Re: rendering speeds

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Chikai Ohazama (chikai@talula)
Mon, 23 Nov 1998 10:38:24 -0800 (PST)

You're correct. When zooming, the fill rate increases, so it takes longer
to render. You might try doing the following. Only render at the
original resolution (256^3, render in 256x256 window, if you want to
follow Nyquist then 512x512, but in most cases it shouldn't be necessary),
then read back the framebuffer, load into a 2D texture, clear the frame
buffer, then render a texture mapped quad at whatever zoom level you want.

This is will not work so well with volumes with geometry.

Hope this helps.
________________________________________________________________________
Chikai J. Ohazama, Ph.D. Silicon Graphics Computer Systems
Member of Technical Staff 2011 N. Shoreline Blvd. ms 525
Advanced Graphics Division Mountain View, CA 94043.1389
                                     Telephone: (650) 933-6533
                                     FAX: (650) 964-8671

On Mon, 23 Nov 1998, Robert van Liere wrote:

>
> For what its worth: we've got Volumizer running in a VR
> setting (i.e. head tracked, stereo, spatial input, large
> back projected display). We are looking at cell data
> comming from confocal microscopes.
>
> To be a succesfull VR environment, want to run at least
> 10 frames / sec minimum (in stereo). Frame rates are quite acceptable
> for sets with res 128x128x32. Frame rates are to low for sets of
> resolution of 256x256x64.
>
> Question: whenever we zoom into the volume, the frame rate slows
> down substantially. Why is this? (Perhaps because the triangles get
> very large (i.e. rasterizition bottlenecks) ?) Can we do something to
> improve the rendering speeds for these cases ?
>
> Any info will help,
> -- Robert van Liere
>
> ; uname -a
> IRIX64 perseus 6.5 05190003 IP27
> ; /usr/gfx/gfxinfo
> Graphics board 0 is "KONAL" graphics.
> Managed (":0.0") 2560x1024
> Display has 2 channels
> 4 GEs (of 4), occmask = 0x0f
> 4MB external BEF ram, 32bit path
> 1 RM7 board (of 1) 1/0/0/0
> Texture Memory: 64MB/-/-/-
> Small pixel depth
> 32K cmap
> Channel 0:
> Origin = (0,0)
> Video Output: 1280 pixels, 1024 lines, 72.00Hz (1280x1024_72.vfo)
> Channel 1:
> Origin = (1280,0)
> Video Output: 1280 pixels, 1024 lines, 72.00Hz (1280x1024_72.vfo)
>

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