Hi guys,
About the performance i guessed it was not free, but i did not have an
idea about the cost, so i made a little test in my application, I hacked
shadowmap.cpp to render the shadowmap only on node with the nodemask
receiveShadow then other are renderer as if they were outside the
shadowscene
The first scene:
Hacked shadowmap
- the earth model - receive shadow
- 100 * dumptruck - cast shadow but does not receive
result = 63fps
No hacked Version:
- the earth model - receive shadow
- 100 * dumptruck - cast shadow and receiveshadow
result = 38fps
The second scene:
Hacked shadowmap
- the earth model - receive shadow
- 100 * cow - cast shadow but does not receive
result = 82fps
The second test was with regular shadowmap implementation so:
No hacked Version:
- the earth model - receive shadow
- 100 * cow - cast shadow and receiveshadow
result = 102fps
the test was on GeForce 8600M GT - 512 MB - dual core 2 2.4Ghz
Then it's just mean that it's not so free if you have a lot of object
shadowed. It's a quick test so maybe it's not accurate
but it think it gives an idea. But the other argument to control the
self shadowing feature it's to just to control if you
want to see shadow or not on object. Sometime in non realistic rendering
or special rendering you want to control
what cast and receive shadow. But i know it's not most of usage so i
understand ShadowMap is not designed for that.
Any way it was interesting to understand the current ShadowMap
implementation.
Is there a version of the futur ShadowMapStandard available on the web ?
Cheers
Cedric
Jean-Sébastien Guay wrote:
Hello Cedric,
With this solution an object that cast shadow will get it's own
shadow isn't it , i know in most of the case it's what
you want but i would like to avoid when i can for performance reason.
I would like something like a list a of caster and a list of
receiver. Maybe i could just write a shadowmap
technic that allow that.
The osgShadow::ShadowMap technique has just not been designed to do
that. You have the option of either:
1. Casts and receives : object is under ShadowedScene, and has the
correct nodemasks
2. Does not cast but receives : object is under ShadowedScene, and has
~CastsShadow nodemask
3. Does not cast, does not receive : object is not under ShadowedScene.
Doing anything more would require some changes. You can always
subclass ShadowMap to do it, but as the class stands it's not very
useful since you'll need to copy-paste most of it anyways because it
was not really designed to be subclassed (all the work is done in the
cull() method). I think the upcoming improvements by Wojtek will make
this sort of thing much more doable.
But in any case, I don't really see why you don't want an object to
self-shadow. In a shadow map technique, it does not involve any
additional cost. If the object casts shadows on other objects, then
it's already part of the ShadowMap RTT, and thus, where it casts its
shadows has no effect on performance (at least as far as I know,
perhaps I'll learn something new...).
Hope this helps,
J-S
--
+33 (0) 6 63 20 03 56 Cedric Pinson mailto:[EMAIL PROTECTED]
http://www.plopbyte.net
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