Re: DVR, help!

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Rémi Arnaud (remi++at++remi.asd.sgi.com)
Tue, 8 Apr 1997 19:27:26 -0700 (PDT)


Jan Barglowski wrote:
>
> Hello Performers!
>
> I'm trying to simulate a view that is degraded on the outside but
> sharper on the inside. For example:
> ------------------------------
> | |
> | low-res |
> | |
> | ---------- |
> | | high | |
> | | -res | |
> | | | |
> | ---------- |
> | |
> | |
> ------------------------------
>
> I'm trying to do this with DVR on the low-res channel, and then overlaying
> another channel in the middle. The code I'm using is below:
>

 Dynamic Video Resolution is a mechanism that let you change the size
 of the computed images, without changing the resolution of the video
 output using a bilinear on-the-fly interpolation.
 It therefore affect the whole video.

 To do what you want, you need 2 separate projectors, using 2 different
 video output on the IR at different resolutions. This is often refered
 as Area of Interest in the Vis Sim vocabulary.

 If you want to do that on the same video, with one projector, you
 could use the texture readback extension.

 You render that low-res channel at for example 256x256 resolution.
 then you copy this image in a texture, and display that texture a
 on a flat polygon that is screen size.

 Then you render the center channel at higher resolution. You can use
 the low-res texture/polygon to do the clear of the channel.

 The copy of the image to the frame buffer is far to be free, so you
 may end up by spending more time than having everything at the
 same reolution, depending of the relative sizes of the high res
 and the low res views.

 Best Regards

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