[osg-users] Geometry vertices and nan/inf

Erik Hensens

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Mar 14, 2015, 11:06:21 AM3/14/15

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Hello all,

I'm analyzing the vertices of a geometry like so:

Code:

osg::Array *pVertexArray = pGeometry->getVertexArray();
int nVertices = (int)(pVertexArray->getNumElements());
osg::Vec3 *pVertexData = (osg::Vec3 *)(pVertexArray->getDataPointer());
for (int i = 0; i < nVertices; i++)
{
float fVertexX = (pVertexData + i)->x();
float fVertexY = (pVertexData + i)->y();
float fVertexZ = (pVertexData + i)->z();
...
}

And sometimes these vertex x(), y(), and/or z() parameters are nan or inf. Am I doing something wrong? I don't understand how this would happen.

Thanks a bunch!

Cheers,
Erik

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Robert Osfield

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Mar 14, 2015, 11:46:27 AM3/14/15

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Hi Erik,

Your code is rather perverse and potentially unsafe way to get at the xyz coords, but if the array is a Vec3Array then it should probably work OK.

A better way to look at to coords is to cast the array to a Vec3Array and access the vertices via the std::vector<> methods (Vec3Array subclasses from std::vector<>) i.e.

osg::Vec3Array* vertices = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());

if (vetices)

{

for(unsigned int i=0; i<vertices->size(); ++i)

{

osg::Vec3& vertex = (*vertices)[i];

std::cout<<"x="<<vertex.x()<<", y="<<vertex.y()<<", "<<vertex.z()<<std::endl;

}

Robert.

Erik Hensens

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Mar 16, 2015, 12:44:32 PM3/16/15

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robertosfield wrote:
> Your code is rather perverse and potentially unsafe way to get at the xyz coords, but if the array is a Vec3Array then it should probably work OK.
>
>
> A better way to look at to coords is to cast the array to a Vec3Array and access the vertices via the std::vector<> methods (Vec3Array subclasses from std::vector<>) i.e.
>
>
> osg::Vec3Array* vertices = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());
> if (vetices)
> {
> for(unsigned int i=0; i<vertices->size(); ++i)
> {
> osg::Vec3& vertex = (*vertices)[i];
> std::cout<<"x="<<vertex.x()<<", y="<<vertex.y()<<", "<<vertex.z()<<std::endl;
> }
> }
>
>
> Robert.
>

Hi Robert,

Thank you very much for your response. I don't understand how my code was potentially unsafe. Getting the type via pVertexArray->getType() returns Vec3ArrayType, shouldn't all Geometry vertex arrays be of this type?

As per my original question about non-real floating point coordinates, I believe I may be to blame; I might have accidentally set some non-real values as vertex x, y, and/or z values when building the Geometry in the first place. I am currently working on verifying whether or not this is so.

I suppose what surprised me was that OSG was able to draw the Geode that used the Geometry with the occasional nan/+inf/-inf vertex x/y/z parameter without any issues.