NatNet: Class/Function Reference
This page provides function and class references of the NatNet SDK library.
The NatNetClient class (or NatNetClientML from the managed assembly) is the key object of the SDK. An instance of this client class allows an application to connect to a server application and query data. API helper functions are provided with the C++ library for a more convenient use of the SDK tools. For additional information, refer to the provided headers files (native) or reference the NatNatML.dll file (managed).
Note:
NatNet SDK is backwards compatible.
Deprecated methods from previous SDK versions are not documented on this page, and their use in new applications is discouraged. They are subject to removal in a future version of the SDK. Refer to the header files for complete descriptions.
The NatNetServer class has been deprecated for versions 3.0 and above.
Note that some parts of the managed .NET assembly may be slightly different from the native library reference provided here. Refer to the NatNetML.dll file using an object browser for detailed information.
ErrorCode
Most of the NatNet SDK functions return their operation results in an integer type representation named ErrorType, which is just an enumerator that describes operation results as the following:
NatNetClient Class
The NatNetClient class is the main component of the NatNet SDK. Using an instance of the NatNetClient class, you can establish a network connection with a server application (e.g. Motive) and query data descriptions, tracking data, and send/receive remote commands. For detailed declarations, refer to the NatNetClient.h header file included in the SDK.
Constructor and Destructor
NatNetClient::NatNetClient()
Constructor: Creates a new instance of a NatNetClient class. Defaults to multicast connection if no input is given.
NatNetClient::NatNetClient(iConnectionType)
Constructor: Creates a new instance of a NatNet Client using the specified connection protocol; either unicast or multicast.
Input: iConnectionType: (0 = Multicast, 1 = Unicast).
This approach is being deprecated. The NatNetClient class now determines the connection type through sNatNetClientConnectParams input when calling the NatNetClient::Connect method.
NatNetClient::~NatNetClient()
Destructor: Destructor
Member Methods
NatNetClient::Connect
Description
This method connects an instantiated NatNetClient object to a server application (e.g. Motive) at the inputted IP address.
Input Parameters:
Connection parameters object.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
sNatNetClientConenectParams:
Declared under the NatNetTypes.h file.
Local address. IP address of the localhost where the client application is running.
Server address. IP address where the server application is streaming to.
(Optional) Command port. Defaults to 1510.
(Optional) Data port. Defaults to 1511.
(Optional) Multicast IP address. Defaults to 239.255.42.99:1511.
NatNetClient::Disconnect
Description
Calling this method disconnects the client from the Motive server application.
Input Parameters:
None
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNetClient::SetFrameReceivedCallback
Description
This method sets a frame handler function and creates a new thread for receiving and processing each frame of capture data.
Managed Assembly: Use OnFrameReady event type to add a function delegate.
Input Parameters:
pfnDataCallback: A NatNetFrameReceivedCallback function. NatNetFrameReceivedCallback is a type of a pointer to a frame handler function which processes each incoming frame of tracking data. Format of the inputted function must agree with the following type definition:
typedef void (NATNET_CALLCONV* NatNetFrameReceivedCallback)(sFrameOfMocapData* pFrameOfData, void* pUserData);
User definable data: the Client object.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNetClient::SendMessageAndWait
Description
Sends a NatNet command to the NatNet server and waits for a response. See NatNet: Remote Requests/Commands for more details.
Input Parameters:
szRequest: NatNet command.
tries: Number of attempts to send the command. Default: 10.
timeout: Number of milliseconds to wait for a response from the server before the call times out. Default: 20.
ppServerResponse: Application defined response.
pResponseSize: Number of bytes in response
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNetClient::GetServerDescription
Description
Requests a description of the current NatNet server that a client object is connected to and saves it into an instance of sServerDescription. This call is blocked until the request is responded or times out.
Input Parameters:
Declared sServerDescription object.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNetClient::GetDataDescriptionList
Description
Requests a list of dataset descriptions of the capture session and saves onto the declared instance of sDataDescriptions.
Input Parameters:
Pointer to an sDataDescriptions pointer which receives the address of the client's internal sDataDescriptions object. This pointer is valid until the client is destroyed or until the next call to GetDataDescriptions.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNetClient::SecondsSinceHostTimestamp
Description
This method calculates and returns the time difference between a specific event in the processing pipeline and when the NatNet client application receives the tracking data. For example, if sFrameOfMocapData::CameraMideExposureTimestamp is inputted, it will return the latency from the camera exposure to when the tracking data is received. For more information on how it is used, read through the Latency Measurements page.
Input Parameters:
(uint64_t) A timestamp value from a sFrameOfMocapData struct.
Returns:
(double) The time, in seconds, past since the provided timestamp.
NatNet C++ API Functions
Once the NatNetSDK library has been imported into a client application, the following helper functions can be used.
These functions are available ONLY for C++ applications.
Function list
NatNet_GetVersion
Description
This function gets the version (#.#.#.#) of the NatNet SDK and saves it into an array.
Input Parameters:
Unsigned char array with a array length of 4.
Returns:
Void
NatNet_SetLogCallback
Description
This function assignes a callback handler function for receiving and reporting error/debug messages.
Input Parameters:
pfnLogCallback: NatNetLogCallback function. NatNetLogCallback is a type of a pointer to a callback function that is used to handle the log messages sent from the server application. Format of the linked function must agree with the following type definition:
typedef void (NATNET_CALLCONV* NatNetLogCallback)(Verbosity level, const char* message);
Returns:
Void
NatNet_DecodeID
Description
Takes an ID of a data set (a marker, a Rigid Body, a Skeleton, or a force plate), and decodes its model ID and member ID into the provided integer variables. For example, ID of a Skeleton bone segment will be decoded into its model ID (Skeleton) and Rigid Body ID (bone). See NatNet: Data Types.
Input Parameters:
An ID value for a respective data set (sRigidBodyData, sSkeletonData, sMarker, or sFrocePLateData) from a sFrameOfMocapData packet.
Pointer to declared integer value for saving the entity ID and the member ID (e.g. Skeleton ID and its bone Rigid Body ID).
Returns:
Void
NatNet_DecodeTimecode
Description
Helper function to decode OptiTrack timecode data into individual components.
Input Parameters:
Timecode integer from a packet of sFrameOfMocapData. (timecode)
TimecodeSubframe integer from a packet of sFrameOfMocapData. (timecodeSubframe)
Pointers to declared integer variables for saving the hours (pOutHour), minutes (pOutMinute), seconds (pOutSecond), frames (pOutFrame), and subframes (pOutSubframe) values.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_TimecodeStringify
Description
Helper function to parse OptiTrack timecode into a user friendly string in the form hh:mm:ss:ff:yy
Input Parameters:
timecode: Timecode integer from a packet of sFrameOfMocapData. (timecode)
timecodeSubframe: TimecodeSubframe integer from a packet of sFrameOfMocapData. (timecodeSubframe)
outBuffer: Declared char for saving the output.
outBufferSize: size of the character array buffer (outBuffer).
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_CopyFrame
Description
This helper function performs a deep copy of frame data from pSrc into pDst. Some members of pDst will be dynamically allocated; use NatNet_FreeFrame( pDst ) to clean them up.
Input Parameters:
Pointer to two sFrameOfMocapData variables to copy from (pSrc) and copy to (pDst).
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_FreeFrame
Description
Frees the dynamically allocated members of a frame copy created using NatNet_CopyFrame function. Note that the object pointed to by pFrame itself is NOT de-allocated, but only its nested members which were dynamically allocated are freed.
Input Parameters:
sFrameOfMocapData that has been copied using the NatNet_CopyFrame function.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
Do not call this on any pFrame data that was not the destination of a call to NatNet_CopyFrame.
NatNet_FreeDescriptions
Description
Deallocates data descriptions pDesc and all of its members; after this call, this object is no longer valid.
Input Parameters:
Data descriptions (sDataDescriptions).
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_BroadcastServerDiscovery
Description
Sends broadcast messages to discover active NatNet servers and blocks for a specified time to gather responses.
Input Parameters:
outServers: An array of length equal to the input value of pInOutNumServers. This array will receive the details of all servers discovered by the broadcast.
pInOutNumServers: A pointer to an integer containing the length of the array. After this function returns, the integer is modified to contain the total number of servers that responded to the broadcast inquiry. If the modified number is larger than the original number passed to the function, there was insufficient space for those additional servers.
timeoutMillisec: Amount of time, in milliseconds, to wait for server responses to the broadcast before returning.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_CreateAsyncServerDiscovery
Description
Begin sending periodic broadcast messages to discover active NatNet servers in the background.
Input Parameters:
pOutDiscovery: Out pointer that will receive a handle representing the asynchronous discovery process. The handle returned should be passed to NatNet_FreeAsyncServerDiscovery method later for clean up.
pfnCallback: A NatNetServerDiscoveryCallback function pointer that will be invoked once for every new server that's discovered by the asynchronous search. The callback will also be passed onto the provided pUserContext argument.
pUserContext: User-specified context data to be passed to the provided pfnCallback when invoked.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
NatNet_FreeAsyncServerDiscovery
Description
Begin sending periodic broadcast messages to continuously search and discover active NatNet servers in the background.
Input Parameters:
pOutDiscovery: Out pointer that will receive a handle representing the asynchronous discovery process. The handle returned should be passed to NatNet_FreeAsyncServerDiscovery method later for clean up.
pfnCallback: A NatNetServerDiscoveryCallback function pointer that will be invoked once for every new server that's discovered by the asynchronous search. The callback will also be passed onto the provided pUserContext argument.
pUserContext: User-specified context data to be passed to the provided pfnCallback when invoked.
Returns:
ErrorCode, On success, it returns 0 or ErrorCode_OK.
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