Textures

OpenGL OpenGL: Basic Coding
1

I need help with textures. The last parameter to glTexImage2D(), a pointer to the image data - this data is copied to the texture, right? Or IS this the texture data? I thought that texture data is in video memory. So the data passed to glTexImage2D() is only copied?
So, do I HAVE TO pass a pointer or can I pass just NULL when I copy other data to the texture with glTexSubImage2D() later on?

2

The data is copied from the pointer address. If you pass NULL in, there will be no update of the texture.

3

Thanks.