VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Mon May 13 2002 - 13:25:59 CDT

Larry,
  Yes, I understand the desire for alpha transparency.
I think you'll be shocked to see the numbers on the percentage
of the user community using various types of hardware however:

Somewhere around 40% of the users
still lack decent hardware acceleration at the moment, with another
20% or so that have hardware acceleration, but don't have much more
than basic OpenGL features. Though many laptops have an OpenGL
driver that provides some level of acceleration, you'd be amazed at
how bad some of them are. I can tell you just based on the email
we get that there's still a large fraction of the VMD user community
that's eeking along on borderline-useful accelerator hardware.

Right now it looks like we've got around 1,242 users of the Mesa
versions of VMD 1.7.1, which are incapable of providing hardware acceleration.
Now, some of those people may have since gotten themselves OpenGL
accelerators, but nonetheless, that's still a good chunk of the overall
user community of that version. (Total of 3183 users of VMD 1.7.1 so far)
Going back to VMD 1.7, the picture looks similar, with about
1146 Mesa users out of a total of 3941 users. The difference in
download numbers is because VMD 1.7 has been released for a much
longer period of time, and also because in the VMD 1.7.1 distribution,
the largest group of Mesa users are the MacOS X user community, with
358 people using the MacOS X version of VMD 1.7.1.

So, one of our high priorities at present, is actually to get the
MacOS X version of VMD using the native OpenGL acceleration, as you
can see there are about 358 people that stand to benefit from that.
(and more that aren't using VMD yet because they don't want to have
 to use the X-windows based version we ship now, they are waiting
 for the native version...)
Once that's done, then I'd feel much better about spending the time
for alpha blending transparency and other things which demand more
hardware. In any case, I'll mark it up on our list and I'll see
what we can do.

  John

On Mon, May 13, 2002 at 02:09:19PM -0400, Laurence F. Wood wrote:
> Hey John,
>
> Second that! We use the alpha channel for transparency and it looks
> much better and provides more flexibility (allowing the user to select
> how transparent something is wins big time). I would wager that most
> users have opengl acceleration of some sort (most laptops come with
> opengl hardware these days.)
>
> Larry
>
> -----Original Message-----
> From: owner-vmd-l_at_ks.uiuc.edu [mailto:owner-vmd-l_at_ks.uiuc.edu] On Behalf
> Of Todd J. Furlong
> Sent: Monday, May 13, 2002 12:21 PM
> To: John Stone
> Cc: tripp_at_fis.unam.mx; vmd-l_at_ks.uiuc.edu; vmd_at_ks.uiuc.edu
> Subject: Re: transparency
>
> I see in the code that transparency is implemented using the "screen
> door" method with glPolygonStipple rather than using the alpha channel.
> I assume this was done because it is faster, but is there another
> reason? Maybe having the option for either method would be a desirable
> feature of VMD 1.8?
>
> -Todd
>
> John Stone wrote:
> > Hi,
> > To use the draw or graphics commands with your own materials,
> > you first need to define your material with the material editor
> > if you're not using one of the two default materials "Opaque" and
> > "Transparent". Once the materials are defined, you can use a command
> > like this to draw things with that material property (case sensitive):
> > draw material Transparent
> >
> > Or for your own material name:
> > draw material MyNeatoMaterial
> >
> > If you need to have graphics objects with different materials, then
> you'll
> > need to use the "graphics" commands with ID tags to differentiate
> which
> > one you're working on, etc. This is documented in the User's guide
> > here:
> > http://www.ks.uiuc.edu/Research/vmd/vmd-1.7.1/ug/node167.html
> >
> > The graphics/drawing interface is changing slightly for VMD 1.8, but
> > if you do your work on VMD 1.7.1 it should be easy to update later.
> >
> > Enjoy,
> > John Stone
> > vmd_at_ks.uiuc.edu
> >
> > On Fri, May 10, 2002 at 11:46:01AM -0500, tripp_at_fis.unam.mx wrote:
> >
> >>Hi L,
> >>
> >>this is a simple question, but nothing seems to work;
> >>how can I draw a transparent cylinder?
> >>
> >>I'm using VMD 1.7.1 in redhat
> >>
> >>thx
> >
> >
>
>
> --
> Todd J. Furlong
> Visualization Engineer
> Delta Search Labs
> 400 Technology Square
> Cambridge, MA 02139
> 617.551.4607
> 617.551.4651
> 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
Email: johns_at_ks.uiuc.edu                 Phone: 217-244-3349              
  WWW: http://www.ks.uiuc.edu/~johns/      Fax: 217-244-6078