Since according to the newsletter Stuart's current ongoing quest is to get
better performance for 3d clouds, here are some of my observation:

* I've noticed that when I use the relatively lowres Altocumulus texture
sheet (3x3 on one sheet) I can basically use a ridiculous number of
sprites without performance deterioration, whereas when I use the hires
Cumulus sheets (1x2 plus 1x3) the number of sprites I can show before
performance takes a nosedive goes down substantially.

The high resolution is however only needed for the small amount of clouds
which are relatively close, but what makes a real difference is the amount
of distant clouds, because there are so much more. So my guess is that
using lowres textures for distant clouds would do just fine and improve
performance. I've been wondering if dds sheets with the mipmaps would not
automatically address that problem.

The other option to test would be to scale down the resolution of the Cu
cloud textures and see if the result is still acceptable (I know it isn't
perfect, there was a reason I went to high resolution in the first place,
but maybe the flaws can be hidden by the right mixture with other texture

* There seems still to be stuff computed in the shaders per vertex that is
actually an uniform per frame - eyepos for instance. I wonder if the
computations could be speeded up significantly  by consequently pulling
all things that are really uniforms out of the shaders.

* We're likewise fond of computing stuff per frame that changes more like
per minute. The orientation of faraway clouds doesn't have to be computed
per frame, because it can't change much per frame. If there'd be a way to
store the value used last time, then (based on a distance criterion), one
could assign clouds into n task groups and recompute a task group only
every nth frame and use the last stored value otherwise. Back when I
rotated clouds from Nasal, this did work and improved performance by a
factor 5 or 6 - not sure how much it could do with a Shader setup, not
sure how to do it technically, but my guess is that it would speed things

Maybe some of this helps!


* Thorsten

All the data continuously generated in your IT infrastructure 
contains a definitive record of customers, application performance, 
security threats, fraudulent activity, and more. Splunk takes this 
data and makes sense of it. IT sense. And common sense.
Flightgear-devel mailing list

Reply via email to