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 ...
"
osgText/Text.cpp: Line 502
...
else
{
++itr;
}
if (itr!=_text.end())
{
// skip over spaces and return.
while (*itr==' ') ++itr; // New
if (*itr=='\n') ++itr;
}
// move to new line.
switch(_layout)
{
.."
attached code adds this, along with a member variable to keep track of
the setting. It is based on the latest subversion version, and was
tested by creating a new text object with the same axis alignment as an
existing one (e.g.
new_text->setAxisAlignment(old_text->getAxisAlignment()); )."
From Robert Osfield, " I originally didn't add a getAxisAlignment()
as all setAxisAlignment does is set the Rotation member variable, and
potentially one could apply user defined Rotation setting after the
setAxisAlignment() which would bring it out of sync with the
setAxisAlignment.
Rather than reject your submission on the ground of potentially
getting out of sync and therefore misleading users I've added a
USED_DEFINED_ROTATION to AxisAlignment enum, and set this in the
serRotation and then override this setting of _axisAlignment in the
setAxisAlingment method. I've also removed the lazy updating
optimization you've added to the top of setAxisAlignment to avoid
potential problems as well."
