Material problems

[kohansey]

Hello everyone,

I am still relatively new to Irrlicht and need some help working with materials. I created a custom scene node, and I have been successful in getting the scene node to display a loaded 3DS mesh. Now I want to add texture to the mesh, and following the examples I need to do something like this

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this->setMaterialTexture(0, SceneManager->getVideoDriver()->getTexture("data\\Planetgas0-cl.bmp")); 
// set diffuse texture
this->setMaterialFlag(video::EMF_LIGHTING, true); // enable dynamic lighting
this->getMaterial(0).Shininess = 20.0f; 

However, when I get to this->getMaterial(0).Shininess = 20.0f, the program crashes, and the debugger spits out:

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First-chance exception at 0x00409e99 in GameEngine.exe: 0xC0000005: Access violation writing location 0x00000014.
Unhandled exception at 0x00409e99 in GameEngine.exe: 0xC0000005: Access violation writing location 0x00000014.

Does this have to do with the fact I am creating a custom scene node?
Could someone please give me some direction?

[hybrid]

Maybe you didn't override getMaterial, hence it returns a Nullpointer.

[kohansey]

yes, that is correct. I didn't override the getMaterial function. Is this a requirement to get textures to work for custom scene nodes? Is the scene node responsible for handling the materials of the meshes? How would one go about doing this? Is there anything else that I would need to override?

I took a look at AnimatedMeshSceneNode, and it uses a core::array of SMaterials. I am confused about this, I thought that the Material was specific to the mesh not the node, how does the node know which material to render for any given mesh?

[kohansey]

I guess the real question is, what does setMaterialTexture do if my custom scene node contains the SMaterial?

[vitek]

Look at the code and see what it does...

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		void setMaterialTexture(u32 textureLayer, video::ITexture* texture)
		{
			if (textureLayer >= video::MATERIAL_MAX_TEXTURES)
				return;

			for (u32 i=0; i<getMaterialCount(); ++i)
				getMaterial(i).setTexture(textureLayer, texture);
		}

What happens if getMaterialCount() returns 0 or getMaterial() doesn't return the material?

Travis

[hybrid]

A custom scene node must override the getMaterial method. Due to some (bad?) design decisions from the past, the method is not pure virtual, so the compiler doesn't require you to override it. But in that case a casted Null will be returned.