SoVolumeBufferedShape Class Reference

Buffered shape node for volume data. More...

#include <VolumeViz/nodes/SoVolumeBufferedShape.h>

Inheritance diagram for SoVolumeBufferedShape:

Public Member Functions
virtual SoType	getTypeId () const
	Returns the type identifier for this specific instance.
	SoVolumeBufferedShape ()
	Constructor.
Public Member Functions inherited from SoBufferedShape
	SoBufferedShape ()
	Default constructor.
Public Member Functions inherited from SoShape
virtual SbBool	affectsState () const
	Overrides default method on SoNode.
ShapeType	getShapeType ()
	Gets the current shape Full Scene Antialiasing type.
Public Member Functions inherited from SoNode
virtual void	setOverride (const SbBool state)
	Turns the override flag on or off.
virtual SbBool	isOverride () const
	Returns the state of the override flag.
virtual SoNode *	copy (SbBool copyConnections=FALSE) const
	Creates and returns an exact copy of the node.
virtual void	touch ()
	Marks an instance as modified, simulating a change to it.
Public Member Functions inherited from SoFieldContainer
void	setToDefaults ()
	Sets all fields in this object to their default values.
SbBool	hasDefaultValues () const
	Returns TRUE if all of the object's fields have their default values.
SbBool	fieldsAreEqual (const SoFieldContainer *fc) const
	Returns TRUE if this object's fields are exactly equal to fc's fields.
void	copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE)
	Copies the contents of fc's fields into this object's fields.
SoNONUNICODE SbBool	set (const char *fieldDataString)
	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.
SbBool	set (const SbString &fieldDataString)
	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.
void	get (SbString &fieldDataString)
	Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.
virtual int	getFields (SoFieldList &list) const
	Appends references to all of this object's fields to resultList, and returns the number of fields appended.
virtual int	getAllFields (SoFieldList &list) const
	Returns a list of fields, including the eventIn's and eventOut's.
virtual SoField *	getField (const SbName &fieldName) const
	Returns a the field of this object whose name is fieldName.
virtual SoField *	getEventIn (const SbName &fieldName) const
	Returns a the eventIn with the given name.
virtual SoField *	getEventOut (const SbName &fieldName) const
	Returns the eventOut with the given name.
SbBool	getFieldName (const SoField *field, SbName &fieldName) const
	Returns the name of the given field in the fieldName argument.
SbBool	enableNotify (SbBool flag)
	Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE).
SbBool	isNotifyEnabled () const
	Notification is the process of telling interested objects that this object has changed.
virtual void	setUserData (void *data)
	Sets application data.
void *	getUserData (void) const
	Gets user application data.
Public Member Functions inherited from SoBase
virtual SbName	getName () const
	Returns the name of an instance.
virtual void	setName (const SbName &name)
	Sets the name of an instance.
void	setSynchronizable (const bool b)
	Sets this to be a ScaleViz synchronizable object.
bool	isSynchronizable () const
	Gets the ScaleViz synchronizable state of this object.
Public Member Functions inherited from SoRefCounter
void	ref () const
	Adds a reference to an instance.
void	unref () const
	Removes a reference from an instance.
void	unrefNoDelete () const
	unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.
int	getRefCount () const
	Returns current reference count.
void	lock () const
	lock this instance.
void	unlock () const
	unlock this instance.
Public Member Functions inherited from SoTypedObject
SbBool	isOfType (const SoType &type) const
	Returns TRUE if this object is of the type specified in type or is derived from that type.
template<typename TypedObjectClass >
SbBool	isOfType () const
	Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class.
Public Member Functions inherited from SoVolumeGeometry
	SoVolumeGeometry ()
	Constructor.
virtual	~SoVolumeGeometry ()
	Destructor.
virtual void	setRenderProgress (SoProgressIndicator *ps)
	Set an application defined SoProgressIndicator object which will raise an event before and after the rendering task, before and after each subtask (in this case: Texture creation and Geometry creation) and after each step in the subtasks which represents in most cases individual tiles of data.

Static Public Member Functions
static SoType	getClassTypeId ()
	Returns the type identifier for this class.
Static Public Member Functions inherited from SoBufferedShape
static SoType	getClassTypeId ()
	Returns the type identifier for this class.
Static Public Member Functions inherited from SoShape
static SoType	getClassTypeId ()
	Returns the type identifier for this class.
static SbBool	isPrimitiveRestartAvailable (SoState *state=NULL)
	Returns TRUE if the primitive restart feature is available.
Static Public Member Functions inherited from SoNode
static SoType	getClassTypeId ()
	Returns the type identifier for this class.
static SoNode *	getByName (const SbName &name)
	A node's name can be set using SoBase::setName().
static int	getByName (const SbName &name, SoNodeList &list)
	A node's name can be set using SoBase::setName().
Static Public Member Functions inherited from SoFieldContainer
static SoType	getClassTypeId ()
	Returns the type of this class.
Static Public Member Functions inherited from SoBase
static SoType	getClassTypeId ()
	Returns type identifier for this class.
Static Public Member Functions inherited from SoTypedObject
static SoType	getClassTypeId ()
	Returns the type identifier for this class.

Public Attributes
SoSFBool	clipGeometry
	Specifies to clip the geometry at the volume boundaries.
SoSFFloat	offset
	Sets an offset value used for computing the texture coordinates.
SoSFEnum	interpolation
	Interpolation mode.
Public Attributes inherited from SoBufferedShape
SoSFEnum	shapeUsage
	Defines the usage of the shape.
SoSFBool	primitiveRestartEnabled
	Enable/disable the primitive restart feature.
SoSFInt32	primitiveRestartValue
	Index value for the primitive restart feature.
SoSFBool	useNormalsGenerator
	Indicates if the node should use the internal normal vector generator if no normals are defined.
SoSFEnum	shapeType
	Shape type to render.
SoMFInt32	numVertices
	Total number of vertices/indices or number of vertices/indices to be used per primitive.
SoSFBufferObject	vertexBuffer
	Buffer object that contains the vertex data.
SoSFShort	vertexComponentsCount
	Number of components in each vertex.
SoSFEnum	vertexComponentsType
	SbDataType::DataType for vertices.
SoSFShort	vertexStride
	Stride in bytes between the first component of two consecutive vertices.
SoSFInt32	vertexOffset
	Offset in bytes to the first vertex within the buffer.
SoSFBufferObject	normalBuffer
	Buffer object that contains the (optional) normal vectors.
SoSFEnum	normalComponentsType
	SbDataType::DataType type for the normal vectors.
SoSFShort	normalStride
	Stride in bytes between the first component of two consecutive normals.
SoSFInt32	normalOffset
	Offset in bytes to the first normal vector in the buffer.
SoSFBufferObject	indexBuffer
	Buffer object that contains the (optional) indices.
SoSFEnum	indexType
	SbDataType::DataType type for the indices.
SoSFInt32	indexOffset
	Offset in bytes to the first index in the buffer.
SoSFBufferObject	colorBuffer
	Buffer object that contains the (optional) color values.
SoSFEnum	colorComponentsType
	SbDataType::DataType type for the color values.
SoSFInt32	colorStride
	Stride in bytes between the first component of two consecutive colors.
SoSFInt32	colorOffset
	Offset in bytes to the first color value in the buffer.
SoSFInt32	colorComponentsCount
	Number of components in each color value.
SoMFBufferObject	texCoordsBuffer
	Buffer objects that contains the (optional) texture coordinates.
SoMFEnum	texCoordsComponentsType
	SbDataType::DataType type for the texture coordinates.
SoMFInt32	texCoordsStride
	Stride in bytes between the first component of two consecutive texture coordinates.
SoMFInt32	texCoordsOffset
	Offset in bytes to the first texture coordinate in the buffer.
SoMFInt32	texCoordsComponentsCount
	Number of components in each texture coordinate.
Public Attributes inherited from SoShape
SoSFBool	boundingBoxIgnoring
	Whether to ignore this node during bounding box traversal.

Additional Inherited Members
Public Types inherited from SoBufferedShape
enum	Type {   POINTS ,   LINE_STRIP ,   LINE_LOOP ,   LINES ,   TRIANGLE_STRIP ,   TRIANGLE_FAN ,   TRIANGLES ,   QUAD_STRIP ,   QUADS ,   POLYGON }
	Type of shape that will be rendered. More...
enum	Usage {   STATIC ,   DYNAMIC }
	This enum is used to set the shapeUsage field. More...
Public Types inherited from SoShape
enum	ShapeType {   POINTS ,   LINES ,   POLYGONS ,   TEXT }
	Basic type for antialiased rendering for this shape (Do not consider the SoDrawStyle property currently in the state). More...

Detailed Description

Buffered shape node for volume data.

This node defines a shape which is the intersection of the volume data defined by an SoVolumeData node and the 3D shape defined by an SoBufferedShape node. The shape defined by this intersection is colored using the data values from the current SoVolumeData node and color map from the current SoTransferFunction node.

The shape defined by this intersection is textured using the data from the current SoVolumeData node and SoTransferFunction node. The interpolation field controls how the texture is interpolated. Texture coordinates are automatically computed for each vertex based on its position relative to the 3D extent of the volume. If texture coordinates are specified, they are ignored.

This node can be used to create custom "slices" through the volume, for example a cylinder slice. It can be considered a generalization of the SoOrthoSlice, SoObliqueSlice, SoFenceSlice, etc features. But note:

• Compared to an equivalent standard slice (e.g. SoOrthoSlice), the rendering may be slightly different due to positioning and interpolation.
• The standard slices (e.g. SoOrthoSlice) have "two-sided lighting" enabled by default as a convenience. This is not true for volume geometry nodes (which have the same default as their corresponding standard geometry node), so the "back" side of the geometry will not be lighted unless you enable two-sided lighting using an SoShapeHints node.

When set to FALSE, the clipGeometry field allows rendering of the portion of the geometry that does not intersect the volume data. This portion is not textured and is rendered as a regular SoBufferedShape.

This node uses 3D texturing and is not available if the hardware does not support this feature.

SoBufferedShape provides fields for:

• Vertices
• Indices (optional)
• Colors (optional)
• Normals (optional)
• Texture coordinates (optional)

SoVolumeBufferedShape is useful to manage the rendering of large geometry, provide application control over where the data is stored (CPU or GPU) and to integrate rendering with the Open Inventor computing framework (through the SoBufferObject classes).

SoVolumeBufferedShape can render many types of geometric primitives including points, lines, quads and triangles. (A single type must be specified per instance of SoVolumeBufferedShape.) You specify the type of primitive in the SoSFEnum field shapeType.

SoVolumeBufferedShape can render multiple primitives of the same type. You can specify the number of vertices (or indices if provided) to use for each primitive in the SoMFInt32 field numVertices (similar to SoFaceSet).

You can also use the primitive restart feature to define multiple indexed strip shapes, for example TRIANGLE_STRIP or LINE_STRIP. The end of each primitive is marked by a special index value in the index buffer and this value can be specified in the primitiveRestartValue field. The behavior is similar to the "-1" value that can be used in Open Inventor indexed shape nodes like SoIndexedFaceSet, but is implemented on the GPU.

NOTE:

• Primitive restart must be explicitly enabled using the primitiveRestartEnabled field.
• Check availability of primitive restart using SoShape::isPrimitiveRestartAvailable().

The geometry and its attributes must be stored in buffer objects (see SoBufferObject). The buffer objects can be SoGLBufferObjects stored directly on the graphics board or SoCpuBufferObjects stored in system memory. This allows the application to control what data is stored where.

If lighting is enabled (there is no SoLightModel node or the model field of the SoLightModel is set to PHONG) and the normalBuffer field is not set, then normal vectors are automatically generated, similar to other geometry nodes. Normal generation is affected by the creaseAngle field of the SoShapeHints node if the vertices are NOT indexed. If the vertices are indexed the creaseAngle is forced to PI in order to have smooth surface rendering. It is not possible to display sharp edges by using indexed vertices if the normals are not set by the application. It is possible to disable normal generation (if for example the normals are generated by a geometry shader) by setting the useNormalsGenerator field to FALSE. Note that normal generation is disabled in some cases. See the limitations section. If no normal vectors are specified or generated, and lighting is enabled, the primitive may not be rendered correctly.

SoVolumeBufferedShape provides fields to describe the content of each buffer, e.g. the data type and number of components in each buffer, as well as how to access the buffers, e.g. the offset into the buffer and "stride" separating data values in the buffer. The default values for offset and stride assume that the vertices, normals, etc are each in a separate buffer. However setting appropriate offset and stride allows, for example, vertices and normals to be interleaved in a single buffer. In this case the same buffer would be set into both the vertexBuffer and normalBuffer fields.

To disable computing the bounding box, which can take a long time with very large geometry, use the SoBBox node to specify a pre-computed bounding box.

Limitations

• Projections:
  The projections used in the VolumeViz mechanism are not handled by SoVolumeBufferedShape.
• Lighting:
  If there is no normalBuffer the normals are generated by Inventor. The crease angle (field of SoShapeHints) is not considered by the normal generator if the vertices are indexed (crease angle is PI). So if the application wants to render sharp edges on its shape, it must use the vertexBuffer without indices in the indexBuffer.
• Transparency:
  If there is no color buffer, making the entire shape transparent using an SoMaterial node works as usual. However if there is a color buffer with RGBA values, note that Open Inventor does not currently check the color buffer for transparency (alpha values < 1). So in this case the SoVolumeBufferedShape will not be considered transparent geometry (even if there are alpha values < 1) and may not be rendered correctly. You can force Open Inventor to handle the shape as transparent geometry by putting an SoMaterial node with non-zero transparency before it in the scene graph.
• Normal generation:
  Automatic generation of normal vectors is ONLY enabled when:
  • The vertexComponentsCount field is set to 3 (default),
  • The vertexComponentsType field is set to SbDataType::FLOAT (default),
  • The primitiveRestartEnabled field is set to FALSE (default), and
  • The primitives are faces (i.e. neither points nor lines).
• SoGetPrimitiveCountAction:
  When using the primitive restart feature, the triangle/line count returned by the SoGetPrimitiveCountAction will not be accurate.
• Concave polygons:
  Unlike (for example) SoFaceSet, SoVolumeBufferedShape does not automatically tesselate concave or complex polygons. Such primitives may not be rendered correctly.
• SoWriteAction:
  SoVolumeBufferedShape can be saved to and restored from a .iv file just like any other Open Inventor node. However, during the read operation any OpenGL buffer objects (SoGLBufferObject) in the file will be created as CPU buffers (SoCpuBufferObject) if there is no OpenGL context bound during the read operation.
• Material binding (etc):
  SoVolumeBufferedShape effectively only supports per-vertex and per-vertex-indexed binding of materials, normals and texture coordinates.
• Simplification:
  SoVolumeBufferedShape is ignored by the "simplify" actions (SoShapeSimplifyAction, SoGlobalSimplifyAction, SoReorganizeAction).

Notes:

• The volume size and orientation (like geometry) can be modified by transformation nodes in the scene graph and this in turn modifies the appearance of volume rendering nodes like SoVolumeBufferedShape. However the same transformation must be applied to the volume data node and all volume rendering nodes associated with that volume. So effectively any transformation nodes that affect the volume must be placed before the volume data node.
• Composition with Multiple Data:
  It is possible to compose datasets that have different dimensions, tile sizes and transformations.
  In order to help fetch the correct data values in custom shaders, texture coordinates conversion functions are provided in the VolumeViz/vvizStructure.h shader include.
  For instance,

  vec3 VVizTextureToTextureVec(in VVizDataSetId datasetSrc, in VVizDataSetId datasetDst, in vec3 texCoord);

  can be used to convert texture coordinates related to one dataset to texture coordinates related to another dataset.
  The conversion is based solely on the transformations applied to each dataset, which are defined by their model matrix and their extent.
  Please note that the model matrix of a dataset is defined by to the SoTransformation nodes that are placed before the SoDataSet node in the order of the traversal.

FILE FORMAT/DEFAULT

VolumeBufferedShape {

clipGeometry	TRUE
offset	0
interpolation	LINEAR
useNormalsGenerator	TRUE
shapeType	TRIANGLES
numVertices	0
vertexBuffer	NULL
vertexComponentsCount	3
vertexComponentsType	SbDataType::FLOAT
vertexStride	0
vertexOffset	0
normalBuffer	NULL
normalComponentsType	SbDataType::FLOAT
normalStride	3 * sizeof(float)
normalOffset	0
indexBuffer	NULL
indexType	SbDataType::UNSIGNED_INT32
indexOffset	0
colorBuffer	NULL
colorComponentsType	SbDataType::FLOAT
colorStride	0
colorOffset	0
colorComponentsCount	3
texCoordsBuffer	NULL
texCoordsComponentsType	SbDataType::FLOAT
texCoordsStride	0
texCoordsOffset	0
texCoordsComponentsCount	2
primitiveRestartEnabled	FALSE
primitiveRestartValue	-1

}

ACTION BEHAVIOR

SoGLRenderAction
Draws primitives based on the current coordinates, normals, materials, drawing style, and so on.

SoRayPickAction
Picks primitives based on the current coordinates and transformation. Details about the intersection are returned in an SoFaceDetail.

SoGetBoundingBoxAction
Computes the bounding box that encloses all vertices of the face set with the current transformation applied to them. Sets the center to the real center of the bounding box: center{ (xmax + xmin) / 2, (ymax + ymin) / 2, (zmax + zmin) / 2 }

SoCallbackAction
If any triangle callbacks are registered with the action, they will be invoked for each successive triangle generated from each face in the set.

SEE ALSO

SoBufferedShape, SoVolumeData, SoTransferFunction, SoROI, SoVolumeIndexedFaceSet, SoVolumeIndexedTriangleStripSet, SoVolumeTriangleStripSet, SoFaceDetail

Definition at line 276 of file SoVolumeBufferedShape.h.

Constructor & Destructor Documentation

SoVolumeBufferedShape()

SoVolumeBufferedShape::SoVolumeBufferedShape

(

)

Constructor.

Member Function Documentation

getClassTypeId()

static SoType SoVolumeBufferedShape::getClassTypeId ( )

static

Returns the type identifier for this class.

getTypeId()

virtual SoType SoVolumeBufferedShape::getTypeId ( ) const

virtual

Returns the type identifier for this specific instance.

Reimplemented from SoBufferedShape.

Member Data Documentation

clipGeometry

SoSFBool SoVolumeBufferedShape::clipGeometry

Specifies to clip the geometry at the volume boundaries.

The SoROI node also affects the clipping process. Default is TRUE.

Definition at line 286 of file SoVolumeBufferedShape.h.

interpolation

SoSFEnum SoVolumeBufferedShape::interpolation

Interpolation mode.

Use enum SoVolumeShape::Interpolation. Default is LINEAR. NOTE: In most cases on modern graphics boards, indexed textures are used, so this refers to interpolation of volume data values.

Definition at line 304 of file SoVolumeBufferedShape.h.

offset

SoSFFloat SoVolumeBufferedShape::offset

Sets an offset value used for computing the texture coordinates.

The texture coordinate for each vertex will be taken from a point offset units away from the vertex. The offset is measured in the direction of the vertex normal. By default the offset is equal to 0 (no offset). When using this feature, a vertex normal must exist for every vertex. If vertex normals are not supplied, Open Inventor will compute vertex normals in the usual way except that the crease angle will be fixed at PI in order to assure that a vertex normal is computed at every vertex.

Definition at line 299 of file SoVolumeBufferedShape.h.

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The documentation for this class was generated from the following file:

• VolumeViz/nodes/SoVolumeBufferedShape.h