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).

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).

NatNetClient::~NatNetClient()

Destructor: Destructor

Member Methods

NatNetClient::Connect

ErrorCode        Connect( const sNatNetClientConnectParams& connectParams );

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.

typedef struct sNatNetClientConnectParams
{
    ConnectionType connectionType;
    uint16_t serverCommandPort;
    uint16_t serverDataPort;
    const char* serverAddress;
    const char* localAddress;
    const char* multicastAddress;

#if defined(__cplusplus)
    sNatNetClientConnectParams()
        : connectionType( ConnectionType_Multicast )
        , serverCommandPort( 0 )
        , serverDataPort( 0 )
        , serverAddress( NULL )
        , localAddress( NULL )
        , multicastAddress( NULL )
    {
    }
#endif
} sNatNetClientConnectParams;

NatNetClient::Disconnect

ErrorCode        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

ErrorCode        SetFrameReceivedCallback( NatNetFrameReceivedCallback pfnDataCallback, void* pUserContext = 0 );

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

ErrorCode	SendMessageAndWait( const char* szRequest, 
                                    void** ppServerResponse, 
                                    int* pResponseSize );

ErrorCode	SendMessageAndWait( const char* szRequest,
                                    int tries, int timeout, 
                                    void** ppServerResponse,
                                    int* pResponseSize );

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

ErrorCode        GetServerDescription( sServerDescription* pServerDescription );

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

int   GetDataDescriptions( sDataDescriptions** pDataDescriptions );

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

double    SecondsSinceHostTimestamp( uint64_t hostTimestamp ) const;

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.

Function list

NatNet_GetVersion

 NATNET_API void	NATNET_CALLCONV NatNet_GetVersion( unsigned char outVersion[4] );

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

 NATNET_API void	NATNET_CALLCONV NatNet_SetLogCallback( NatNetLogCallback pfnLogCallback );

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

 NATNET_API void	NATNET_CALLCONV NatNet_DecodeID( int compositeId,
           						int* pOutEntityId,
         						int* pOutMemberId );

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

NATNET_API ErrorCode	NATNET_CALLCONV	NatNet_DecodeTimecode( 	unsigned int timecode,
           						unsigned int timecodeSubframe,
              						int* pOutHour, int* pOutMinute,
              						int* pOutSecond, int* pOutFrame,
             						int* pOutSubframe );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_TimecodeStringify( unsigned int timecode, 
              							unsigned int timecodeSubframe,
              							char* outBuffer,
              							int outBufferSize );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_CopyFrame( sFrameOfMocapData* pSrc,
              						sFrameOfMocapData* pDst );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_FreeFrame( sFrameOfMocapData* pFrame );

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.

NatNet_FreeDescriptions

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_FreeDescriptions( sDataDescriptions* pFrame );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_BroadcastServerDiscovery( sNatNetDiscoveredServer* outServers, int* pInOutNumServers, unsigned int timeoutMillisec = 1000 );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_CreateAsyncServerDiscovery( NatNetDiscoveryHandle* pOutDiscovery, NatNetServerDiscoveryCallback pfnCallback, void* pUserContext = NULL );

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

NATNET_API ErrorCode	NATNET_CALLCONV NatNet_CreateAsyncServerDiscovery( NatNetDiscoveryHandle* pOutDiscovery, NatNetServerDiscoveryCallback pfnCallback, void* pUserContext = NULL );

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.