It might be interesting to see what happens if you convert the DB to .ive
using osgconv.

> Q1) Does anybody know the advantages/disadvantages of using VBO, vertex
> arrays, or display lists for drawables?  Since vertex arrays seem to page
> in
> faster, I am considering using them.

Of the three, vertex arrays is the only one that (typically) doesn't
involve data copies over the system bus at creation time, which is
probably why it reduces your tile load time.

All are designed to reduce the number of function calls. The info that
follows is implementation dependent...

Display lists -- OpenGL 1.0 and later.
  Pro: Potentially the fastest draw time.
  Con: Static (no editing allowed); can be expensive to create.

Vertex Arrays -- OpenGL 1.1 and later.
  Pro: Allows for dynamic data and fast editing.
  Con: By spec, data is stored in client RAM and therefore incurs a
system-bus copy at render time.

Buffer objects -- OpenGL 2.5 and later.
  Pro: Data is typically stored on the graphics card to speed rendering.
  Con: Editing data requires "mapping" the buffer back to host memory,
usually implemented as a copy over the system bus.

> Thanks, I wish I could email you a beer.

I think I owe Chris a beer too. I've lost track of the number of pints I
owe Robert.
   -Paul


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