Hi Ramy,
Teoretically LispSM uses one extra pass to render shadow map. However,
optimal shadow volume computation requires some extra work. Default LispSM
uses DrawBounds to compute shadow volume, which means it does extra
pererender to compute box around pixels in prerenderd map. You may check
alternative CullBounds variant. IT may offer better performance if you have
small number of drawables, (number of tris per drawable does not matter
here). Or simplest of the pack ViewBounds which simply computes volume by
checking main camera view frustum. Depending on type of application last
method may produce similar results to former more complicated ones. There is
a catch though. ViewBounds method has a bug which basically ignores
MinimalLightMargin parameter. I have made a fix for this but it was not yet
submitted, because its in the pack with TrapezoidalShadowMap which is still
in work.
Maybe I can will split them and send separately, if you are interested.
Don't bet on Trapezoidal, it will have the same performance as LispSM. It
really resemble LisPSM but may have some better quality for low level moving
viewer (person or driver).
Wojtek
-----Original Message-----
From: Ramy Gowigati
Sent: Thursday, November 04, 2010 5:09 PM
To: osg-users@lists.openscenegraph.org
Subject: Re: [osg-users] does LiSPSM cull the objects in the scene?
Thanks for your answer :) I knew you were going to reply :-D
Thanks for your advise, those are the values I am playing with. I was also
tried to give the ShadowScene the objects I want to cast shadows (by
applying the castShadowMask on selected objects). that actually worked, but
performance was still slow.
The problem appears to be that our scene is too big and too complex (in
terms of tri count). I believe that's where the problem is, scene has a very
large tri count and the shadow almost doubles it which is an overkill for
the GPU. So I will look into trying to simplify the scene then having
another go.
Are there any shadowing techniques that can help? Or is LiSPSM the best in
my case?
thanks
ramy
------------------
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http://forum.openscenegraph.org/viewtopic.php?p=33460#33460
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