SoVolumeTransform Class |
Transform data before texture creation.
Namespace: OIV.VolumeViz.Nodes
The SoVolumeTransform type exposes the following members.
Name | Description | |
---|---|---|
AddInCache | Add the transformed data for a specific tile to the cache. | |
AffectsState | Returns true if a node has an effect on the state during traversal. | |
Apply | Apply in-place transformation to the specified dataset tile. | |
Callback | (Overrides SoNodeCallback(SoCallbackAction).) | |
Copy | Calls Copy(false). (Inherited from SoNode.) | |
Copy(Boolean) | Creates and returns an exact copy of the node. | |
CopyFieldValues(SoFieldContainer) | Calls CopyFieldValues(fc, false). (Inherited from SoFieldContainer.) | |
CopyFieldValues(SoFieldContainer, Boolean) | Copies the contents of fc's fields into this object's fields. | |
Dispose |
Releases all resources used by SoDisposable.
(Inherited from SoDisposable.) | |
Distribute | (Inherited from SoNode.) | |
DoAction | (Overrides SoNodeDoAction(SoAction).) | |
EnableNotify | Notification at this Field Container is enabled (if flag == true) or disabled (if flag == false). | |
Equals | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) | |
FieldsAreEqual | Returns true if this object's fields are exactly equal to fc's fields. | |
Get | Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string. | |
GetAllFields | Returns a list of fields, including the eventIn's and eventOut's. | |
GetAlternateRep | This method is called by actions to allow the node to provide an "alternate representation" when appropriate (typically depending on the action type). | |
GetBoundingBox | (Inherited from SoNode.) | |
GetEventIn | Returns a the eventIn with the given name. | |
GetEventOut | Returns the eventOut with the given name. | |
GetField | Returns a the field of this object whose name is fieldName. | |
GetFieldName | Returns the name of the given field in the fieldName argument. | |
GetFields | Appends references to all of this object's fields to resultList, and returns the number of fields appended. | |
GetFromCache | Returns the previously transformed data for a specific tile. | |
GetHashCode |
Overrides GetHashCode().
(Inherited from SoNetBase.) | |
GetMatrix | (Inherited from SoNode.) | |
GetName | Returns the name of an instance. | |
GetPrimitiveCount | (Inherited from SoNode.) | |
GetRenderEngineMode | Returns the supported Render engine mode. | |
GetRenderUnitID | (Inherited from SoNode.) | |
GetStringName | (Inherited from SoBase.) | |
GetTransformedMinMax | Based on min max of the input data, this function should return the expected data range of the result (transformed) data. | |
GetType | Gets the Type of the current instance. (Inherited from Object.) | |
GLRender | (Overrides SoNodeGLRender(SoGLRenderAction).) | |
GLRenderBelowPath | (Inherited from SoNode.) | |
GLRenderInPath | (Inherited from SoNode.) | |
GLRenderOffPath | (Inherited from SoNode.) | |
GrabEventsCleanup | (Inherited from SoNode.) | |
GrabEventsSetup | (Inherited from SoNode.) | |
HandleEvent | (Inherited from SoNode.) | |
HasDefaultValues | Returns true if all of the object's fields have their default values. | |
IsBoundingBoxIgnoring | This method is used by getBoundingBox action traversal to know if the current node must be traversed or not, ie the bounding should be ignored. | |
IsNotifyEnabled | Notification is the process of telling interested objects that this object has changed. | |
IsOverride | Returns the state of the override flag. | |
IsSynchronizable | Gets the ScaleViz synchronizable state of this object. | |
IsValid | Should return true if the given parameters are valid for this compute function. | |
Pick | (Overrides SoNodePick(SoPickAction).) | |
RayPick | (Inherited from SoNode.) | |
Search | (Inherited from SoNode.) | |
Set | Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format. | |
SetName | (Inherited from SoBase.) | |
SetOverride | Turns the override flag on or off. | |
SetSynchronizable | Sets this to be a ScaleViz synchronizable object. | |
SetToDefaults | Sets all fields in this object to their default values. | |
ToString |
Converts this SoBase structure to a human readable string.
(Inherited from SoBase.) | |
Touch | Marks an instance as modified, simulating a change to it. | |
Write | (Overrides SoNodeWrite(SoWriteAction).) |
Name | Description | |
---|---|---|
cacheSize | Size of the computed tile cache for this transform. | |
IsDisposable | ISafeDisposable interface implementation.
(Inherited from SoDisposable.) | |
UserData |
Gets or sets the user data to be contained by the field container.
(Inherited from SoFieldContainer.) | |
volumeTransformId | Allows the transform to be applied to all or one specific data set. |
The OIV.VolumeViz.Nodes.SoVolumeTransform node allows an application to apply a defined computation on LDM data tiles just before they are sent to the GPU. There are several other ways to apply a computation to LDM tiles, that are applied at different stages of the pipeline. The OIV.LDM.Nodes.SoLDMDataTransform class for example (see the dataTransform field of OIV.LDM.Nodes.SoDataSet) applies a computation to each LDM tile requested from the volume reader before the tile is stored in system memory. This can be used to create multiple data sets from a single input (e.g. on disk) data set, but has the drawback that each resulting data set must be stored in system memory. OIV.VolumeViz.Nodes.SoVolumeTransform can be used to create multiple data sets from a single data set in system memory and does not require storing the created data sets in system memory (only on the GPU).
A cache mechanism, local to each instance of OIV.VolumeViz.Nodes.SoVolumeTransform, allows storing the computed tiles for later reuse. The size of this cache (number of tiles to cache) can be specified using the OIV.VolumeViz.Nodes.SoVolumeTransform.cacheSize field. We recommend setting the cacheSize to the number of tiles needed to display the biggest expected slice. As an example, for a dataset of size 128x512x1024 with a tile size equal to 128, the biggest slice size is 512x1024. So 4x8 = 32 LDM tiles are needed for rendering and therefore a cacheSize of 32 (tiles) is needed to avoid computing the same tile multiple times. The apply method can retrieve the transformed data for other tiles from the cache and can explicitly add the transformed data for other tiles to the cache.
OIV.VolumeViz.Nodes.SoVolumeTransform works on tiles (not slices or volumes). If a compute function needs data from other tiles, the application may use the OIV.LDM.SoLDMDataAccess API to get that data. (This is another difference from OIV.LDM.Nodes.SoLDMDataTransform, which does not allow using the LDM data access API.)
Multiple OIV.VolumeViz.Nodes.SoVolumeTransform nodes may be applied to the same OIV.LDM.Nodes.SoDataSet. The transforms are applied in the order of their appearance in the scene graph. OIV.VolumeViz.Nodes.SoVolumeTransform nodes may also be applied only to a specific OIV.LDM.Nodes.SoDataSet using the OIV.VolumeViz.Nodes.SoVolumeTransform.volumeTransformId field. If this field is zero (the default), the transform is applied to all subsequent data set nodes. Else the transform is only applied to data sets whose dataSetId field contains the same value as the volumeTransformId.
OIV.VolumeViz.Nodes.SoVolumeTransform is based on the Open Inventor computing framework and uses the OIV.Inventor.Devices.SoBufferObject classes to abstract and manage blocks of memory. The application can use different devices to implement the computation, and manage input tiles and output tiles stored on different devices.
As mentioned previously, OIV.VolumeViz.Nodes.SoVolumeTransform can be used to create multiple data sets on-the-fly from a single data set in system memory. In this case the same data set node will be instanced multiple times in the scene graph (although its data will only be loaded in system memory once), but we still need to assign each data texture a unique id so the shader program can access them uniquely. This is done using OIV.LDM.Nodes.SoDataSetId nodes to specify a different data set id for each instance of the data set node. If an OIV.LDM.Nodes.SoDataSetId node is in the traversal state when a data set node is traversed, the dataSetId field is ignored and the id from the OIV.LDM.Nodes.SoDataSetId node is used.
To implement a computation, the application must derive a new class from OIV.VolumeViz.Nodes.SoVolumeTransform and (at least) implement the OIV.VolumeViz.Nodes.SoVolumeTransform.Apply(OIV.Inventor.Misc.SoState, OIV.Inventor.Generic.SbPair{{OIV.LDM.Nodes.SoDataSet,System.Int32}}, OIV.Inventor.Devices.SoBufferObject, OIV.LDM.SoLDMTileID) method, which performs the actual computation. This method is called with parameters that give access to information about the data set and the specific tile being computed. In a simple case you might only need to access the buffer object.
It may also be useful to implement the OIV.VolumeViz.Nodes.SoVolumeTransform.IsValid(OIV.Inventor.Misc.SoState, OIV.Inventor.Generic.SbPair{{OIV.LDM.Nodes.SoDataSet,System.Int32}}, OIV.Inventor.Devices.SoBufferObject, OIV.LDM.SoLDMTileID) and OIV.VolumeViz.Nodes.SoVolumeTransform.GetTransformedMinMax(System.Double@, System.Double@) methods. The OIV.VolumeViz.Nodes.SoVolumeTransform.IsValid(OIV.Inventor.Misc.SoState, OIV.Inventor.Generic.SbPair{{OIV.LDM.Nodes.SoDataSet,System.Int32}}, OIV.Inventor.Devices.SoBufferObject, OIV.LDM.SoLDMTileID) method will be called for each tile immediately before the OIV.VolumeViz.Nodes.SoVolumeTransform.Apply(OIV.Inventor.Misc.SoState, OIV.Inventor.Generic.SbPair{{OIV.LDM.Nodes.SoDataSet,System.Int32}}, OIV.Inventor.Devices.SoBufferObject, OIV.LDM.SoLDMTileID) method. If this method returns false, then the OIV.VolumeViz.Nodes.SoVolumeTransform.Apply(OIV.Inventor.Misc.SoState, OIV.Inventor.Generic.SbPair{{OIV.LDM.Nodes.SoDataSet,System.Int32}}, OIV.Inventor.Devices.SoBufferObject, OIV.LDM.SoLDMTileID) method will not be called for that tile. If the application can compute or estimate the min and max values of the computed data set, then it should implement the OIV.VolumeViz.Nodes.SoVolumeTransform.GetTransformedMinMax(System.Double@, System.Double@) method so VolumeViz does not do unnecessary work to compute these values.
VolumeTransform {
volumeTransformId | 0 |
cacheSize | 1 |
OIV.Inventor.Actions.SoCallbackAction, OIV.Inventor.Actions.SoGLRenderAction Sets volume transform parameters in the traversal state.