SoLDMDataAccess Class Reference
[Misc]

Volume data access methods. More...

#include <LDM/SoLDMDataAccess.h>

List of all members.

Classes
struct	CopyInfo
struct	DataInfo
	Information about returned data when directly accessing the data rather than copying the data. More...
struct	DataInfoBox
	Information about data returned for an arbitrary box (subvolume). More...
struct	DataInfoLine
	Information about data returned for an arbitrary line. More...
struct	DataInfoPlane
	Information about data returned for an arbitrary plane. More...
class	DataInfoPolyLine
	Information about data returned for an arbitrary polyline. More...
struct	DataInfoTrace
	Information about data returned for an arbitrary trace (column of voxels). More...
Public Types
enum	ErrorValue {   CORRECT,   INCORRECT_RESOLUTION,   INCORRECT_SUBVOLUME,   INCORRECT_LINE,   INCORRECT_POLYLINE,   INCORRECT_PLANE,   INCORRECT_POSITION,   INCORRECT_COORDINATE,   MEMORY_FULL,   REQUEST_NOT_COMPLETED,   REQUEST_NOT_FOUND,   INCORRECT_BUFFER }
enum	GetDataMode {   CACHE,   DIRECT,   DIRECT_AND_PREFETCH }
Public Member Functions
	SoLDMDataAccess ()
virtual	~SoLDMDataAccess ()
void	setDataSet (SoDataSet *v)
SoDataSet *	getDataSet ()
DataInfoBox	getData (int resolution, const SbBox3i32 &subVolume0, SoBufferObject *bufferObj=NULL)
DataInfoPlane	getData (int resolution, const SbBox3i32 &subVolume0, const SbPlane &plane, SoBufferObject *bufferObj=NULL)
DataInfoLine	getData (int resolution, const SbBox3i32 &subVolume0, const SbLine &line, SoBufferObject *bufferObj=NULL)
DataInfoTrace	getData (int resolution, const SbBox3i32 &subVolume, const SbVec2i32 coord, SoBufferObject *bufferObj=NULL)
void	getData (DataInfoPolyLine &infoPolyline, int resolution, const SbBox3i32 &subVolume, int numPoints, const SbVec3i32 *polyline, SoBufferObject *bufferObj=NULL)
DataInfo	getData (int resolution, const SbVec3i32 &dataPosition)
void	releaseData (SoLDMTileID tileID)
SbBool	isTileUniform (int resolution, const SbVec3i32 &dataPosition, double &uniformValue)
int	requestData (int resolution, const SbBox3i32 &box, SoBufferObject *bufferObj)
void	getRequestedData (int requestId, DataInfoBox &infoBox)
int	requestData (int resolution, const SbBox3i32 &subVolume, const SbPlane &plane, SoBufferObject *bufferObj)
void	getRequestedData (int requestId, DataInfoPlane &infoPlane)
int	requestData (int resolution, const SbBox3i32 &subVolume0, const SbLine &line, SoBufferObject *bufferObj)
void	getRequestedData (int requestId, DataInfoLine &infoLine)
int	requestData (int resolution, const SbBox3i32 &subVolume, int numPoints, const SbVec3i32 *polyline, SoBufferObject *bufferObj)
void	getRequestedData (int requestId, DataInfoPolyLine &infoPolyline)
int	requestData (int resolution, const SbBox3i32 &subVolume0, const SbVec2i32 &coord, SoBufferObject *bufferObj)
void	getRequestedData (int requestId, DataInfoTrace &infoTrace)
virtual void	endRequest (int requestId)
SbVec3f	voxelToXYZ (const SbVec3i32 &dataPosition)
SbVec3i32	XYZToVoxel (const SbVec3f &dataPosition)
bool	setGetDataMode (const GetDataMode getDataMode)
GetDataMode	getGetDataMode ()
Deprecated
SoDEPRECATED DataInfoBox	getData (int resolution, const SbBox3i32 &subVolume, void *buffer)
SoDEPRECATED DataInfoPlane	getData (int resolution, const SbBox3i32 &subVolume, const SbPlane &plane, void *buffer)
SoDEPRECATED DataInfoLine	getData (int resolution, const SbBox3i32 &subVolume, const SbLine &line, void *buffer)
SoDEPRECATED DataInfoTrace	getData (int resolution, const SbBox3i32 &subVolume, const SbVec2i32 coord, void *buffer)
SoDEPRECATED void	getData (DataInfoPolyLine &infoPolyline, int resolution, const SbBox3i32 &subVolume, int numPoints, const SbVec3i32 *polyline, void *buffer)
SoDEPRECATED int	requestData (int resolution, const SbBox3i32 &subVolume, void *buffer)
SoDEPRECATED int	requestData (int resolution, const SbBox3i32 &subVolume, const SbPlane &plane, void *buffer)
SoDEPRECATED int	requestData (int resolution, const SbBox3i32 &subVolume, const SbLine &line, void *buffer)
SoDEPRECATED int	requestData (int resolution, const SbBox3i32 &subVolume, int numPoints, const SbVec3i32 *polyline, void *buffer)
SoDEPRECATED int	requestData (int resolution, const SbBox3i32 &subVolume, const SbVec2i32 &coord, void *buffer)

---

Detailed Description

Volume data access methods.

The Data Access API provides methods to conveniently extract data from a volume. This is useful, for example, to extract data for computation, for segmentation or for display using other primitives. The data is accessible whether the SoVolumeData is part of a scene graph or not. These methods are only valid in LDM mode (which is the default mode). The Data Access API automatically takes advantage of LDM multi-threaded data loading when multiple tiles (not already in cache) are needed to complete the request.

The Data Access API automatically loads all data required to satisfy the request and can be invoked asynchronously to allow simultaneous loading and computation. The application can request data at any resolution level, e.g. full resolution (level 0) data, independent of the resolution level currently being used for rendering. For some requests, e.g. line and plane, the application can also specify a subvolume (region of interest) that limits the extent of the data request.

SoLDMDataAccess provides the following data requests:

• Subvolume: The set of voxels inside a specified subvolume.
• Plane: The set of voxels intersecting an arbitrary plane.
• Line: The set of voxels intersecting an arbitrary line.
• Trace: A column of axis aligned voxels (e.g. a seismic trace).
• Polyline: The set of voxels intersecting an arbitrary polyline.
• Tile: Direct access to the tile containing a specified voxel. (This is the best way to query individual voxels. See the method for more information.)

Each data request returns an information struct specific to the request type. For example, SoLDMDataAccess::DataInfoBox is returned by the subvolume request. All these structs contain an errorFlag member containing the result of the request and a bufferSize member containing the amount of data (in bytes) returned. The application should always check these values. Note that even when errorFlag is CORRECT, bufferSize may be zero, meaning no data was returned. This happens, for example, if the specified plane is completely outside the volume.

The application is responsible for allocating and freeing the memory to store the requested data. Calling the data request method with a null bufferObject will return the size of the memory needed, in bytes, in the bufferSize member of the information struct. Once the buffer is allocated, a second call will extract the data from the volume. Since Open Inventor 8.0 we recommend using the methods that return data into an SoBufferObject. Because this class abstracts access to data stored on different devices it is possible, for example, to conveniently fetch data into CPU memory or directly into CUDA or OpenCL memory.

Each data request can be either synchronous or asynchronous. Synchronous means that all the data will be loaded before the function returns. Asynchronous means that the function will return immediately and you will be notified when the data is actually available. This allows the application to continue to work while the data is being loaded, for example to overlap data loading and computation. Synchronous access is done using the getData methods.

To do asynchronous access, you must create a new class derived from SoLDMDataAccess and implement your own version of the endRequest method. Begin a request by calling the appropriate requestData method. This method will return a requestId.

• If the requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the appropriate getRequestedData method to complete the transaction.
• If the requestID is negative, the data is already in memory. In this case endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method. The data inside the destBuffer will be aligned as in the original volume. The info structure contains additional information about the current request including error status, coordinates (for line and polyline requests), tile id (for tile requests), etc.

Three different modes are available to control how data is requested from the volume reader when the necessary tiles are not already present in LDM cache memory:

• CACHE: When data is requested, the data is copied from the LDM cache (tiles in memory) if possible. If any required tiles are not in the LDM cache, LDM will load those tiles into cache, then copy the data from the cache. This is the default behavior.

• DIRECT: When data is requested, the data is copied from the LDM cache (tiles in memory) if possible. If any required tiles are not in the LDM cache, LDM will request the data directly from the volume reader without loading any tiles into the LDM cache memory. This could potentially be slower than the previous mode, but uses less I/O and less memory. It allows getting data without loading the whole tile into memory, for example when the requested data is a slice.

• DIRECT_AND_PREFETCH: This mode is a mix of the previous modes. When data is requested, the data is copied from the LDM cache if possible. If any required tiles are not in the LDM cache, LDM will request the data directly from the volume reader to avoid reading complete tiles immediately, but will also schedule the relevant tiles to be loaded into the LDM cache memory asynchronously. This may improve performance overall if the application is likely to load additional data from these tiles.

Note that DIRECT access requires that specific methods are implemented in the data set reader, for example readXSliceInTile (see SoLDMReader and SoVolumeReader). The default LDM reader implements these methods for the standard Open Inventor LDM file format. Custom LDM readers may need to be enhanced.

EXAMPLE

The following example shows how to extract a subvolume from a given volume.

     // Create a volume data object and attach to a data file
     SoVolumeData* volData = new SoVolumeData();
     volData->fileName = "<path-to-filename>";

     // Call to get size of data
     int      resolution = 0; // Full resolution data
     SbBox3i32 subvolume = SbBox3i32(0,0,0,63,63,63);
     SoLDMDataAccess& access = volData->getLdmDataAccess();
     SoLDMDataAccess::DataInfoBox info = access.getData( resolution, subvolume );

     if (info.errorFlag == SoLDMDataAccess::CORRECT) {
       // Create and size a buffer to store the data
       SoRef<SoCpuBufferObject> buffer = new SoCpuBufferObject;
       buffer->setSize( info.bufferSize );

       // Call to get the actual data
       info = access.getData( resolution, subvolume, buffer.ptr() );

       // Access the data then unmap the buffer
       unsigned int* pData = (unsigned int*)buffer->map(SoBufferObject::READ_ONLY);
       unsigned int value = pData[0];
       . . .
       buffer->unmap();
     }

See $OIVHOME/examples/source/VolumeViz/examples/getLDMData/asyncGetDataBox.cxx for a more complete example.

See related examples:

MedicalComputeHistogram, MedicalGetDataBox, MedicalGetDataBox_MultiThread, MedicalGetDataLine, MedicalGetDataPlane, MedicalGetDataPolyLine, ComputeHistogram, GetDataLine, GetDataPolyLine, GetDataPlane, GetDataBox, AsyncGetDataBox, GetDataBox_multiThread, GetDataTrace, VolumeDataEditing

---

Member Enumeration Documentation

enum SoLDMDataAccess::ErrorValue

Error Code values.

Enumerator:

CORRECT	Request was successfully completed.
INCORRECT_RESOLUTION	The specified resolution is lower than the lowest resolution level of the data.
INCORRECT_SUBVOLUME	The specified subvolume does not intersect the data volume.
INCORRECT_LINE	The specified line does not intersect the specified subvolume.
INCORRECT_POLYLINE	The specified polyline does not intersect the specified subvolume.
INCORRECT_PLANE	The specified plane does not intersect the specified subvolume.
INCORRECT_POSITION	The specified position is outside the specified subvolume.
INCORRECT_COORDINATE	The trace at the specified coordinate does not intersect the specified subvolume.
MEMORY_FULL	No more memory is available.
REQUEST_NOT_COMPLETED	Requesting data from an unfinished asynchronous request.
REQUEST_NOT_FOUND	Request is unknown.
INCORRECT_BUFFER	Application buffer to copy data into is invalid. Most common cases are : buffer size does not take in account the datasize request size parameter is inclusive and app forget to remove (1,1,1) to it.

enum SoLDMDataAccess::GetDataMode

Specifies the way data is requested from the volume reader when the necessary tiles are not already present in LDM cache memory.

See the class description for more info. See setGetDataMode() method.

Enumerator:

CACHE	Request data by tile (default).
DIRECT	Request data directly. This means to only request, for example, the specific slice of data, not the complete tiles.
DIRECT_AND_PREFETCH	Same as Direct, but also schedule the relevant tiles to be loaded for faster future access.

---

Constructor & Destructor Documentation

SoLDMDataAccess::SoLDMDataAccess

(

)

Constructor.


Application must call the setDataSet method before using any other methods of this object.

virtual SoLDMDataAccess::~SoLDMDataAccess

(

)

[virtual]

Destructor.

---

Member Function Documentation

void SoLDMDataAccess::endRequest

(

int

requestId

)

[inline, virtual]

This method is called each time a data request is finished, meaning that the data requested asynchronously is now available.

This method should be overloaded in a derived class in order to handle loaded data.

SoDEPRECATED void SoLDMDataAccess::getData	(	DataInfoPolyLine &	infoPolyline,
		int	resolution,
		const SbBox3i32 &	subVolume,
		int	numPoints,
		const SbVec3i32 *	polyline,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use getData(int, const SbBox3i32&, const SbVec2i32, SoBufferObject* ) instead.

SoDEPRECATED DataInfoTrace SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbVec2i32	coord,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use getData(int, const SbBox3i32&, const SbVec2i32, SoBufferObject*) instead.

SoDEPRECATED DataInfoLine SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbLine &	line,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use getData(int, const SbBox3i32&, const SbLine&, SoBufferObject* ) instead.

SoDEPRECATED DataInfoPlane SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbPlane &	plane,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use getData(int, const SbBox3i32&, const SbPlane&, SoBufferObject*) instead.

SoDEPRECATED DataInfoBox SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use getData(int, const SbBox3i32& , SoBufferObject*) instead.

DataInfo SoLDMDataAccess::getData	(	int	resolution,
		const SbVec3i32 &	dataPosition
	)

Returns a pointer to the block of data (LDM tile) which contains the voxel at dataPosition.

The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). In most cases you will pass 0 to request full resolution data.

The data is not copied. The pointer is valid until releaseData() is called with the corresponding tile id or until the associated volumeData node is destroyed.

The LDM tile is locked in CPU memory until releaseData() is called. The application may lock multiple tiles in memory using this method. However these locked tiles count against the maximum CPU memory allowed for the volume. Locking too many tiles may reduce the rendered image quality because LDM does not have enough memory to load other tiles. A released tile will remain in memory (allowing quick re-access) for some period of time, depending on whether it is needed for rendering and (if not) on the value of SoLDMResourceParameters::tileHalfLife.

This method is a good solution when the application needs to get the values of multiple voxels that are not part of a line, plane or box. After locking a tile, for each subsequent voxel, check if the voxel position is contained in the currently locked tile. You can use the intersect() method on the SbBox3i32 tilePosition member of the DataInfo struct for this test. If the voxel is in the current tile, compute the offset into the data buffer and get its value. If not, release the current tile (using releaseData) and get the appropriate tile by calling getData() again.

 // Compute the address of a voxel value in a tile.
 // We know the position of the desired voxel in absolute IJK coords and we
 // know the location of the tile in absolute IJK coords, so we can compute
 // the voxel position relative to the tile.  But note that tiles on a "face"
 // of the volume are normally partial tiles, so we have to consider both the
 // min and max corners of the tile.
 SbVec3i32 voxelPos; // Absolute IJK position of desired voxel
 DataInfo  dataInfo; // Tile info returned by getData() method

 SbVec3i32 tileSize = dataInfo.tileDimension;
 SbVec3i32 tilePosMin, tilePosMax;
 dataInfo.tilePosition.getBounds( tilePosMin, tilePosMax );

 SbVec3i32 relPos; // Relative IJK position of desired voxel
 relPos[0] = (voxelPos[0] - tilePosMin[0]) * tileSize[0] / (tilePosMax[0] - tilePosMin[0] + 1);
 relPos[1] = (voxelPos[1] - tilePosMin[1]) * tileSize[1] / (tilePosMax[1] - tilePosMin[1] + 1);
 relPos[2] = (voxelPos[2] - tilePosMin[2]) * tileSize[2] / (tilePosMax[2] - tilePosMin[2] + 1);

 // Offset into tile data. First in voxels, then in bytes.
 int64_t offset = (relPos[2]*tileSize[1] + relPos[1])*tileSize[0] + relPos[0];
 offset *= volumeData->getDatumSize();

 // Address of voxel value
 unsigned char* voxelPtr = ((unsigned char *)dataInfo.tileData) + offset;

void SoLDMDataAccess::getData	(	DataInfoPolyLine &	infoPolyline,
		int	resolution,
		const SbBox3i32 &	subVolume,
		int	numPoints,
		const SbVec3i32 *	polyline,
		SoBufferObject *	bufferObj = NULL
	)

Given a subvolume in voxel coordinates and a polyline (set of connected line segments), copies the data intersecting each line segment with the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...) NOTE: The data is copied.

All information is returned in the struct DataInfoPolyline. Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoLine).



DataInfoTrace SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbVec2i32	coord,
		SoBufferObject *	bufferObj = NULL
	)

Data values in a single seismic trace (a row of voxels along the volume X axis) are copied into an application buffer.


The trace is identified by a YZ voxel coordinate. The range of values returned is the intersection of the trace with the specified subvolume. The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...) NOTE: The data is copied.

Returns a DataInfoTrace struct containing errorFlag, bufferSize (number of bytes) and bufferDimension (number of values). Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoTrace).



DataInfoLine SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume0,
		const SbLine &	line,
		SoBufferObject *	bufferObj = NULL
	)

Given a subvolume in voxel coordinates and a line, copies the data intersecting the line and the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...) NOTE: The data is copied.

All information is returned in the struct DataInfoLine. Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoLine).



DataInfoPlane SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume0,
		const SbPlane &	plane,
		SoBufferObject *	bufferObj = NULL
	)

Given a subvolume in voxel coordinates and a plane, copies the data intersecting the plane and the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...) NOTE: The data is copied.

All information is returned in the struct DataInfoPlane. Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoPlane).



DataInfoBox SoLDMDataAccess::getData	(	int	resolution,
		const SbBox3i32 &	subVolume0,
		SoBufferObject *	bufferObj = NULL
	)

Given a subvolume in voxel coordinates, copies the associated data into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

All information is returned in the struct DataInfoBox. Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoBox).



SoDataSet * SoLDMDataAccess::getDataSet

(

)

[inline]

Returns the associated dataset.

SoLDMDataAccess::GetDataMode SoLDMDataAccess::getGetDataMode

(

)

[inline]

Returns the GetDataMode (see setGetDataMode).

void SoLDMDataAccess::getRequestedData	(	int	requestId,
		DataInfoTrace &	infoTrace
	)

Returns the data associated with requestID into infoTrace .

void SoLDMDataAccess::getRequestedData	(	int	requestId,
		DataInfoPolyLine &	infoPolyline
	)

Returns the data associated with requestID into infoPolyline.

void SoLDMDataAccess::getRequestedData	(	int	requestId,
		DataInfoLine &	infoLine
	)

Returns the data associated with requestID into infoLine.

void SoLDMDataAccess::getRequestedData	(	int	requestId,
		DataInfoPlane &	infoPlane
	)

Returns the data associated with requestID into infoPlane.

void SoLDMDataAccess::getRequestedData	(	int	requestId,
		DataInfoBox &	infoBox
	)

Returns the data associated with requestID into infoBox.

SbBool SoLDMDataAccess::isTileUniform	(	int	resolution,
		const SbVec3i32 &	dataPosition,
		double &	uniformValue
	)

Returns TRUE if the tile containing the data located at position dataPosition (IJK voxel coordinates) at the specified resolution is uniform (all voxels have the same value).

Returns FALSE if not or if accessing the tile failed (e.g. invalid coordinates). If TRUE then uniformValue contains the uniform value of the tile, else it is undefined.

Since Open Inventor 9.1

void SoLDMDataAccess::releaseData

(

SoLDMTileID

tileID

)

Tells VolumeViz that this block of data (returned by getData above) is no longer in use by the application.

SoDEPRECATED int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbVec2i32 &	coord,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use requestData(int, const SbBox3i32&, const SbVec2i32&, SoBufferObject*) instead.

SoDEPRECATED int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		int	numPoints,
		const SbVec3i32 *	polyline,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use requestData(int, const SbBox3i32&, const SbLine&, SoBufferObject*) instead.

SoDEPRECATED int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbLine &	line,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use requestData(int, const SbBox3i32&, const SbLine&, SoBufferObject*) instead.

SoDEPRECATED int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbPlane &	plane,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use requestData(int, const SbBox3i32&, const SbPlane&, SoBufferObject*) instead.

SoDEPRECATED int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		void *	buffer
	)

Deprecated:


Deprecated since Open Inventor 8000
No longer used. Use requestData(int, const SbBox3i32&, SoBufferObject*) instead.

int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume0,
		const SbVec2i32 &	coord,
		SoBufferObject *	bufferObj
	)

Data values in a single seismic trace (a row of voxels along the volume X axis) are asynchronously copied into an application buffer.


The trace is identified by a YZ voxel coordinate. The range of values returned is the intersection of the trace with the specified subvolume (which may be the full dimensions of the volume). The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

Returns a request ID. If requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the getRequestedData method to complete the transaction. If requestID is negative, the data is already in memory, so endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method.

Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoTrace). Limitations :

• this is not possible to perform an asynchronous data request within GLRender action
  

int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		int	numPoints,
		const SbVec3i32 *	polyline,
		SoBufferObject *	bufferObj
	)

Given a subvolume in voxel coordinates and a stack of line, asynchronously copies the data intersecting each line and the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

Returns a request ID. If requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the getRequestedData method to complete the transaction. If requestID is negative, the data is already in memory, so endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method.

Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoLine). Limitations :

• this is not possible to perform an asynchronous data request within GLRender action
  

int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume0,
		const SbLine &	line,
		SoBufferObject *	bufferObj
	)

Given a subvolume in voxel coordinates and a line, asynchronously copies the data intersecting the line and the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

Returns a request ID. If requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the getRequestedData method to complete the transaction. If requestID is negative, the data is already in memory, so endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method.

Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoLine). Limitations :

• this is not possible to perform an asynchronous data request within GLRender action
  

int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	subVolume,
		const SbPlane &	plane,
		SoBufferObject *	bufferObj
	)

Given a subvolume in voxel coordinates and a plane, asynchronously copies the data intersecting the plane and the subvolume into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

Returns a request ID. If requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the getRequestedData method to complete the transaction. If requestID is negative, the data is already in memory, so endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method.

Call this method with buffer = NULL to get the required size of the application buffer (in the bufferSize member of DataInfoPlane). Limitations :

• this is not possible to perform an asynchronous data request within GLRender action
  

int SoLDMDataAccess::requestData	(	int	resolution,
		const SbBox3i32 &	box,
		SoBufferObject *	bufferObj
	)

Given a subvolume in voxel coordinates, asynchronously copies the associated data into an application buffer.


The resolution is the power of 2 of the desired subsampling level (0:1/1, 1:1/2, 2:1/4, ...). NOTE: The data is copied.

Returns a request ID. If requestID is positive, this value will be passed to the endRequest method when the requested data is ready, and can then be used with the getRequestedData method to complete the transaction. If requestID is negative, the data is already in memory, so endRequest will not be called, and -requestID (a positive value) should be used with the getRequestedData method.

Call this method with buffer = NULL to get the required size of the application buffer.

Limitations :

• it is not currently possible to query the value of a single voxel using this method. The smallest query possible is 8 voxels (a subvolume 2 x 2 x 2).
• this is not possible to perform an asynchronous data request within GLRender action
  

void SoLDMDataAccess::setDataSet

(

SoDataSet *

v

)

Set dataset to fetch data from.

bool SoLDMDataAccess::setGetDataMode

(

const GetDataMode

getDataMode

)

Set the GetDataMode.


This controls how data is requested from the volume reader when the necessary tiles are not already present in LDM cache memory. Default is CACHE.

SbVec3f SoLDMDataAccess::voxelToXYZ

(

const SbVec3i32 &

dataPosition

)

Convert a voxel coordinate (I,J,K) to a geometry coordinate (X,Y,Z).

SbVec3i32 SoLDMDataAccess::XYZToVoxel

(

const SbVec3f &

dataPosition

)

Convert a geometry coordinate (X,Y,Z) to a voxel coordinate (I,J,K).

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The documentation for this class was generated from the following file:
• LDM/SoLDMDataAccess.h