VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Tue Aug 17 1999 - 00:55:58 CDT

Dear VMD-L,
  The fifth public alpha release of VMD 1.4 is available at the
VMD web site under the VMD 1.4 specific web pages:
    http://www.ks.uiuc.edu/Research/vmd/vmd-1.4/

This alpha version primarily includes improvements to the OpenGL
rendering code. There is a new "culling" button on the display form,
which enables/disables backface culling in the OpenGL version of VMD.
Backface culling can provide a substantial performance improvement
(up to twice the speed) on machines that have entry-level 3D graphics
hardware. (i.e. no geometry acceleration) The new culling feature is
intended to allow some VMD representations to render faster on low end
machines that lack significant acceleration. In the current implementation
there is a trade-off in displayed image quality for some representations
(representations which are not "closed" will have visible holes in this
 version of VMD. Future versions of VMD will close these representations
 so that the "holes" do not happen in any normal circumstance..)
The culling feature is only available in the OpenGL versions of VMD
presently.

This version of VMD also includes support for the SGI multisample
antialiasing extension to OpenGL, found on their high end graphics
systems such as RealityEngine, InfiniteReality, etc. The advantage
of the multisample based antialiasing is that it does not slow down
rendering like most antialiasing schemes do. Machines which lack
multisample buffering will have the antialiasing button disabled at
this time. We will complete an accumulation buffer based antialiasing
scheme for lower end machines in a future version of VMD.
The availability of an appropriate multisample buffer is determined
at start time, and appropriate messages are displayed at startup on
platforms (currently only SGI) which support the multisampling extensions
to OpenGL.

The depth cueing code in VMD has been modified to work around bugs
in the rendering hardware on a number of graphics products from
various vendors which had bugs in the display of linear fog.
(which is what VMD previously used to implement depth cueing)
The new code implements depth cueing using exponential^2 fog,
with a smaller fog density coefficient. Best results are obtained
when using a display which supports gamma correction, with a gamma
value of 1.0. We may provide a new feature to allow the user to
customize fog density in a future revision of VMD.

This version of the VMD includes the first steps in supporting
MacOS-X builds of VMD, as well as fixes for building VMD on AIX 4.2
using the IBM xlC compiler. This version also includes numerous
enhancements which were released in the alpha 4 version, although
we only released a windows distribution of alpha 4 at the time.

The next VMD 1.4 alpha release should be about 2-3 weeks from now,
depending on how things go with some experimental code we are working
on now, and should be the last 'alpha' release.

Thanks for using VMD!
  The VMD developers
  vmd_at_ks.uiuc.edu 

-- 
Theoretical Biophysics Group   Email: johns_at_ks.uiuc.edu
Beckman Institute              http://www.ks.uiuc.edu/~johns/
University of Illinois         Phone:  (217) 244-3349
405 N. Mathews  Ave              FAX:  (217) 244-6078 
Urbana, IL 61801, USA          Unix Is Good For You!!!