Re: [info-performer] performer shading language

From: Terry Welsh (mogumbo++at++gmail.com)
Date: 06/29/2005 06:45:07

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Hmmm. I can't see any huge problem there. It looks like you might be
using the negative incident vector, though. Try adding this minus
sign to your vertex shader.

vViewVec = normalize(-worldPos.xyz);

-- 
Terry Welsh - mogumbo 'at' gmail.com
www.reallyslick.com  |  www.infiscape.com  |  www.vrsource.org
>  From: Bambang Veriansyah <vaveri++at++yahoo.com>
>  Date: Tue, 28 Jun 2005 17:48:34 -0700 (PDT)
>  Subject: Re: [info-performer] performer shading language
> 
> 
> Thanks Terry,
> 
> I modified my fragment shader as your suggestion,
> 
> Here is the my fragment shader:
> 
>    vec4 reflVec;
>    reflVec.xyz = reflect(vViewVec, vNormal);
>    reflVec     = ViewMatrix_inverse * reflVec;
>    vec4 refl   = textureCube(envMap, reflVec.xyz);
>    gl_FragColor =  refl;
> 
> 
> When I change the eye direction, the reflection is
> correct.But if I change the eye position, the
> reflection still not correct.
> Do I miss something ? Should I send the eye position
> to the shader?
> 
> Thanks in advanced.
> 
> 
> ==================================================
> Terry Welsh wrote:
> 
> It looks like you need to transform reflVec from view
> space to world space before you use it to access your
> cube map.  To do this, you can pass the inverse view
> matrix to your shader as a uniform and multiply
> reflVec by it.  In fact, you only really need the
> upper-left 3x3 of that matrix, since translation
> doesn't matter in this case.
>

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