OpenNI 1.5.4: Global Error State

The Error State capability allows a node implementation to notify OpenNI that it is in an error state, meaning it cannot function properly. An application can check each node's error state separately, but most of the times the application only needs to know if any one of the nodes is in an error state, and does not really care which one or how many (except for user notification purposes).

OpenNI aggregates the error state of all the nodes together into a single error state, the Global Error State, making it easier for the application to find out about current state. When the Global Error State is XN_STATUS_OK this means all the nodes are OK. If only one node is in an error state, that error state will also become the global error state (for example, if one sensor is disconnected, the OpenNI global error state will be XN_STATUS_DEVICE_NOT_CONNECTED). If more than one node is in an error state, the global error state will be XN_STATUS_MULTIPLE_NODES_ERROR. In such a case, if needed, the application can search all the nodes in the production graph and check which of them are in an error state and why.