How many VBOs do I use?

Question

So I understand how to use a Vertex Buffer Object, and that it offers a large performance increase over immediate mode drawing. I will be drawing a lot of 2D quads (sprites), and I am wanting to know if I am supposed to create a VBO for each one, or create one VBO to hold all of the data?

Answer 1

You shouldn't use a new VBO for each sprite/quad. So putting them all in a single VBO would be the better solution in your case.

But in general i don't think this can be answered in one sentence.

Creating a new VBO for each Quad won't give you a real performance increase. If you do so, a lot of time will be wasted with glBindBuffer calls for switching the VBOs. However if you create VBOs that hold too much data you can run into other problems.

Small VBOs:

• Are often easier to handle in your program code. You can use a new VBO for each Object you render. This way you can manage your objects very easy in your world
• If VBOs are too small (only a few triangles) you don't gain much benefit. A lot of time will be lost with switching buffers (and maybe switching shaders/textures) between buffers

Large VBOs:

• You can render tons of objects with a single drawArrays() call for best performance.
• Depending on your data its possible that you create overhead for managing a lot of objects in a single VBO (what if you want to move one of these objects and rotate another object?).
• If your VBOs are too large its possible that they can't be moved into VRAM

The following links can help you:

Vertex Specification Best Practices

Answer 2

Use one (or a small number of) VBO(s) to hold all/most of your geometry.

Generally the fewer API calls it takes to render your scene, the better.