pfLODState(3pf) OpenGL Performer 3.2.2 libpf C++ Reference Pages
NAMEpfLODState - Create, modify, and query level of detail state.
FUNCTION SPECIFICATION
#include <Performer/pf/pfLODState.h>
pfLODState::pfLODState();
static pfType * pfLODState::getClassType(void);
void pfLODState::setAttr(long attr, float val);
float pfLODState::getAttr(long attr);
int pfLODState::setName(const char *name);
const char * pfLODState::getName(void);
pfLODState * pfLODState::find(const char *name);
PARENT CLASS FUNCTIONS
The OpenGL Performer class pfLODState is derived from the parent class
pfObject, so each of these member functions of class pfObject are also
directly usable with objects of class pfLODState. This is also true for
ancestor classes of class pfObject.
void* pfObject::operator new(size_t);
void* pfObject::operator new(size_t, pfFluxMemory *fmem);
void pfObject::setUserData(void *data);
void pfObject::setUserData(int slot, void *data);
void* pfObject::getUserData(pfObject *obj);
void* pfObject::getUserData(pfObject *obj, int slot);
int pfObject::getNumUserData();
Since the class pfObject is itself derived from the parent class
pfMemory, objects of class pfLODState can also be used with these
functions designed for objects of class pfMemory.
void* pfMemory::getData(const void *ptr);
pfType * pfMemory::getType();
int pfMemory::isOfType(pfType *type);
int pfMemory::isExactType(pfType *type);
const char * pfMemory::getTypeName();
int pfMemory::copy(pfMemory *src);
int pfMemory::compare(const pfMemory *mem);
void pfMemory::print(uint which, uint verbose, char *prefix,
FILE *file);
int pfMemory::getArena(void *ptr);
void* pfMemory::getArena();
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int pfMemory::ref();
int pfMemory::unref();
int pfMemory::unrefDelete();
int pfMemory::unrefGetRef();
int pfMemory::getRef();
int pfMemory::checkDelete();
int pfMemory::isFluxed();
void * pfMemory::getArena();
int pfMemory::getSize();
PARAMETERS
ls identifies a pfLODState.
DESCRIPTIONpfLODState encapsulates a definition of how an LOD or group of LODs
should respond to distance from the eyepoint and stress. Currently,
there are 8 attributes that can be used to define LOD child selection and
child transition distance based on a LOD's distance from the channel's
viewpoint and the channel's stress (see pfChannel and
pfChannel::setStress).
new pfLODState creates and returns a handle to a pfLODState. pfLODStates
are always allocated from shared memory and cannot be created statically,
on the stack or in arrays. pfLODStates should be deleted using pfDelete
rather than the delete operator.
pfLODState::getClassType returns the pfType* for the class pfLODState.
The pfType* returned by pfLODState::getClassType is the same as the
pfType* returned by invoking the virtual function getType on any instance
of class pfLODState. Because OpenGL Performer allows subclassing of
built-in types, when decisions are made based on the type of an object,
it is usually better to use the member function isOfType to test if an
object is of a type derived from a Performer type rather than to test for
strict equality of the pfType*'s.
pfLODState::setAttr and pfLODState::getAttr are used to set and get the
following attributes:
PFLODSTATE_RANGE_RANGESCALE, PFLODSTATE_RANGE_RANGEOFFSET
directly modify the geometric range used to determine the
current LOD child.
PFLODSTATE_RANGE_STRESSSCALE, PFLODSTATE_RANGE_STRESSOFFSET
modify the way the current channel stress affects the range
computation.
PFLODSTATE_TRANSITION_RANGESCALE, PFLODSTATE_TRANSITION_RANGEOFFSET
directly modify the transition widths set by
pfLOD::setTransition.
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PFLODSTATE_TRANSITION_STRESSSCALE, PFLODSTATE_TRANSITION_STRESSOFFSET
modify the way transition widths are adjusted by the channel
stress value.
These scale and offset values adjust the LOD selection process in the
following way, presented in pseudocode:
effectiveRange =
OverallLODScale *
(Range * RANGE_RANGESCALE + RANGE_RANGEOFFSET) *
(Stress * RANGE_STRESSSCALE + RANGE_STRESSOFFSET);
effectiveTransitionWidth[i] =
OverallFadeScale *
(Trans[i] * TRANSITION_RANGESCALE + TRANSITION_RANGEOFFSET) /
(Stress * TRANSITION_STRESSSCALE + TRANSITION_STRESSOFFSET);
OverallLODScale and OverallFadeScale are the PFLOD_SCALE and PFLOD_FADE
attributes set with pfChanLODAttr. Both are global values that affect the
switching and transition ranges of all pfLODs in the scene.
The default values for all SCALE and OFFSET attributes are 1.0 and 0.0
respectively except TRANSITION_STRESSSCALE and TRANSITION_STRESSOFFSET
which are 0.0 and 1.0 respectively, i.e., transition ranges are not
scaled by stress by default.
A pfLODState influences a pfLOD's behavior in one of 3 ways:
1. Direct reference. A pfLOD may directly reference a pfLODState
with pfLOD::setLODState.
2. Indexed. A pfLOD may index a pfLODState with
pfLOD::setLODStateIndex. When the LOD is evaluated, the indexth
entry of the evaluating pfChannel's pfLODState table is used. A
pfChannel's pfLODState table is set with (-
pfChannel::setLODStateList). With indexed pfLODStates,
different pfChannels can have different LOD behavior by using
different pfLODState tables, e.g., an infrared channel may not
"see" cold objects as well as a visual channel so "cold" pfLODs
will index a different pfLODState in the infrared channel than
in the visual channel.
3. Inherited from pfChannel. A pfLOD which does not directly
reference or index a pfLODState will use the pfLODState of the
evaluating pfChannel (pfChannel::setLODState). This is the
default pfLOD behavior.
When a pfLOD references or indexes a pfLODState, the SCALE and OFFSET
parameters of the pfLODState are multiplied and added, respectively, to
the corresponding SCALE and OFFSET parameters of the evaluating
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pfLODState(3pf) OpenGL Performer 3.2.2 libpf C++ Reference Pages
pfChannel's pfLODState, e.g., effective RANGE_RANGESCALE = pfLODState's
RANGE_RANGESCALE * pfChannel's RANGE_RANGESCALE.
Multiple pfLODs may share the same pfLODState reference or index.
pfLODState::setName and pfLODState::getName set and get the name of a
particular pfLODState while pfLODState::find will return the first
pfLODState defined with the given name.
SEE ALSO
pfLOD, pfChannel
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