Hi Robert,
Yes, I agree the environment variable is not a very good way of switching
this on.
I'm afraid I can't add much info about this problem as the fix was really
just a bit of a 'leap' from J-S's comment.
If it is a bug in the ATI driver I guess we could argue that OSG need not
provide a workaround, but anything that might get end-users going without
suggesting they get a better graphics card, seems worth while. On the other
hand, I guess none of us would like to see OSG drowning in workarounds for
wierd video driver problems ;-)
BTW. If it helps, the machine that I get this problem has an ATI Radeon X300
with fully up-to-date drivers (Date 31/07/2008 version 8.522.0.0).
I'm not too bothered if this doesn't go in as it is. I suspected it might
need some more work, but at least I have drawn attention to the problem and
to help anyone that needs a workaround.
Cheers.
Chris.
----- Original Message -----
From: "Robert Osfield" <[EMAIL PROTECTED]>
To: "Chris Denham" <[EMAIL PROTECTED]>; "OpenSceneGraph Submissions"
<[email protected]>
Sent: Thursday, September 18, 2008 1:46 PM
Subject: Re: [osg-submissions] Fix to allow ShadowMap to work on some ATI
drivers.
Hi Chris,
I have reviewed your changes but don't feel that an env var is the
best way to tackle this particular problem. I'm not sure of the best
way to enable this workaround, so will need to learn more about the
this issue, and how widely it could affect OSG effects/techniques like
as ShadowMapping - it sounds like ShadowMapping might be jut one place
where issues could arise.
The reversing of the t direction on ATI seems rather an odd problem,
do you know if this a confirmed bug?
J-S could you explain what made you suggest this in the first place?
On a side note, I have merged the addition of the polyOffset copying
in the copy constructor.
Robert.
On Mon, Sep 15, 2008 at 4:12 PM, Chris Denham <[EMAIL PROTECTED]> wrote:
I found a reference on the lists about this problem which I was
experiencing.
i.e. ShadowMap not working on some ATI cards.
Re: [osg-users] simple shadows
Jean-Sébastien Guay
Mon, 05 May 2008 08:33:27 -0700
http://www.mail-archive.com/[EMAIL PROTECTED]/msg10268.html
In this message, Jean-Sébastien suggested that reversing t-direction of
texgen running on ATI might mix it.
Prompted by this, I have added support an environment variable that allows
reversal of the t-direction.
I have attached a modified version of OSG2.6 ShadowMap.cpp that includes
this change.
Basically it behaves exactly as before except when environment variable
OSG_REVERSE_T_DIRECTION=YES
In this case, the y direction of the transform applied to the textgen is
reversed.
Works for me! (thanks for the tip Jean-Sébastien).
Oh.... and by the way, not relevant to this particular problem, but I also
added the missing copy of polyOffset to the copy constructor of ShadowMap.
Sorry for mixing this in here ;-).
Cheers.
Chris Denham.
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