createContextFuture, &completion));
if (completion.futureResult != XR_SUCCESS) {
  return;
}

spatialContext = completion.spatialContext;

// ...
// Discover entities with the spatial context
// ...

CHK_XR(xrDestroySpatialContextEXT(spatialContext));

XrFutureEXT future = XR_NULL_FUTURE_EXT;

// We want to look for entities that have the following components.
std::vector<XrSpatialComponentTypeEXT> snapshotComponents = {
  XR_SPATIAL_COMPONENT_TYPE_BOUNDED_2D_EXT,
  XR_SPATIAL_COMPONENT_TYPE_PLANE_ALIGNMENT_EXT,
};
if (supportsPolygon2DComponent) {
  snapshotComponents.push_back(XR_SPATIAL_COMPONENT_TYPE_POLYGON_2D_EXT);
}
if (supportsSemanticLabelComponent) {
  snapshotComponents.push_back(XR_SPATIAL_COMPONENT_TYPE_PLANE_SEMANTIC_LABEL_EXT);
}

auto discoverSpatialEntities = [&](XrSpatialContextEXT spatialContext, XrTime time) {
  XrSpatialDiscoverySnapshotCreateInfoEXT snapshotCreateInfo{XR_TYPE_SPATIAL_DISCOVERY_SNAPSHOT_CREATE_INFO_EXT};
  snapshotCreateInfo.componentTypeCount = snapshotComponents.size();
  snapshotCreateInfo.componentTypes = snapshotComponents.data();
  CHK_XR(xrCreateSpatialDiscoverySnapshotAsyncEXT(spatialContext, &snapshotCreateInfo, &future));

  waitUntilReady(future);

  XrCreateSpatialDiscoverySnapshotCompletionInfoEXT completionInfo{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_INFO_EXT};
  completionInfo.baseSpace = localSpace;
  completionInfo.time = time;
  completionInfo.future = future;

  XrCreateSpatialDiscoverySnapshotCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_EXT};
  CHK_XR(xrCreateSpatialDiscoverySnapshotCompleteEXT(spatialContext, &completionInfo, &completion));
  if (completion.futureResult == XR_SUCCESS) {

    // Query for the semantic label component data
    XrSpatialComponentDataQueryConditionEXT queryCond{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_CONDITION_EXT};
    queryCond.componentTypeCount = snapshotComponents.size();
    queryCond.componentTypes = snapshotComponents.data();

    XrSpatialComponentDataQueryResultEXT queryResult{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_RESULT_EXT};
    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    std::vector<XrSpatialEntityIdEXT> entityIds(queryResult.entityIdCountOutput);
    std::vector<XrSpatialEntityTrackingStateEXT> entityStates(queryResult.entityIdCountOutput);
    queryResult.entityIdCapacityInput = entityIds.size();
    queryResult.entityIds = entityIds.data();
    queryResult.entityStateCapacityInput = entityStates.size();
    queryResult.entityStates = entityStates.data();

    std::vector<XrSpatialBounded2DDataEXT> bounded2D(queryResult.entityIdCountOutput);
    XrSpatialComponentBounded2DListEXT bounded2DList{XR_TYPE_SPATIAL_COMPONENT_BOUNDED_2D_LIST_EXT};
    bounded2DList.boundCount = bounded2D.size();
    bounded2DList.bounds = bounded2D.data();
    queryResult.next = &bounded2DList;

    std::vector<XrSpatialPolygon2DDataEXT> polygons;
    XrSpatialComponentPolygon2DListEXT polygonList{XR_TYPE_SPATIAL_COMPONENT_POLYGON_2D_LIST_EXT};
    if (supportsPolygon2DComponent) {
      polygons.resize(queryResult.entityIdCountOutput);
      polygonList.polygonCount = polygons.size();
      polygonList.polygons = polygons.data();
      polygonList.next = queryResult.next;
      queryResult.next = &polygonList;
    }

    std::vector<XrSpatialPlaneSemanticLabelEXT> semanticLabels;
    XrSpatialComponentPlaneSemanticLabelListEXT semanticLabelsList{XR_TYPE_SPATIAL_COMPONENT_PLANE_SEMANTIC_LABEL_LIST_EXT};
    if (supportsSemanticLabelComponent) {
      semanticLabels.resize(queryResult.entityIdCountOutput);
      semanticLabelsList.semanticLabelCount = semanticLabels.size();
      semanticLabelsList.semanticLabels = semanticLabels.data();
      semanticLabelsList.next = queryResult.next;
      queryResult.next = &semanticLabelsList;
    }

    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    for (int32_t i = 0; i < queryResult.entityIdCountOutput; ++i) {
      if (entityStates[i] != XR_SPATIAL_ENTITY_TRACKING_STATE_TRACKING_EXT) {
        continue;
      }

      // 2D bounds for entity entityIds[i] is bounded2D[i].extents centered on bounded2D[i].center.

      if (supportsPolygon2DComponent) {
        // 2D polygon for entity entityIds[i] is the buffer represented by polygons[i].bufferId.
        // Application uses flink:xrGetSpatialBufferVector2fEXT to get the buffer data.
      }

      if (supportsSemanticLabelComponent) {
        // semantic label for entity entityIds[i] is semanticLabels[i].
      }
    }

    CHK_XR(xrDestroySpatialSnapshotEXT(completion.snapshot));
  }
};

while (1) {
  // ...
  // For every frame in frame loop
  // ...

  XrFrameState frameState;  // previously returned from xrWaitFrame
  const XrTime time = frameState.predictedDisplayTime;

  // Poll for the XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT event
  XrEventDataBuffer event = {XR_TYPE_EVENT_DATA_BUFFER};
  XrResult result = xrPollEvent(instance, &event);
  if (result == XR_SUCCESS) {
      switch (event.type) {
          case XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT: {
              const XrEventDataSpatialDiscoveryRecommendedEXT& eventdata =
                  *reinterpret_cast<XrEventDataSpatialDiscoveryRecommendedEXT*>(&event);
              // Discover spatial entities for the context that we received the "discovery
              // recommended" event for.
              discoverSpatialEntities(eventdata.spatialContext, time);
              break;
          }
      }
  }

  // ...
  // Finish frame loop
  // ...
}