The fix was to check whether glGetString( GL_VERSION ) returned a null pointer (Ref. svn diff below). The altered src/osg/GLExtensions.cpp is zipped and attached to this email."
set.
The optimization is based on the observation that matrix matrix multiplication
with a dense matrix 4x4 is 4^3 Operations whereas multiplication with a
transform, or scale matrix is only 4^2 operations. Which is a gain of a
*FACTOR*4* for these special cases.
The change implements these special cases, provides a unit test for these
implementation and converts uses of the expensiver dense matrix matrix
routine with the specialized versions.
Depending on the transform nodes in the scenegraph this change gives a
noticable improovement.
For example the osgforest code using the MatrixTransform is about 20% slower
than the same codepath using the PositionAttitudeTransform instead of the
MatrixTransform with this patch applied.
If I remember right, the sse type optimizations did *not* provide a factor 4
improovement. Also these changes are totally independent of any cpu or
instruction set architecture. So I would prefer to have this current kind of
change instead of some hand coded and cpu dependent assembly stuff. If we
need that hand tuned stuff, these can go on top of this changes which must
provide than hand optimized additional variants for the specialized versions
to give a even better result in the end.
An other change included here is a change to rotation matrix from quaterion
code. There is a sqrt call which couold be optimized away. Since we divide in
effect by sqrt(length)*sqrt(length) which is just length ...
"
they are written to disk, either inline or as an external file. Added support for
this in the .ive plugin. Default of WriteHint is NO_PREFERNCE, in which case it's
up to the reader/writer to decide.
occlusion query result is not ready for retrieval when the app tries to
retrieve it. This fix adds an application-level wait loop to ensure the
result is ready for retrieval. This code is not compiled by default; add "-D
FORCE_QUERY_RESULT_AVAILABLE_BEFORE_RETRIEVAL" to get this code.
Full, gory details, to the best of my recollection:
The conditions under which we encountered this issue are as follows: 64-bit
processor, Mac/Linux OS, multiple NVIDIA GPUs, multiple concurrent draw
threads, VRJuggler/SceneView-based viewer, and a scene graph containing
OcclusionQueryNodes. Todd wrote a small test program that produces an almost
instant crash in this environment. We verified the crash does not occur in a
similar environment with a 32-bit processor, but we have not yet tested on
Windows and have not yet tested with osgViewer.
The OpenGL spec states clearly that, if an occlusion query result is not yet
ready, an app can go ahead and attempt to retrieve it, and OpenGL will
simply block until the result is ready. Indeed, this is how
OcclusionQueryNode is written, and this has worked fine on several platforms
and configurations until Todd's test program.
By trial and error and dumb luck, we were able to workaround the crash by
inserting a wait loop that forces the app to only retrieve the query after
OpenGL says it is available. As this should not be required (OpenGL should
do this implicitly, and more efficiently), the wait loop code is not
compiled by default. Developers requiring this work around must explicitly
add "-D FORCE_QUERY_RESULT_AVAILABLE_BEFORE_RETRIEVAL" to the compile
options to include the wait loop."
New attribute DatabasePager::_expiryFrames sets number of frames a PagedLOD child is kept in memory. The attribute is set with DatabasePager::setExpiryFrames method or OSG_EXPIRY_FRAMES environmental variable.
New attribute PagedLOD::PerRangeData::_
frameNumber contains frame number of last cull traversal.
Children of PagedLOD are expired when time _AND_ number of frames since last cull traversal exceed OSG_EXPIRY_DELAY _AND_ OSG_EXPIRY_FRAMES respectively. By default OSG_EXPIRY_FRAMES = 1 which means that nodes from last cull/rendering
traversal will not be expired even if last cull time exceeds OSG_EXPIRY_DELAY. Setting OSG_EXPIRY_FRAMES = 0 revokes previous behaviour of PagedLOD.
Setting OSG_EXPIRY_FRAMES > 0 fixes problems of children reloading in lazy rendering applications. Required behaviour is achieved by manipulating OSG_EXPIRY_DELAY and OSG_EXPIRY_FRAMES together.
Two interface changes are made:
DatabasePager::updateSceneGraph(double currentFrameTime) is replaced by DatabasePager::updateSceneGraph(const osg::FrameStamp &frameStamp). The previous method is in #if 0 clause in the header file. Robert, decide if You want to include it.
PagedLOD::removeExpiredChildren(double expiryTime, NodeList &removedChildren) is deprecated (warning is printed), when subclassing use PagedLOD::removeExpiredChildren(double expiryTime, int expiryFrame, NodeList &removedChildren) instead. "
