Hi David. Thanks for the many suggestions. Unfortunately, the code I'm working
on needs to work with a released version of OSG, so mods to OSG itself are not
an option.
Apparently I overlooked the obvious swap() solution. I've done a quick test and
I believe this will work for me.
And thanks, Peter, for the pointer to the mysharedarray example. This is also a
workable solution, if I encounter problems with swap().
-Paul
On 8/15/2012 5:29 AM, David Callu wrote:
Hi Paul,
2012/8/13 Paul Martz <pma...@skew-matrix.com <mailto:pma...@skew-matrix.com>>
Hi all --
There doesn't seem to be a way to use a custom allocator with an OSG Array
type. Is that correct, or have I missed something?
You're right
I have a large store of array data, and want to create a new instance of an
OSG Array that references that data store without invoking a data copy or
per-element constructor. The typical way to do this in C++ is with a custom
allocator, but as near as I can tell, OSG's Array types don't allow an
allocator as a template parameter.
If I can't use a custom allocator, does anyone have any ideas on how to
create an OSG Array that references a pre-allocated data store?
Any ideas would be appreciated, thanks.
.
OSG Array use an osg::MixinVector<T> template that use a std::vector under the
hood.
I think to some solutions :
1) extend MixinVector template with a second parameter, the CustomAllocator
and pass it to the std::vector used in this template. Then extend
osg::TemplateArray in the same way.
change
typedef TemplateIndexArray<GLbyte,Array::ByteArrayType,1,GL_BYTE> ByteArray;
in
template <AllocT = defaultAlloc>
class ByteArray :
public TemplateIndexArray<GLbyte,Array::ByteArrayType,1,GL_BYTE>
{
...
};
Then adapt ArrayVisitor, ConstArrayVisitor and all dependency to accept a
template instead of a class
class ArrayVisitor
{
template <AllocT = defaultAlloc>
virtual void apply(ByteArray<AllocT>&) {}
...
};
Really big work, and there are some limitations (serialization for example).
(This could be more simple with C++11 new possibility)
2) Change osg::MixinVector<T> in your custom OSG implementation then use
Allocator that you need
and create Vec3ArrayMyAlloc and other osg::Array with your allocator,
extend ArrayVisitor for your new
Arrays types, and so on for all Array's dependency that your code require.
3) Change osg::MixinVector<T> to don't use std::vector anymore (do the vector
stuff yourself)
and add in the public interface a function that allow user to change
Allocator of array element at runtime.
All element of the vector will be remove if you change the allocator to
avoid any memory corruption.
4) You probably already dig this solution but ...
If you can store your "large store of array data" in an std::vector, then
just do a std::swap between std::vector and osg::Array.
5) In the same way of 3) define a custom allocator that could change its
behaviours at runtime, but still use a std::vector.
template<class ValueT>
class MixinVector
{
typedef typename std::vector<ValueT, MyAdaptableAllocator> vector_type;
public:
...
};
Allocator could have a callback mechanism like osg::Node/osg::NodeCallback.
You can do something like this in allocator to don't hurt performance in
default behaviours (with if/else optimization):
void MyAllocator::function()
{
if (callback == NULL)
do stuff
else
callback()
}
Anyway there are no really good solution...
HTH
David
--
-Paul Martz Skew Matrix Software
http://www.skew-matrix.com/
_________________________________________________
osg-users mailing list
osg-users@lists.__openscenegraph.org
<mailto:osg-users@lists.openscenegraph.org>
http://lists.openscenegraph.__org/listinfo.cgi/osg-users-__openscenegraph.org
<http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org>
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
