[Solved] getSceneNodeFromCameraBB() not behaving as expected

[cat.exe]

Hello! Once again, I have a problem I was hoping someone could help with.

This time my question is regarding ISceneCollisionManager::getSceneNodeFromCameraBB(), and selecting nodes. The goal was, in this part of my project, to be able to select an arbitrary node in the scene and have it become wireframe; the selection process is triggered by pointing at a node and right-clicking on the mouse. Nodes are deselected simply by pointing anywhere and clicking (or at another node to deselect and select at the same time.)

The issue is that even when the right mouse button is pressed and the observer is not aiming at a node, getSceneNodeFromCameraBB() seems to not return null. I say this because pointedNode, the variable I have getSceneNodeFromCameraBB() return into, comes up true when checked to ensure it is not null, (in line 9) causing a segmentation fault in line ten where it is accessed.

Code: Select all

 
if (receiver->rightMouseButtonPressed())
{
    scene::ISceneNode* pointedNode = smgr->getSceneCollisionManager()->getSceneNodeFromCameraBB(camera, -1);
 
    if (selected != 0)
        ((scene::IMeshSceneNode*)selected)->getMesh()->setMaterialFlag(video::E_MATERIAL_FLAG::EMF_WIREFRAME, false);
 
    selected = pointedNode;
    if (selected != 0)
        ((scene::IMeshSceneNode*)selected)->getMesh()->setMaterialFlag(video::E_MATERIAL_FLAG::EMF_WIREFRAME, true);
}
 

It is notable that this code does function unless the user tries to deselect a currently selected node by right-clicking in an arbitrary direction.

-Will

[CuteAlien]

Check the type of the node you get. Probably it's not a IMeshSceneNode - my guess would be that you hit the skybox.

[cat.exe]

Hmm... this is a good suggestion, but I need to know: Could there possibly be a skybox by default in my irr scene? I did not insert one myself (Nor have I ever used one before.)

[CuteAlien]

Irrlicht doesn't add a skybox. If you created your scene with an editor like irrEdit... I have no idea (never used it). But just take a look at the variable in the debugger after it crashed - then you will know within seconds what type of node that really is. That's why we have debuggers :-)

[cat.exe]

Fixed! The problem did turn out to be related to what type the returned object was (Thanks again, CuteAlien) though I'm still not sure the exact cause. The point is, I fixed it by removing the cast to scene::IMeshSceneNode* and simply called scene::ISceneNode::setMaterialFlag() rather than scene::IMeshSceneNode::getMesh() first. This was the better way to do it in the first place, rather than taking that extra step that seemed to break it. Finished code:

Code: Select all

if (receiver->rightMouseButtonPressed())
{
    scene::ISceneNode* pointedNode = smgr->getSceneCollisionManager()->getSceneNodeFromCameraBB(camera, -1);
 
    if (selected != 0)
        selected->setMaterialFlag(video::E_MATERIAL_FLAG::EMF_WIREFRAME, false);
 
    selected = pointedNode;
    if (selected != 0)
        selected->setMaterialFlag(video::E_MATERIAL_FLAG::EMF_WIREFRAME, true);
}

Thanks!

-Will

[cat.exe]

Irrlicht doesn't add a skybox. If you created your scene with an editor like irrEdit... I have no idea (never used it). But just take a look at the variable in the debugger after it crashed - then you will know within seconds what type of node that really is. That's why we have debuggers

In reply to this:

No, I do not use a scene editor (and I am now absolutely sure my program is 100% skybox free )

I looked at the debugger type and it simply said ISceneNode (which is the pointer type, but it still could be a subclass such as IMeshSceneNode).

Thanks!

[CuteAlien]

The debugger usually knows the real type of objects and shows that (even after casting). But then again you usually never have just an ISceneNode - confusing. When you are lucky (and compiling in debug) the base-class (IReferenceCounted) might have set the debug name set which you can check with getDebugName ().

[Seven]

http://irrlicht.sourceforge.net/forum// ... light=pick