Segfault when trying to create multiple scene nodes.

[doesntmatterwho]

I'm following the tutorials on the ogre wiki. I have an example, where I want to spawn more meshes but somehow it gives me failed assertion. The code is :

Code: Select all

#include "TutorialApplication.h"
#include "functions.h"
#include <stdlib.h>
//-------------------------------------------------------------------------------------
TutorialApplication::TutorialApplication(void)
{
}
//-------------------------------------------------------------------------------------
TutorialApplication::~TutorialApplication(void)
{
}

//-------------------------------------------------------------------------------------
void TutorialApplication::createScene(void)
{
    mSceneMgr->setAmbientLight(Ogre::ColourValue(0, 0, 0));
    mSceneMgr->setShadowTechnique(Ogre::SHADOWTYPE_STENCIL_ADDITIVE);
 
    Ogre::Entity* entNinja = mSceneMgr->createEntity("Ninja", "ninja.mesh");
    entNinja->setCastShadows(true);
    mSceneMgr->getRootSceneNode()->createChildSceneNode()->attachObject(entNinja);
 
    Ogre::Plane plane(Ogre::Vector3::UNIT_Y, 0);
 
    Ogre::MeshManager::getSingleton().createPlane("ground", Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME,
        plane, 1500, 1500, 20, 20, true, 1, 5, 5, Ogre::Vector3::UNIT_Z);
	

        //THIS IS WHERE I WANT TO SPAWN MULTIPLE MESHES
	Ogre::Entity* entGround = 0;
	for (int i = 0 ; i <10; i++ ) { 
		entGround = mSceneMgr->createEntity(toString(i), "ground");
		mSceneMgr->getRootSceneNode()->createChildSceneNode()->attachObject(entGround);
	}
    
 
    entGround->setMaterialName("Examples/Rockwall");
    entGround->setCastShadows(false);
 
    Ogre::Light* pointLight = mSceneMgr->createLight("pointLight");
    pointLight->setType(Ogre::Light::LT_POINT);
    pointLight->setPosition(Ogre::Vector3(0, 150, 250));
 
    pointLight->setDiffuseColour(1.0, 0.0, 0.0);
    pointLight->setSpecularColour(1.0, 0.0, 0.0);
 
    Ogre::Light* directionalLight = mSceneMgr->createLight("directionalLight");
    directionalLight->setType(Ogre::Light::LT_DIRECTIONAL);
    directionalLight->setDiffuseColour(Ogre::ColourValue(.25, .25, 0));
    directionalLight->setSpecularColour(Ogre::ColourValue(.25, .25, 0));
 
    directionalLight->setDirection(Ogre::Vector3( 0, -1, 1 )); 
 
    Ogre::Light* spotLight = mSceneMgr->createLight("spotLight");
    spotLight->setType(Ogre::Light::LT_SPOTLIGHT);
    spotLight->setDiffuseColour(0, 0, 1.0);
    spotLight->setSpecularColour(0, 0, 1.0);
 
    spotLight->setDirection(-1, -1, 0);
    spotLight->setPosition(Ogre::Vector3(300, 300, 0));
 
    spotLight->setSpotlightRange(Ogre::Degree(35), Ogre::Degree(50));
}

The error message is this:




Can anybody tell me what am I doing wrong or how can I spawn multiple meshes the correct way?

[spacegaier]

In which lines does the crash occur? I assume in the for-loop?

[doesntmatterwho]

For sure the loop is causing the error, because when not using loop everything works fine. I'm not sure where the error itself comes from - from the loop or from later rendering code. The exact line causing the error is this:

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entGround = mSceneMgr->createEntity(toString(i), "ground");

[c6burns]

Step through the program in the debugger. You might learn the situation is different than assumed.

[doesntmatterwho]

The code is so simple that there is no need for the debuger.

[Mind Calamity]

This is a bug in OGRE with prefabs, they all crash on render, I'm not sure what's up with that, I'll make a report.

[Mind Calamity]

Okay, I just found out why it crashes, the MaterialPtr in the entity is null, and so it crashes, to fix this, move these 2 lines inside the loop:

Code: Select all

    entGround->setMaterialName("Examples/Rockwall");
    entGround->setCastShadows(false);

It should be assigned a default material, but it's not for some reason.

Reported the issue here: https://ogre3d.atlassian.net/browse/OGRE-467

[c6burns]

The code is so simple that there is no need for the debuger.

Ignorance is bliss

[Mind Calamity]

Personally, I've learned the hard way that there's no code issue where a debugger would not be helpful/needed, except maybe memory corruptions, those suckers are hard to track, and a debugger sure as hell doesn't help.

[c6burns]

I agree there is nothing too simple for at least a sanity check in the debugger. It should be every programmer's kneejerk reaction, especially when the app segvs. Yes, in this case it's an issue in Ogre (though why you would want 10 planes with no material, I don't know ... nevertheless crashing is bad and Ogre should at least assert somewhere instead of crash).

Re: corruption, gdb has a feature where you can break on read or write to a given address. I assume visual studio has the same feature, just I haven't had to use it there yet. That can reaaaaaaaally help with memory issues

[Kojack]

Re: corruption, gdb has a feature where you can break on read or write to a given address. I assume visual studio has the same feature, just I haven't had to use it there yet. That can reaaaaaaaally help with memory issues

Yep, in VS it's called a data breakpoint. You can monitor a block of any size of bytes at any address for changes. I don't know of breaking on read though.

[doesntmatterwho]

Thank you.