root/OpenSceneGraph/trunk/applications/present3D/deprecated/ShowEventHandler.h @ 13890

Revision 13890, 1.0 kB (checked in by robert, 19 hours ago)

From Jannik Heller, "I've hit what I believe to be a bug (or at the very least, an unintuitive behaviour) in the osg::Geometry copy constructor. I noticed it when using osg::clone on a Geometry with vertex buffer objects, and the copy flags DEEP_COPY_ARRAYS. To be precise, I add a Geometry to an osgUtil::IncrementalCompileOperation?, then osg::clone the Geometry. I was getting reports from users of random crashes happening.

I believe the offending lines are in the osg::Geometry copy constructor:

if ((copyop.getCopyFlags() & osg::CopyOp::DEEP_COPY_ARRAYS))
{

if (_useVertexBufferObjects)
{

// copying of arrays doesn't set up buffer objects so we'll need to force
// Geometry to assign these, we'll do this by switching off VBO's then renabling them.
setUseVertexBufferObjects(false);
setUseVertexBufferObjects(true);

}

}

Toggling the vertex buffer objects off then on again actually touches not only the arrays controlled by DEEP_COPY_ARRAYS, but also the PrimitiveSets? which are controlled by DEEP_COPY_PRIMITIVES. This means if the user has copyflags of only DEEP_COPY_ARRAYS, we are modifying arrays that belong to the original const Geometry& we are copying from. I believe this shouldn't be allowed to happen because we are using a const& specifier for the original Geometry.

In my case the osgUtil::IncrementalCompileOperation? was trying to compile the geometry, while in the main thread a clone operation toggled the VBO's off and on, a crash ensues.

In the attached patch, you will find a more efficient handling of VBO's in the osg::Geometry copy constructor, so that only the Arrays that were actually deep copied have their VBO assigned, and no changes are made to Arrays that already had a valid VBO assigned. In addition, the DEEP_COPY_PRIMITIVES flag is now honored so that VBO's are set up correctly should a user copy a Geometry with only that flag.
"

  • Property svn:eol-style set to native
Line 
1/* -*-c++-*- Present3D - Copyright (C) 1999-2006 Robert Osfield
2 *
3 * This software is open source and may be redistributed and/or modified under
4 * the terms of the GNU General Public License (GPL) version 2.0.
5 * The full license is in LICENSE.txt file included with this distribution,.
6 *
7 * This software is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10 * include LICENSE.txt for more details.
11*/
12
13#ifndef SHOWEVENTHANDLER
14#define SHOWEVENTHANDLER 1
15
16#include <osg/StateSet>
17#include <osg/Point>
18
19#include <osgGA/GUIEventHandler>
20
21namespace p3d
22{
23
24class ShowEventHandler : public osgGA::GUIEventHandler
25{
26    public:
27
28        ShowEventHandler();
29
30        virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa, osg::Object* object, osg::NodeVisitor* nv);
31
32        virtual void getUsage(osg::ApplicationUsage& usage) const;
33
34};
35
36}
37
38#endif
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