From: Angus Dorbie (dorbie++at++sgi.com)
Date: 04/11/2001 14:40:58
Performer abstracts the load source API entry point into a common
subload interface. Hmm... is this using glCopyTexSubImage2DEXT. Looks
like subload doesn't go through convolution, I can understand why
because the edges of the subload would be unfiltered against the rest of
the texture so it's extremely difficult to support subload convolution
correctly, you'd have to fetch the border from the resident image.
You could try glCopyTexImage2DEXT no "Sub" but ultimately you may have
to go back to the host. Just watch you only have convolution on one way
otherwise you might convolve on the read and on the load depending on
the exact API you use. That caught me out once. This is going to be
heavily GE limited so the trip to host may not be overly worrying given
the performance implications of the convolution.
Cheers,Angus.
Stephane Jaeger wrote:
>
> Hi,
> I am currently rendering a scene with one channel and using a texture of
> the previously rendered scene with another channel. To update my
> texture, I use the pfTexture->subload method to read the backbuffer
> after the first channel's rendering. In the meantime I'd like to blur my
> texture in a very fast way. Therefore I thought It would be fine to use
> the GL_CONVOLUTION_2D_EXT OpenGl extension as described in Angus
> Dorbie's web site. The trouble is that it seems this extension needs a
> glReadPixel to operate whereas I am using a pfTexture->subload. I d like
> to keep the subload since I think it's the fastest way to transfer the
> framebuffer to a texture, yet I don t know how to handle the
> GL_CONVOLUTION_2D_EXT. Does anybody have any idea about this ? How to
> improve/save performance ?
> Thanks,
> Stephane
>
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This archive was generated by hypermail 2b29 : Wed Apr 11 2001 - 14:41:33 PDT