Ok. A tip: if you use FBOViewport you can write depth and color texture 
in the same pass, without any copying. That might help a bit. :)

(However, I can't remember if FBOvp supports mipmap generation at the 
moment. It ought to quite easy to add though.)

Cheers,
/Marcus

Stefano wrote:
> Well, it requires at least 3 additional rendering passes: the grab of the
> depth buffer, the grab of the color buffer and a polygonforeground with a
> shader to render the result. The thing that probabily slows down the 
> most is
> the real-time mipmapping that opengl has to perform to the color 
> buffer in
> each frame.. furthermore, if you also want to blur/mipmap the depth 
> buffer
> to increase the accuracy of the effect, well.. things start to be a 
> little
> slower :) but I think it's worth a try.
>
> 2007/5/9, Marcus Lindblom <[EMAIL PROTECTED]>:
>>
>> Neat!
>>
>> Do you know how much performance impact does your technique have? I'm
>> thinking of implementing something similar to blur objects close to the
>> camera in our app (someday at least.. :)
>>
>> Cheers,
>> /Marcus
>>
>> Stefano wrote:
>> > I solved the problem, at last. The render had almost all the depth
>> values
>> > compressed in a very limited range due to the non linearity of the 
>> depth
>> > buffer. Once i I linearized that buffer using the following piece of
>> code
>> > into a vertex shader the problem disappeared.
>> >
>> > vec4 xx = gl_ModelViewProjectionMatrix * gl_Vertex;
>> > xx.z = xx[2] * xx[3] / zFar;
>> > gl_Position = xx;
>> >
>> > Thanks for your precious help Marcus.
>> >
>> >
>> > 2007/5/9, Marcus Lindblom <[EMAIL PROTECTED]>:
>> >>
>> >> Stefano wrote:
>> >> >>
>> >> >> Test some values to see if you are getting discrete steps, or 
>> simply
>> >> set
>> >> >> nearest_mipmap_nearest and see if it yields equivalent results.
>> >> > Here you have the results.. the first image is with
>> >> > GL_NEAREST_MIPMAP_NEAREST.. the second one with
>> >> > GL_LINEAR_MIPMAP_LINEAR -->
>> >> > http://steffoz.altervista.org/depth.htm
>> >> > I think the filtering is visible. So, if also the filtering is 
>> good,
>> >> what
>> >> > else could be? :(
>> >> Yup, there is filtering all right. I can't see if mipmap-filtering is
>> >> done though, but that ought to be there since you at least get
>> bilinear.
>> >> (However, I'm still not 100% convinced. :)
>> >> >> What card are you using btw? (Don't know if you've said that 
>> before)
>> >> >> I _know_ some cards don't filter depth component textures at all.
>> >> >> (The GF7800 doesn't, for instance.)
>> >> > I own a nv6600.
>> >> Right. I don't know much about that card though.
>> >>
>> >> You might want to try the OpenGL.org forums. I'm have the feeling 
>> this
>> >> isn't OpenSG related anymore, so there might be ppl there who knows
>> more
>> >> about this. Let us know if you figure it out. (Sorry for not being 
>> able
>> >> to help more.)
>> >>
>> >> Cheers,
>> >> /Marcus
>> >>
>> >>
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