Bernard Leclerc (bleclerc++at++cae.ca)
Tue, 1 Oct 1996 09:33:25 -0400
> Some information:
>
> RE2, IRIX 5.3 --
>
> You can read the zbuffer successfully from Performer 2.0 in a draw
> callback routine using glReadPixels. You can have texturing enabled and
> multisampling visual enabled. I have now succeeded thanks to Jenny at
> SGI. Things work like they are supposed to, I just swapped GL_FLOAT and
> GL_DEPTH_COMPONENT in the glReadPixels and I never caught it until I
sent
> her my code.
>
Angus Dorbie replied:
> This seems misleading, are you saying you managed to read the zbuffer
> on RE2 while multisampling?
>
> Did you turn on pfAntialias or just have the visual without actually
> using multisampling?
>
> Did you mean Infinite Reality?
>
We're using the RE2, IrisGL, IRIX 5.3 and Performer 2.0
In order to read the depth component of a channel, we configured the frame
buffer with
RGBsize(12);
zbsize(32);
stensize(1);
mssize(4, 32, 1);
gconfig();
This way, we have anti-aliasing available and the normal Z buffer is also
active so we can read it to obtain the depth component with
readsource(SRC_ZBUFFER);
lrectread(x1, y1, x2, y2, parray);
Of course, the Z components obtained correspond to the closest pixels
written to the multisample buffer. It's not an average value - but it's
better than nothing.
As far as I know, there is no way to obtain the resulting depth component
from the multi-sampled buffer. Only the normal Z buffer can be read.
--
Bernard Leclerc CAE Electronics Ltd., 8585 Cote De Liesse
Technical Leader Saint-Laurent, Quebec, Canada, H4L-4X4
3-D Graphics Applications tel: +1 514 341 2000 extension 2275
bleclerc++at++cae.ca fax: +1 514 340 5496
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