Re: 3D plotting library

[Jon Trowbridge <trow emccta com>]

On Mon, Jan 24, 2000 at 03:37:10PM +0000, Aaron Lehmann wrote:
> I already have it operating in a canvas. I am using GnomeCanvasWidget
> rather than making my own item, and I don't know if this would be
> sufficient.

It might be.  To really work properly, it should not be opaque, but
should have a transparent background.

> OpenGL sounds really hard, and I'm not sure how usable it would be to
> people without 3d accelerator cards... would the performance from software
> rendering be acceptable? I really don't know how the performance of
> going through Mesa would compare with rendering directly to a drawable 
> as my demo does. 

Well, OpenGL certainly adds another layer of complexity.  However, I
am aiming high with Guppi, and I want to eventually be able to support
things like complicated volumetric rendering, the kind of imaging that
is most commonly associated with medical applications (MRIs, etc.).
That level of 3d is way beyond what we'd want to reinvent from
scratch.  So if OpenGL is going to enter Guppi anyway, there is no
harm in it happening sooner rather than later.

Also, the momentum for OpenGL on free platforms seems to be growing by
the day.  Mesa is being integrated into XFree4.  Our friends at
Precision Insight are finally solving the driver problems.  And 3d
accelerator hardware is getting cheap fast.

While unaccelerated OpenGL might suck for Quake3, I think that it
would be fine for the kind of smaller problems we'd probably be
throwing at it.  My slow PII does pretty well with the simpler
unaccelerated Mesa demos.

Now there is no reason there couldn't be both OpenGL and non-OpenGL 3d
plot types.  The question is whether it is worth the trouble to keep
two versions of the same thing in sync.  Maybe it is.  I don't know.
And even if I thought it was the worst idea ever, I'd still cheerfully
roll it into the Guppi distro if someone else wrote it and it was
cool.:-)

-JT


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