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Timestamp:
09/04/15 17:35:24 (3 hours ago)
Author:
robert
Message:

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.
"

Files:
1 modified

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  • OpenSceneGraph/trunk/src/osgWidget/ViewerEventHandlers.cpp

    r13041 r13376  
    2222        _wm->setScrollingMotion(gea.getScrollingMotion()); 
    2323 
    24         return (this->*ma)(gea.getX(), gea.getY(), gea.getButton()); 
     24        // osgWidget assumes origin is bottom left of window so make sure mouse coordinate are increaseing y upwards and are scaled to window size. 
     25        float x = (gea.getX()-gea.getXmin())/(gea.getXmax()-gea.getXmin())*static_cast<float>(gea.getWindowWidth()); 
     26        float y = (gea.getY()-gea.getYmin())/(gea.getYmax()-gea.getYmin())*static_cast<float>(gea.getWindowHeight()); 
     27        if (gea.getMouseYOrientation()==osgGA::GUIEventAdapter::Y_INCREASING_DOWNWARDS) y = static_cast<float>(gea.getWindowHeight())-y; 
     28 
     29        //OSG_NOTICE<<"MouseHandler(x="<<x<<", y="<<y<<")"<<std::endl; 
     30 
     31        return (this->*ma)(x, y, gea.getButton()); 
    2532    } 
    2633