I'm learning OpenGL and there is something I don't understand regarding model loading.
Lets say I found a free .blend model of a tree. The problem is - currently in my program all models have only one texture. But this model use two textures, one for trunk and another for branches and leaves. Actually trunk and leaves are two separated models on one scene.
What to do in this situation? Editing model manually could take a long time (I'm not an expert in Blender). I could join two textures in one and correct UV's automatically. But most likely a lot of space will be wasted on such an automatically created texture. I could also modify my model format (it's more like memory dump + header actually) so I could store N models with N textures as one object. But using N times more VBOs and textures when you actually need only one is inefficient.
I'm wondering maybe there is a well known tool for automatically joining multiple objects in one? Or maybe some good practice for this case? Or something like this.