SoLevelOfDetail(3IV)

NAME
SoLevelOfDetail — level-of-detail switching group node

INHERITS FROM
SoBase > SoFieldContainer > SoNode > SoGroup > SoLevelOfDetail

SYNOPSIS
#include <Inventor/nodes/SoLevelOfDetail.h>

Fields from class SoLevelOfDetail:

SoMFFloat
screenArea

Methods from class SoLevelOfDetail:

SoLevelOfDetail()
static SoType
getClassTypeId()

Methods from class SoGroup:

void
addChild(SoNode *child)
void
insertChild(SoNode *child, int newChildIndex)
SoNode *
getChild(int index) const
int
findChild(const SoNode *child) const
int
getNumChildren() const
void
removeChild(int index)
void
removeChild(SoNode *child)
void
removeAllChildren()
void
replaceChild(int index, SoNode *newChild)
void
replaceChild(SoNode *oldChild, SoNode *newChild)

Methods from class SoNode:

void
setOverride(SbBool state)
SbBool
isOverride() const
SoNode *
copy(SbBool copyConnections = FALSE) const
virtual SbBool
affectsState() const
static SoNode *
getByName(const SbName &name)
static int
getByName(const SbName &name, SoNodeList &list)

Methods from class SoFieldContainer:

void
setToDefaults()
SbBool
hasDefaultValues() const
SbBool
fieldsAreEqual(const SoFieldContainer *fc) const
void
copyFieldValues(const SoFieldContainer *fc, SbBool copyConnections = FALSE)
SbBool
set(const char *fieldDataString)
void
get(SbString &fieldDataString)
virtual int
getFields(SoFieldList &resultList) const
virtual SoField *
getField(const SbName &fieldName) const
SbBool
getFieldName(const SoField *field, SbName &fieldName) const
SbBool
isNotifyEnabled() const
SbBool
enableNotify(SbBool flag)

Methods from class SoBase:

void
ref()
void
unref() const
void
unrefNoDelete() const
void
touch()
virtual SoType
getTypeId() const
SbBool
isOfType(SoType type) const
virtual void
setName(const SbName &name)
virtual SbName
getName() const

DESCRIPTION
The children of this node typically represent the same object or objects at varying levels of detail, from highest detail to lowest. The size of the objects when projected into the viewport is used to determine which version to use (i.e., which child to traverse).

The size is computed as the area of the screen rectangle enclosing the projection of the 3D bounding box that encloses all of the children. When rendering, this size is compared to the values in the screenArea field. If the size is greater than the first value, child 0 is traversed. If it is smaller than the first, but greater than the second, child 1 is traversed, and so on. If there are fewer children than are required by this rule, the last child is traversed. The screenArea field contains just 0 by default, so the first child is always traversed.

The size calculation takes the current complexity into account. If the complexity is 0 or is of type BOUNDING_BOX, the last child is always traversed. If the complexity is less than .5, the computed size is scaled down appropriately to use (possibly) a less detailed representation. If the complexity is greater than .5, the size is scaled up. At complexity 1, the first child is always used.

Note that the SoLOD node is similar to SoLevelOfDetail, except the switching between levels in the SoLOD node is based on distance from the camera, which is faster than using screen area.

FIELDS
SoMFFloat
screenArea
Areas to use for comparison

METHODS

SoLevelOfDetail()
Creates a level-of-detail node with default settings.

static SoType
getClassTypeId()
Returns type identifier for this class.

ACTION BEHAVIOR
SoGLRenderAction, SoRayPickAction, SoCallbackAction
Only the child with the appropriate level of detail is traversed.

SoGetBoundingBoxAction
The box that encloses all children is computed. (This is the box that is needed to compute the projected size.)

others
All implemented as for SoGroup.

FILE FORMAT/DEFAULTS
LevelOfDetail {
screenArea	0
}

SEE ALSO
SoLOD, SoComplexity, SoSwitch, SoGroup