Error on loading and using Ogre::TexturePtr

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robert_sasu
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Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Wed Dec 19, 2012 4:14 pm

I am trying to load a texture from resources and I get an error of Object reference not set to an instance of an object on the line 12 (from the pasted code). The strange thing is that the loading part goes well, nothing in log (I am using ogreLogLevel=High) and on that line where I am writing if the resources exists or not I get TRUE for the 2 textures I am trying to open.

I might miss out something, but I do not have any idea what. I need a little help here :)

Code: Select all

	void DataManager::addTextures(const Ogre::String& destinationTextureName, const Ogre::String& sourceTextureName, const Ogre::String& outputFileName)
	{
		Ogre::ResourceGroupManager::getSingletonPtr()->loadResourceGroup(SKYX_RESOURCE_GROUP);
		TraceWriteLine("EXISTS {0} {1}",Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,destinationTextureName),
			                            Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,sourceTextureName));
		Ogre::TextureManager *textureManager = Ogre::TextureManager::getSingletonPtr();
		assert(textureManager != NULL);

		const Ogre::TexturePtr& destinationTexture = textureManager->getByName(destinationTextureName, SKYX_RESOURCE_GROUP);
		const Ogre::TexturePtr& sourceTexture = textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP);

		Ogre::HardwarePixelBufferSharedPtr destinationBuffer = destinationTexture->getBuffer(0,0);
		Ogre::HardwarePixelBufferSharedPtr sourceBuffer = sourceTexture->getBuffer(0,0);

Thanks,

Robert
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Wed Dec 19, 2012 7:42 pm

A sneaky bug in your code:

Code: Select all

      const Ogre::TexturePtr& destinationTexture = textureManager->getByName(destinationTextureName, SKYX_RESOURCE_GROUP);
      const Ogre::TexturePtr& sourceTexture = textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP);
and the fix is simple:

Code: Select all

      const Ogre::TexturePtr destinationTexture = textureManager->getByName(destinationTextureName, SKYX_RESOURCE_GROUP);
      const Ogre::TexturePtr sourceTexture = textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP);
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 12:24 pm

That change does not resolve my problem, I also tried to use just Ogre::TexturePtr, without const, but the same error happens every time.
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Thu Dec 20, 2012 1:27 pm

Looks like I was wrong. A const reference to a pure rvalue is okay, it just looks suspicious and I usually don't see code like that. So the problem is something else.
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 1:40 pm

It is just a few line code here, and I do not see where is the error, as the resource truly exists. And this would really help me to optimize a big part of the code, and I need to load those textures (there are just .dds files saved earlier, and needed to be loaded). I just generated them, and need some modifications, so normally this code will not rule, it is just for creating the textures.
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Thu Dec 20, 2012 2:26 pm

I guess you'll have to step through that and see where and why the reference loses its object instance.
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robert_sasu
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 2:40 pm

Is there any way to load a texture known by name and resource_group to a Ogre::TexturePtr ?
I do not see how could the object loses its intance between 2 line.

The problem is that the texture loaded by textureManager->getByName(destinationTextureName, SKYX_RESOURCE_GROUP) is NULL. But the resource exists, and on that line I get TRUE for existing resource. But I do not see why I can't load that texture. I am surely missing something, but I do not have any idea.
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Thu Dec 20, 2012 2:50 pm

There's a lot happening after the two lines, inside the getBuffer() call for e.g.
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 3:00 pm

When using the code like this:

Code: Select all

		Ogre::ResourceGroupManager::getSingletonPtr()->loadResourceGroup(SKYX_RESOURCE_GROUP);
		TraceWriteLine("EXISTS {0} {1}",Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,destinationTextureName),
			                            Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,sourceTextureName));

		Ogre::TextureManager *textureManager = Ogre::TextureManager::getSingletonPtr();
		assert(textureManager != NULL);

		const Ogre::TexturePtr sourceTexture = textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP);
		if (textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP).isNull()) TraceWriteLine("SOURCE IS NULL");
I get in the output log file that SOURCE IS NULL, even if that it exists as I get TRUE TRUE on the 2nd line. So it's normal that when calling any method from sourceTexture it will fail, because of not an instance of an Object.
So the problem is that I can't load the resource, while the resource exists. Is there any other method for this ? Or am I missing something ?
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Thu Dec 20, 2012 3:24 pm

Hmm.. what if the resource exists but Ogre thinks it's not a texture?
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 3:29 pm

The resource was saved using this code:

Code: Select all

		Ogre::Image image;
		mVolTextures[0]->convertToImage(image);
		image.save(filename);
Where mVolTextures is Ogre::TexturePtr mVolTextures[2];
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Re: Error on loading and using Ogre::TexturePtr

Post by bstone » Thu Dec 20, 2012 3:34 pm

And what codec saves the .dds files? Ogre's DDS codec is only for loading them and doesn't support encoding. Can you open them with some other tools to see if they are correct?
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Thu Dec 20, 2012 3:39 pm

Yes, I can open them with any .dds viewer, and they are correct.
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Re: Error on loading and using Ogre::TexturePtr

Post by Kojack » Fri Dec 21, 2012 2:15 pm

robert_sasu wrote:When using the code like this:

Code: Select all

		Ogre::ResourceGroupManager::getSingletonPtr()->loadResourceGroup(SKYX_RESOURCE_GROUP);
		TraceWriteLine("EXISTS {0} {1}",Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,destinationTextureName),
			                            Ogre::ResourceGroupManager::getSingletonPtr()->resourceExists(SKYX_RESOURCE_GROUP,sourceTextureName));

		Ogre::TextureManager *textureManager = Ogre::TextureManager::getSingletonPtr();
		assert(textureManager != NULL);

		const Ogre::TexturePtr sourceTexture = textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP);
		if (textureManager->getByName(sourceTextureName, SKYX_RESOURCE_GROUP).isNull()) TraceWriteLine("SOURCE IS NULL");
I get in the output log file that SOURCE IS NULL, even if that it exists as I get TRUE TRUE on the 2nd line. So it's normal that when calling any method from sourceTexture it will fail, because of not an instance of an Object.
So the problem is that I can't load the resource, while the resource exists. Is there any other method for this ? Or am I missing something ?
loadResourceGroup will only load known resources. These are things added automatically by scripts, or manually declared resources. Meshes, skeletons and textures are not known (and will not be loaded by loadResourceGroup) unless declared with ResourceGroupManager::declareResource first (and then the group is initialised), or when you first try to use them (creating an entity with a mesh file works because ogre searches the resource paths for the file if it's not already in the mesh manager).
If you haven't declared those textures, they weren't loaded by the first line.

So why are they shown as true in the second line? Because resourceExists has three steps: 1 - do a case sensitive search of the resource manager. 2 - if that failed, do a case insensitive search. 3 - if both failed, search the hard drive in the resource group's registered paths.
Your files aren't declared or loaded, so they fail the first two checks, but the third succeeds because they do exist on disk.

TextureManager::getByName doesn't go that far, it purely looks at the list of known resources (could be loaded, unloaded, etc, as long as they were declared). So it can't see that the textures are on disk.

You could load them manually into Images (using Image::load) then create a texture from them with TextureManager::loadImage.
Or if they are known at the beginning you could declare them in the ResourceGroupManager so they will be known after initialiseResourceGroup is called (note: each resource group can only be declared once, there's a flag to block later calls. So you can't init the group, then later declare more stuff in it and init again.
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Re: Error on loading and using Ogre::TexturePtr

Post by scrawl » Fri Dec 21, 2012 4:11 pm

Nice answer, Kojack.

I believe that calling TextureManager::load with the texture name should also fix the problem.
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Re: Error on loading and using Ogre::TexturePtr

Post by Kojack » Fri Dec 21, 2012 4:40 pm

I was going to say that, but while checking the code I thought I saw that it wouldn't work. If a texture isn't known, load will call createOrRetrieve which will create a new empty texture resource of the name given. But what I didn't pay attention to is that the next step of the load method is to load the resource it just created (it was created as unloaded), so it then finds the one on disk with the same name and group and loads that.

So yep, scrawl's solution is better. :)
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Re: Error on loading and using Ogre::TexturePtr

Post by robert_sasu » Sat Dec 22, 2012 6:19 pm

Thank you for your help :) I am in holiday and I will try your methods after 7th of January :)
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Re: Error on loading and using Ogre::TexturePtr

Post by formula123 » Wed Mar 18, 2015 9:50 am

Nice shot! Solve my problem. Thank you, Kojack.
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