Hi David,

I don't think there is a way to read the GL_FOG ON/OFF attribute from within
the shader?  I have the orange book, but it doesn't have any built-in
functions or uniforms for getting the state of GL_FOG ON/OFF.


Zach

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of David Guthrie
Sent: Friday, November 10, 2006 09:26
To: osg users
Subject: Re: [osg-users] glsl shader ON/OFF

Since you can read the GL_FOG parameters in the shader, why not just read
the attribute and don't calculate fog in the shader.  That's pretty
analogous to setting a uniform.

David

On Nov 9, 2006, at 6:13 PM, Robert Osfield wrote:

> Hi Zach,
>
> On 11/9/06, Zach Deedler <[EMAIL PROTECTED]> wrote:
>> Hello,
>>
>> Easy question.
>>
>> I have a fog shader, and I want to disable it sometimes.
>> stateSet->setMode(GL_FOG, osg::StateAttribute::OFF) in a shader?
>
> Fixed function pipeline is sweet for many things... shaders well make 
> the above rather more awkward...
>
>> Whats optimal?
>> 1) remove the program from the stateset? or
>> 2) set the program mode to OFF? or
>> 3) add a bool on/off uniform to the shader?
>> 4) Attach a switch node to the state set?
>
> Switching StateSet to use different programs, or using a uniform value 
> to switch the shader path on/off would be my favorite solutions.
>
> Robert.
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>

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