Well, you could use pixel buffer object, but if you’re on an old machine, there is nothing what would come to my mind. Try using TextureSubImage, it is a bit faster.
Of course you should just upload the bounding rectangle of the reigon that changed instead of the whole texture. But you can’t expect to change the texture without uploading anything
You’re right, I never thought about it that way. Its just that in my software, the texture is changing dynamically based on any type of transformation I apply, so a have to upload a new texture many times.
I was just thinking last night that for my situation it would be really convinient if GL would let me manipulate texture memory directly.
But it seems TexSubImage2D will be an improvement.