Re: [osg-users] dynamic_cast of referenced objects

[Kevin Wilder]

Hi,

For anyone who is still following this thread (or for anyone who stumbles upon 
it while trying to solve a similar problem in the future), I figured I'd post 
my findings:

The bit about the object reference pointers vs. standard C++ pointers turned 
out to be a red herring. Seems the crashes resulted from my method of updating 
2D text in the scene. I was just calling -settext(blah) from the main loop 
whenever I wanted to change the displayed characters. The crashes went away 
when I implemented a callback function to update the text. Here's an example of 
my text update callback function:


Code:


struct TextUpdateCallback : public osg::Drawable::UpdateCallback
{
  virtual void update(osg::NodeVisitor* nv, osg::Drawable* drawable)
  {
osgText::Text * TextPointer = dynamic_castosgText::Text*(drawable) ;

if ( TextPointer )
{
  TextPointer-setText(NewText) ;
  TextPointer-setColor(NewColour) ;
}
  }
}



 

I hope this helps.

Cheers,

Kevin[/quote]

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Re: [osg-users] dynamic_cast of referenced objects

[Kevin Wilder]

Hi,

Thank you both for all of your help!

Cheers,

Kevin

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[osg-users] dynamic_cast of referenced objects

[Kevin Wilder]

Hi,

My project is throwing an occasional unhandled win32 exception error and I've 
been trying to figure out why. There is no consistency in the timing so I 
assume that I have a dangling pointer somewhere. (I don't have a memory leak 
because the memory usage shown in the Windows Task Manager is fairly constant 
while my code is running.) 

I came upon a passage in the OpenSceneGraph Quick Start Guide that says:

Be careful when returning the address of an object from a function. If you do 
this incorrectly, the ref_ptr storing the memory address could go out of 
scope before the address is placed on the return stack.

I assume that this also applies when passing referenced objects to a 
function... But most of the examples of callback functions that I have seen on 
the web all use standard C++ pointers in the function definition, rather than 
ref_ptr. For example:

--- snip ---

void operator()( osg::Node* node, osg::NodeVisitor * nv )
{
  osg::MatrixTransform * MatrixXform = 
dynamic_castosg::MatrixTransform*(node) ;

if ( MatrixXform )

--- snip ---

Thinking that this may be the source of my dangling pointer, I tried to modify 
my own callback function definition to use referenced object pointers per the 
quick start guide's recommendations. Unfortunately, I got hung up on the 
dynamic_cast in the code above. I can't figure out how to cast the osg::node 
referenced object pointer into an osg::MatrixTransform referenced object 
pointer.

Is there an equivalant means of casting an osg::ref_ptrosg::node into an 
osg::ref_ptrosg::MatrixTransform when using referenced object pointers? I'm 
trying to do something like:

--- snip ---

void operator()( osg::ref_ptrosg::Node node, osg::ref_ptrosg::NodeVisitor 
nv )
{
  osg::ref_ptrosg::MatrixTransform MatrixXform = 
dynamic_castosg::ref_ptrosg::MatrixTransform(node) ;

if ( MatrixXform )

--- snip ---


Thanks for the help. I'm relatively new to OpenSceneGraph programming.

Cheers,

Kevin

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Re: [osg-users] How to name the viewer window???

[Kevin Wilder]

Hi,

I came upon this post while searching for a way to do exactly the same thing. 
Now that I've found a solution, I thought I would post it for the benefit of 
everyone on this forum:

// create the windows and start the required threads.
viewer.realize();

// add a caption to the viewer window
osgViewer::Viewer::Windows ViewerWindow;
viewer.getWindows(ViewerWindow);
if (!ViewerWindow.empty())
{ 
  ViewerWindow.front()-setWindowName( MyCaption );
}

// Get windows handle for viewer window and set the viewer window icon
hWnd = FindWindow(NULL, _T(MyCaption ); 
HANDLE hIcon = LoadImage(0, MyIcon.ico, IMAGE_ICON, 0, 0, LR_LOADFROMFILE);

if( hIcon  hWnd )
{
  SendMessage(hWnd, WM_SETICON, ICON_SMALL, (LPARAM)hIcon);
}

Cheers,

Kevin

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