From: Allan Schaffer (allan++at++sgi.com)
Date: 03/20/2000 13:31:43
On Mar 19, 7:59pm, Simon Hayhurst wrote:
> From some work we did a few years ago in SGI Europe, we also found a huge
> gain by only using hemi-spheres, and rotating the hemi-sphere to face the
> user. There's a fair bit of App side workload in doing this, but since
> molecules are typically moving anyway, the net win was considerable.
Yes this would be a tremendous gain. Place the hemisphere geometry
under pfBillboard nodes so that they'll automatically rotate to face
the viewer.
Someone might be thinking, "what's the difference, why not just let
automatic backface culling remove the back-facing side of the
spheres?": It's because the backface calculations are done on a
per-triangle basis down in the graphics pipe. Not sending the
geometry down in the first place would be a big performance win.
And on MP systems, the billboard calculation is done in the CULL,
where there's quite typically plenty of extra time each frame.
Allan
-- Allan Schaffer allan++at++sgi.com Silicon Graphics http://reality.sgi.com/allan
This archive was generated by hypermail 2b29 : Mon Mar 20 2000 - 13:32:30 PST