Hi Lingyun,
std::bad_alloc is thrown when operator new cannot allocate memory,
which indicates there is not enough memory. You may reserve your array
before hand, as Paul mentioned, but it may throw as well. This could
reduce, if nothing, copy operations. It may also prevent exception,
because when expanding, std::vector will have two large copies at the
same time. That is:
e.g. old array length was 1500000
expand by 500000
While allocating 2000000 elements, previous 1500000 elements will also
be alive/allocated, that requires room for 3500000 elements in total.
Resize may reduce this cost to 2000000 only, because vector will not
have to expand afterwards (i.e. during push_back), which requires a
copy operation. Note that C++ standard allocator doesn't do realloc().
Instead, vector will allocate a block of N * sizeof(T) items (or
little more), copy existing block into new one, then free existing
block.
// instantiate vertices normally
vertices = new osg::Vec3Array;
// if number of parts is greater than 1000,
// reserve your items before.
if (NumPart > 1000)
{
try
{
vertices->reserve(NumPart);
}
catch (std::bad_alloc& e)
{
// handle exception here; log and return error from this function.
// alternatively, you can rethrow here, and catch in caller.
}
}
// wrap your push_back calls in a try-catch block
try
{
vertices->push_back(...);
}
catch (std::exception&)
{
}
To be on the safe side, handle your exceptions and wrap your pointers
in a smart pointer class. If an exception is thrown and you
rethrow/return from function, you need to delete your Geode, Group and
other objects. You may get all these for free, if you use a smart
pointer (osg::ref_ptr<T>, in this case, as osg::Node's destructor is
protected, IIRC, which prevents it to be "delete"d externally, but
only when its ref count reaches 0).
HTH
Ismail
2009/4/13 Paul Martz <pma...@skew-matrix.com>:
> Hi Lingyun Yu --
> You don't have a variable named 'galaxy' defined, so the
> "addDrawable(galaxy)" is suspicious.
>
> I'd so a resize on the vertex and color arrays, rather than a push_back, for
> efficiency reasons.
>
> I don't think numParts>1000000 should cause any problems. OpenGL doesn not
> place an upper limit on the number of primitives you can render with a
> single glDrawArrays call.
>
> I don't really see anything that would cause a crash so I guess you should
> use a debugger and look at the call stack, like you would any other crash.
>
> Paul Martz
> Skew Matrix Software LLC
> http://www.skew-matrix.com
> +1 303 859 9466
>
>
> -----Original Message-----
> From: osg-users-boun...@lists.openscenegraph.org
> [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Sent:
> Monday, April 13, 2009 9:27 AM
> To: osg-users@lists.openscenegraph.org
> Subject: [osg-users] Problem of points showing
>
> Hi, everybody,
>
> I met a problem when I want to show huge amount of points, as you can see
> the code below, if my NumPart is 1000000, no problem, it shows points
> properly. But if the NumPart is 2000000, then it shows a lot of lines. If
> NumPart is even bigger, the program complained like this：Microsoft C++
> exception: std::bad_alloc at memory location 0x0030e898.
>
> I don't know that's because the dataset is too big or not? because while it
> shows not so many points, everything goes well.
>
> By the way, the data in P array are all right.
>
> osg::Geode *makeGalaxy()
> {
> osg::Geode *geode = new osg::Geode();
> osg::Geometry *geometry= new osg::Geometry();
> osg::Vec3Array *vertices = new osg::Vec3Array();
> osg::Vec4Array *colors = new osg::Vec4Array();
> osg::Vec4 ini(1,0.1,0.55,1);
> osg::Vec4 fin(0,1,0,1);
>
> for (int i = 1; i <= NumPart; i++)
> {
>
> vertices->push_back(osg::Vec3(P[i].Pos[0],P[i].Pos[1],P[i].Pos[2]));
> colors->push_back(ini+(fin-ini)*(i*1/NumPart));
> }
> geometry->setVertexArray(vertices);
> geometry->setColorArray(colors);
> geometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
> geometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS,
> 0, NumPart));
> geode->addDrawable(galaxy);
> return geode;
> }
>
> ...
>
> Thank you.
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=10166#10166
>
>
>
>
>
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