How do I use OpenGL 3.x VBOs to render a dynamic world?

Question

Although there seem to be very few up to date references for OpenGL 3.x itself, the actual low level manipulation of OpenGL is relatively straight forward. However I am havi

Answer 1

If your entire world is truly dynamic, you can use the GL_STREAM_DRAW_ARB usage flag and reset the data on each frame. Don't bother manipulating it, just try to stream as efficient as possible.

However, I assume that you have a scene that consists of multiple rigid objects that move relative to each other. In this case, use one VBO for each object and specify the GL_STATIC_DRAW_ARB usage flag. You can then set the modelview transform for each instance of an object and render them using one draw call per instance.

A rule of thumb (on the PC) is to issue not more than one draw call per MHz of your CPU. This is a crude estimate, but there's some truth to it. Don't worry about putting multiple independent objects into a single VBO or other performance tricks if you stay below this limit.