OK, I understand that gl_quads are deprecated, and thus we're not 'supposed' to use them anymore. I also understand that a modern PC when running a game using gl_quads is actually drawing two triangles.
Now, I've heard because of that a game should be written using triangles instead. But I'm wondering if, due to the specifics of how OpenGL makes that quad into two triangles, it is ever advantageous to use quads still?
Specifically, I'm currently rendering many unconnected quads from rather large buffer objects. One of the areas I have to be careful is how large the vector of floats I'm using to make/update these buffer objects get (I have quite a few extra float values per vertex, and a lot of vertices in a buffer - the largest buffers are about 500KB).
So it strikes me that if I change my buffer objects to draw triangles this vertex data is going to be 50% larger (six vertices to draw a square rather than 4), and take 50% longer for the CPU to generate.
If gl_quads still work, am I getting a benefit here, or is the 50% extra memory and CPU time still being used on OpenGL's automatic conversion to two triangles?