Also I've done the osguserstats example. I've kept the "toy example" that was in the modified osgviewer.cpp I had sent you, because they show different uses of custom stats lines (a value displayed directly, a value without bars and a value with bars and graph). I also added a function and a thread that will sleep for a given number of milliseconds and record this time in the stats. I think it clearly shows how to record the time some processing takes and add that to the stats graph, whether the processing takes place on the same thread as the viewer or on another thread.
BTW, feel free to modify the colors I've given to each user stats line... I'm not very artistic. :-)
I've also added more doc comments to the addUserStats() method in ViewerEventHandlers, so hopefully the arguments are clear and the way to get the results you want is also clear. Maybe I went overboard, but the function makes some assumptions that may not be obvious and has many arguments, so I preferred to be explicit."
A new AutoRotateMode was added. I named it ROTATE_TO_AXIS to be
consistent with the other AutoRotateModes, even though it changes from
how is called in Billboard (AXIAL_ROT).
Setters and getters for rotation axis and normal were also added to the
AutoTransform class interface.
The implementation is mainly a copy-paste from Billboard code.
"
- Algorithm doesn't try to merge double and single precision arrays together
- Algorithm doesn't try to merge incompatible geometries (ex: one with "vertices + texoords", and another with only vertices)
2. Better TextureAtlasBuilder
Algorithm is still sub-optimal, but it now tries to fill more blanks, using "unused space in the current line".
(Don't know if I already submitted it, but I guess not)
One day, someone should try to find a good solution to this NP-problem... For instance : http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.140.200&rep=rep1&type=pdf
"
The user calls statsHandler->addUserStatsLine() providing:
- the label they want for that line in the graph
- the text and bar colors they want in the graph
- the stats names they want queried (one for time taken, one for begin and one for end time) and a few settings for how these will be displayed.
Then all they have to do is call viewer->getViewerStats()->setAttribute(framenumber, name, value) for their three attributes each frame and they'll have their stats in the graph.
They can also give only a time taken attribute (or some other numerical value they want printed, which can be averaged or not), or only begin+end attributes, and the graph will accordingly display only the (average or not) numerical value or only the bars.
Along the way I cleaned up the existing code a bit:
* Each time the setUpScene() or createCameraTimeStats() methods added a line to the graph, they did pretty much the same thing, so I moved that into a separate method called createTimeStatsLine() which is called by setUpScene() and createCameraTimeStats().
* I moved the font, characterSize, startBlocks and leftPos variables to member variables, since they were being passed around everywhere but were set only once at the beginning.
* The geode on which stats lines are added is also kept in a member variable, and createCameraTimeStats() adds the per-camera lines to this geode instead of returning a new Group with a new Geode. This further reduces the number of variables the createCameraTimeStats() method needs as input.
"
to download the texture object to graphics card.
Calling IncrementalCompileOperation::assignForceTextureDownloadGeometry() assigns a geometry
to the job.
changed extensions from .c to .cpp and got compiling as C files as part of the osg core library.
Updated and cleaned up the rest of the OSG to use the new internal GLU.
change was to use doubles for reading and writing matrices regardless of type of Matrix
being serialized.
Change does break backwards compatibility though, so code
path supporting original format has been left in for the
time being. However, this code is not reliable enough and
is over complicated compared to the simplified handling. Once
the new code has been bedded down for a while I'll remove this code block.
I also fixed a possible bug in osgDB::XmlParser that doesn't handle control characters (like " to ") when reading node attributes, because the writeWrappedString() and readWrappedString() now depend heavily on control characters. An additional improvement is that osgx now supports comments."
osg/Camera. The ::glName issue masked the fact that the "(..)" isn't handled
well in doxygen and leads to "(." in the generated files.
I'm also submitting a minor documentation fix to osgGA/DriveManipulator to get
it out of my patch queue ;)"
performance option, I added a flag to control whether the depth writing
pass is performed.
Since text is alpha-blended when rendering, it is placed in the
transparent bin and rendered back to front. Writing to the depth buffer
should therefore be unnecessary. Indeed, rendering something behind text
(or any blended object) after that object is drawn will give incorrect
results whether the depth buffer is written or not. I therefore think it
is safe to keep this option off by default. Users can turn it on for any
special needs they have.
I did not fix the existing backdrop implementations to work with the new
code since this new method of rendering intrinsically handles backdrops
correctly. Its results are more accurate than all of the existing
backdrop implementations. Its only downside is that it requires two
passes if depth buffer updates are desired, whereas DEPTH_RANGE and
POLYGON_OFFSET achieve their (less accurate) results in one pass. The
NO_DEPTH_BUFFER method also only uses one pass, but it disables depth
tests and not depth writes so will have serious problems if anything is
drawn in front of the text before OR after the text is drawn.
Given the better all-around behavior of the new method, I believe the
other backdrop implementations can be safely removed. Code that adjusts
the backdrop implementation will of course be broken if the member
functions are removed. For this reason I left them in, but set the new
rendering method as the default backdrop implementation. At the very
least I think the old backdrop implementations should be deprecated and
removed at a later date.
"
Note from Robert Osfield, testing this submission with osgtext I found that the
text would not render correctly when different text labels were overlapping
in deth and screen space. I change _enableDepthWrites to default to true and
found the that which artifacts still occurred around the alpha blended edges
the artifacts where better than issue with occlusion of nearer pixels that was
happening with _enableDepthWrites set to false.I therefore set the
_enableDepthWrites to true as I feel it's the lesser of the two artefacts.
I move declaration of classes TestResult, QueryGeometry from cpp to header file and made a void createSupportNodes() a virtual method.
Now is possible to inherit from class OcclusionQueryNode."
Goals:
- to handle INCR_WRAP values nicely if not supported by OpenGL (old hardware)
- to support two side stenciling of OpenGL 2.0. Current implementation does not work on ATI as it uses Nvidia extension.
Ready for commit:
- Stencil and Stencil.cpp - please, review them
Ready with "hack":
- StencilTwoSided.cpp: please, see the line 113 in apply():
glEnable(GL_STENCIL_TEST_TWO_SIDE);
This line used to be in getModeUsage() as
usage.usesMode(GL_STENCIL_TEST_TWO_SIDE);
but it produces OpenGL errors on ATI as it is unknown value there (it is Nvidia extension).
Problems with my "glEnable" solution:
- it enables two side stenciling forever, and it will disturb any other single-side stenciling in the scene graph.
"
All size() methods are now renamed to volume(). At present only the CompositePlacer will use it for randomly choose a place according to the volumes of all children.
"
type is supported at present. The attached osgparticleshader.cpp will
show how it works. It can also be placed in the examples folder. But I
just wonder how this example co-exists with another two (osgparticle
and osgparticleeffect)?
Member variables in Particle, including _alive, _current_size and
_current_alpha, are now merged into one Vec3 variable. Then we can
make use of the set...Pointer() methods to treat them as vertex
attribtues in GLSL. User interfaces are not changed.
Additional methods of ParticleSystem are introduced, including
setDefaultAttributesUsingShaders(), setSortMode() and
setVisibilityDistance(). You can see how they work in
osgparticleshader.cpp.
Additional user-defined particle type is introduced. Set the particle
type to USER and attach a drawable to the template. Be careful because
of possible huge memory consumption. It is highly suggested to use
display lists here.
The ParticleSystemUpdater can accepts ParticleSystem objects as child
drawables now. I myself think it is a little simpler in structure,
than creating a new geode for each particle system. Of course, the
latter is still compatible, and can be used to transform entire
particles in the world.
New particle operators: bounce, sink, damping, orbit and explosion.
The bounce and sink opeartors both use a concept of domains, and can
simulate a very basic collision of particles and objects.
New composite placer. It contains a set of placers and emit particles
from them randomly. The added virtual method size() of each placer
will help determine the probability of generating.
New virtual method operateParticles() for the Operator class. It
actually calls operate() for each particle, but can be overrode to use
speedup techniques like SSE, or even shaders in the future.
Partly fix a floating error of 'delta time' in emitter, program and
updaters. Previously they keep the _t0 variable seperately and compute
different copies of dt by themseleves, which makes some operators,
especially the BounceOperator, work incorrectly (because the dt in
operators and updaters are slightly different). Now a getDeltaTime()
method is maintained in ParticleSystem, and will return the unique dt
value (passing by reference) for use. This makes thing better, but
still very few unexpected behavours at present...
All dotosg and serialzier wrappers for functionalities above are provided.
...
According to some simple tests, the new shader support is slightly
efficient than ordinary glBegin()/end(). That means, I haven't got a
big improvement at present. I think the bottlenack here seems to be
the cull traversal time. Because operators go through the particle
list again and again (for example, the fountain in the shader example
requires 4 operators working all the time).
A really ideal solution here is to implement the particle operators in
shaders, too, and copy the results back to particle attributes. The
concept of GPGPU is good for implementing this. But in my opinion, the
Camera class seems to be too heavy for realizing such functionality in
a particle system. Myabe a light-weight ComputeDrawable class is
enough for receiving data as textures and outputting the results to
the FBO render buffer. What do you think then?
The floating error of emitters
(http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2009-May/028435.html)
is not solved this time. But what I think is worth testing is that we
could directly compute the node path from the emitter to the particle
system rather than multiplying the worldToLocal and LocalToWorld
matrices. I'll try this idea later.
"
Texture.cpp:applyTexImage2D_subload:
<code>
unsigned char* data = = (unsigned char*)image->data();
if (needImageRescale) {
// allocates rescale buffer
data = new unsigned char[newTotalSize];
// calls gluScaleImage into the data buffer
}
const unsigned char* dataPtr = image->data();
// subloads 'dataPtr'
// deletes 'data'
</code>
In effect, the scaled data would never be used.
I've also replaced bits of duplicate code in Texture1D/2D/2DArray/3D/Cubemap/Rectangle
that checks if the texture image can/should be unref'd with common functionality in
Texture.cpp.
"
osgWidget::Input:
[Functional changes]
- Previously, the field would be filled with spaces up to its max length, and typing would just replace the spaces. Also, there was a _textLength variable that kept track of the real length of text in the field, since the osgText::Text's length just reflected the length of spaces+text entered. This was not great, as you could still select the spaces with the mouse and it just feels hacky. So I changed it to only contain the text entered, no spaces, and _textLength was removed since it's now redundant (the osgText::Text's length is used instead).
- Fixed the selection size which (visually only) showed one more character selected than what was really selected.
- Fixed selection by dragging the mouse, it would sometimes not select the last character of the string.
- Cursor will now accurately reflect whether insert mode is activated (block cursor) or we're in normal mode (line cursor) like in most editors.
- Implemented Ctrl-X (cut)
- Added a new clear() method that allows the field to be emptied correctly. Useful for a command line interface, for example (hint, hint).
- Mouse and keyboard event handler methods would always return false, which meant selecting with the mouse would also rotate the trackball, and typing an 's' would turn on stats.
[Code cleanup]
- Renamed the (local) _selectionMin and _selectionMax variables which are used in a lot of places, as the underscores would lead to think they were members. Either I called them selection{Min|Max} or delete{Min|Max} where it made more sense.
- Fixed some indenting which was at 3 spaces (inconsistently), I'm sure I didn't catch all the lines where this was the case though.
- Put spaces between variable, operator and value where missing, especially in for()s. Again I only did this where I made changes, there are probably others left.
The result is that delete, backspace, Ctrl-X, Ctrl-C, Ctrl-V, and typing behaviour should now be consistent with text editor conventions, whether insert mode is enabled or not. I hope. :-)
Note, there's a nasty const_cast in there. Why isn't osgText::Font::getGlyph() declared const?
Also, as a note, the current implementation of cut, copy and paste (in addition to being Windows only, yuck) gets and puts the data into an std::string, thus if the osgText::String in the field contains unicode characters I think it won't work correctly. Perhaps someone could implement a proper clipboard class that would be cross-platform and support osgText::String (more precisely other languages like Chinese) correctly? Cut, copy and paste are not critical to what I'm doing so I won't invest the time to do that, but I just thought I'd mention it.
"
"enable thread locking in libavcodec
This is required for a multithreaded application using ffmpeg from
another thread."
"Prevent the audio from videos from hanging on exit if they are paused.
The video decoder already has similar logic."
"Add a way to retrieve the creation time for MPEG-4 files."
"fmpeg, improve wait for close logic
Both audio and video destructors have been succesfully using the logic,
if(isRunning())
{
m_exit = true;
join();
}
since it was introduced,
but the close routines are using,
m_exit = true;
if(isRunning() && waitForThreadToExit)
{
while(isRunning()) { OpenThreads::Thread::YieldCurrentThread(); }
}
which not only is it doing an unnecessary busy wait, but it doesn't
guaranteed that the other thread has terminated, just that it has
progressed far enough that OpenThreads has set the thread status as
not running. Like the destructor set the m_exit after checking
isRunning() to avoid the race condition of not getting to join()
because the thread was running, but isRunning() returns false.
Now that FFmpeg*close is fixed, call it from the destructor as well
to have that code in only one location."
about the Observer header:
/home/cubicool/local/include/osg/Observer: In copy constructor
?osg::ObserverSet::ObserverSet(const osg::ObserverSet&)?:
/home/cubicool/local/include/osg/Observer:66: warning: base class ?class
osg::Referenced? should be explicitly initialized in the copy
constructor
I've been fixing this by hand by using the attached Observer header; it
does exactly what the warning requests. Purely cosmetic, I believe, but
other than that OSG seems to compile w/ -W -Wall just fine."
* Added support for floating windows and context menus in QMDIAreas.
* Protected the size (_width and _height) by a mutex to prevent threading problems.
Then my own:
* Made sure the embedded widget's size follows the graphicsView's size at all times so that window resizes will resize the widget as expected in fullscreen mode."
creation of main shader to ShaderComposer and
collection of ShaderComponent to osg::State.
Also added very basic shader set up in osgshadecomposition example.
to get QWidgetImage to a point where it can fill a need we have: to be
able to use Qt to make HUDs and to display widgets over / inside an OSG
scene.
---------------
Current results
---------------
I've attached what I have at this point. The modified QWidgetImage +
QGraphicsViewAdapter classes can be rendered fullscreen (i.e. the Qt
QGraphicsView's size follows the size of the OSG window) or on a quad in
the scene as before. It will let events go through to OSG if no widget
is under the mouse when they happen (useful when used as a HUD with
transparent parts - a click-focus scheme could be added later too). It
also supercedes Martin Scheffler's submission because it adds a
getter/setter for the QGraphicsViewAdapter's background color (and the
user can set their widget to be transparent using
widget->setAttribute(Qt::WA_TranslucentBackground) themselves).
The included osgQtBrowser example has been modified to serve as a test
bed for these changes. It has lots more command line arguments than
before, some of which can be removed eventually (once things are
tested). Note that it may be interesting to change its name or split it
into two examples. Though if things go well, the specific QWebViewImage
class can be removed completely and we can consolidate to using
QWidgetImage everywhere, and then a single example to demonstrate it
would make more sense, albeit not named osgQtBrowser... You can try this
path by using the --useWidgetImage --useBrowser command line arguments -
this results in an equivalent setup to QWebViewImage, but using
QWidgetImage, and doesn't work completely yet for some unknown reason,
see below.
----------------
Remaining issues
----------------
There are a few issues left to fix, and for these I request the
community's assistance. They are not blockers for me, and with my
limited Qt experience I don't feel like I'm getting any closer to fixing
them, so if someone else could pitch in and see what they can find, it
would be appreciated. It would be really nice to get them fixed, that
way we'd really have a first-class integration of Qt widgets in an OSG
scene. The issues are noted in the osgQtBrowser.cpp source file, but
here they are too:
-------------------------------------------------------------------
QWidgetImage still has some issues, some examples are:
1. Editing in the QTextEdit doesn't work. Also when started with
--useBrowser, editing in the search field on YouTube doesn't
work. But that same search field when using QWebViewImage
works... And editing in the text field in the pop-up getInteger
dialog works too. All these cases use QGraphicsViewAdapter
under the hood, so why do some work and others don't?
a) osgQtBrowser --useWidgetImage [--fullscreen] (optional)
b) Try to click in the QTextEdit and type, or to select text
and drag-and-drop it somewhere else in the QTextEdit. These
don't work.
c) osgQtBrowser --useWidgetImage --sanityCheck
d) Try the operations in b), they all work.
e) osgQtBrowser --useWidgetImage --useBrowser [--fullscreen]
f) Try to click in the search field and type, it doesn't work.
g) osgQtBrowser
h) Try the operation in f), it works.
2. Operations on floating windows (--numFloatingWindows 1 or more).
Moving by dragging the titlebar, clicking the close button,
resizing them, none of these work. I wonder if it's because the
OS manages those functions (they're functions of the window
decorations) so we need to do something special for that? But
in --sanityCheck mode they work.
a) osgQtBrowser --useWidgetImage --numFloatingWindows 1
[--fullscreen]
b) Try to drag the floating window, click the close button, or
drag its sides to resize it. None of these work.
c) osgQtBrowser --useWidgetImage --numFloatingWindows 1
--sanityCheck
d) Try the operations in b), all they work.
e) osgQtBrowser --useWidgetImage [--fullscreen]
f) Click the button so that the getInteger() dialog is
displayed, then try to move that dialog or close it with the
close button, these don't work.
g) osgQtBrowser --useWidgetImage --sanityCheck
h) Try the operation in f), it works.
3. (Minor) The QGraphicsView's scrollbars don't appear when
using QWidgetImage or QWebViewImage. QGraphicsView is a
QAbstractScrollArea and it should display scrollbars as soon as
the scene is too large to fit the view.
a) osgQtBrowser --useWidgetImage --fullscreen
b) Resize the OSG window so it's smaller than the QTextEdit.
Scrollbars should appear but don't.
c) osgQtBrowser --useWidgetImage --sanityCheck
d) Try the operation in b), scrollbars appear. Even if you have
floating windows (by clicking the button or by adding
--numFloatingWindows 1) and move them outside the view,
scrollbars appear too. You can't test that case in OSG for
now because of problem 2 above, but that's pretty cool.
4. (Minor) In sanity check mode, the widget added to the
QGraphicsView is centered. With QGraphicsViewAdapter, it is not.
a) osgQtBrowser --useWidgetImage [--fullscreen]
b) The QTextEdit and button are not in the center of the image
generated by the QGraphicsViewAdapter.
c) osgQtBrowser --useWidgetImage --sanityCheck
d) The QTextEdit and button are in the center of the
QGraphicsView.
-------------------------------------------------------------------
As you can see I've put specific repro steps there too, so it's clear
what I mean by a given problem. The --sanityCheck mode is useful to see
what should happen in a "normal" Qt app that demonstrates the same
situation, so hopefully we can get to a point where it behaves the same
with --sanityCheck and without."
I changed
_in->setStream( new std::stringstream(data) );
to
_dataDecompress = new std::stringstream(data);
_in->setStream( _dataDecompress );
Then when the destructor is of InputStream is called I delete the
dataDecompress stringstream.
"
1) some time values were passed as floats, reducing accuracy.
2) comparisons done between doubles and floats gave different results so time < endtime evaluated to false the first time it was checked (with doubles), and true the second time it was checked (with time having been converted to a float). This consequently resulted in an array-out-of-bounds crash
will cause the writing of osg::Switch incorrectly. The original thread
was posted on osg-users. I would like to follow the suggestion of
Brendan and add a std::endl before the END_BRACKET in
ListSerializer::write().
"
osg::Camera* c = createCamera();
c->attach( osg::Camera::COLOR_BUFFER0, texture3d, 0,
osg::Camera::FACE_CONTROLLED_BY_GEOMETRY_SHADER );
it works also for cubemap textures and 2d texture arrays
"
bool observer_ptr<>::lock(ref_ptr<T>&) to avoid the temporary ref_ptr<>'s
being created and destroyed on the stack along with the associated ref/unref() operations
Changes:
- new mouse wheel zoom/movement/center functionality
- ability to fix vertical axis (important for CAD)
- possibility to specify values as absolute values or relative to model size
- kind of backward compatibility by flags passed to constructor
- and much more
- restructuring classes to use kind of hierarchy and standard way of event processing (handle methods). This way, there is much more code reusability and it is more easy to develop new kinds of manipulators.
Briefly, the new architecture keeps MatrixManipulator as base abstract class. StandardManipulator is the feature-rich standard manipulator with two main descendant classes: OrbitManipulator and FirstPersonManipulator. OrbitManipulator is base class for all trackball style manipulators, based on center, rotation and distance from center. FirstPersonManipulator is base for walk or fly style manipulators, using position and rotation for camera manipulation.
"
Changes by Robert: Replaced osg::Vec3 by osg::Vec3d, introduced DEFAULT_SETTINGS enum and usage. Added frame time member variables in prep for improving throw animation when vysync is off.
the OutputStream/InputStream implementations, which was just finished
last weekend with a few tests on Windows and Ubuntu. Hope it could
work and get more feedbacks soon.
I've added a new option "SchemaData" to the osg2 plugin. Developers
may test the new feature with the command line:
# osgconv cow.osg cow.osgb -O SchemaData
It will record all serializer properties used in the scene graph, at
the beginning of the generated file. And when osgviewer and user
applications is going to read the osgb file, the inbuilt data will be
automatically read and applied first, to keep backwards compatibility
partly. This will not affect osgb files generated with older versions.
"
in process: a wrong definition of the OSG_FATAL macro, and wrong logic
inside the KeySwitchMatrixManipulator::getDistance() function. I
believe both were slips."
META_OSGMANIPULATOR_Object macro to ensure these classes could work
with their wrappers, and a few naming styles should be changed as
well. Fortunately everything seems to compile fine under Windows and
my new Ubuntu system.
And I finally find the problem of the
serializers/osgTerrain/Terrain.cpp, it just missed an "osg::Group"
before "osg::CoordinateSystemNode" indicator. With the small fix
attached now VPB could generate terrain with osgt/osgb formats."
Texture2DMultismaple as name suggests provides means to directly access subsamples of rendered FBO target. (GLSL 1.5 texelFetch call).
Recently I was working on deferred renderer with OSG, during that I noticed there is no support for multisampled textures (GL_ARB_texture_multisample extension). After consultations with Paul Martz and Wojtek Lewandowski I added Texture2DMultisample class and made few necessary changes around osg::FrameBufferObject, osg::Texture and osgUtil::RenderStage classes."
and from follow email:
"Fixed. According to ARB_texture_multisample extension specification multisample textures don't need TexParameters since they can only be fetched with texelFetch."
modifications of the osgShadow header naming styles as well. The
osgDB::Serializer header is also changed to add new Vec2 serializer
macros because of the needs of osgShadow classes. It should compile
fine on both Windows and Linux. But I have only done a few tests to
generate .osgb, .osgt and .osgx formats with these new wrappers."
few headers and the osgAnimation sources are also modified to make
everything goes well, including:
A new REGISTER_OBJECT_WRAPPER2 macro to wrap classes like
Skeleton::UpdateSkeleton.
A bug fix in the Seralizer header which avoids setting default values
to objects.
Naming style fixes in osgAnimation headers and sources, also in the
deprecated dotosg wrappers.
A bug fix for the XML support, to write char values correctly.
A small change in the osg::Geometry wrapper to ignore the
InternalGeometry property, which is used by the MorphGeometry and
should not be set by user applications.
The avatar.osg, nathan.osg and robot.osg data files all work fine with
serializers, with some 'unsupported wrapper' warnings when converting.
I'm thinking of removing these warnings by disabling related property
serializers (ComputeBoundingBoxCallback and Drawable::UpdateCallback),
which are seldom recorded by users.
By the way, I still wonder how would we handle the C4121 problem,
discussed some days before. The /Zp compile option is set to 16 in the
attached cmake script file. And is there a better solution now?"
now O(n) rather than O(nlogn) where n is the number of requests. The refactoring also cleans up the access of the
request lists so that the code is more readable/maintainable.
using osgDB::XmlParser. The extension for XML-formatted scenes is
.osgx, corresponding to .osgb for binary and .osgt for ascii. It could
either be rendered in osgviewer or edited by common web browsers and
xml editors because of a range of changes to fit the XML syntax. For
example, the recorded class names are slight modified, from
'osg::Geode' to 'osg--Geode'.
To quickly get an XML file:
# ./osgconv cow.osg cow.osgx
The StreamOperator header, InputStreram and OutputStream classes are
modified to be more portable for triple ascii/binary/XML formats. I
also fixed a bug in readImage()/writeImage() to share image objects if
needed.
The ReaderWriterOSG2 class now supports all three formats and
reading/writing scene objects (not nodes or images), thanks to
Torben's advice before.
"
This change should make it possible to delete PagedLOD's independantly from the DatabasePager, and also prevent issues of
consistency of the pager when subgraphs when are cached elsewhere in the application such as in the Registry filecache.
up vector to setViewMatrixAsLookAt(..) codes in osgShadow. This will addresses previous issues that occured when look vectors
co-incided with the hard coded up vectors.
