Hi all, thanks in advance for the answers.
My question is where glTexImage2D loading the image?
because if I make a simple program with a window and with all the code in one file a link to this memory function, instead
if I am using 2 windows made ​​sdl and move the stuff of texture transform it into a class and put it into another file does not work anymore?
It may also depend on the mode multi-thread in Visual Studio?

PS: sorry for my english.