VMD-L Mailing List

From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Thu May 31 2012 - 21:14:54 CDT

On Thu, May 31, 2012 at 5:03 PM, bsnmrem-obj_at_yahoo.com
<bsnmrem-obj_at_yahoo.com> wrote:
> Dear Alex:
>
> Here is the post I was referring to:
>
> http://www.ks.uiuc.edu/Research/vmd/mailing_list/vmd-l/1820.html

this is a very old post. i am not aware of what VMD
command john is referring to. i know that there is
an OpenGL primitive that can be used to turn a sphere
into an ellipsoid and john and i have been discussing
on occasion to have this implemented in VMD, but
right now. the only option would be to approximate
the ellipsoid through a set of triangles writing a custom
command as john mentions. you might be able to
make those smooth and look more like an ellipsoid
using the trinorm primitive instead.

axel.

> I would like to draw many ellipsoids and be able to visualize
> them. The result could be something just like this:
>
> mol new
> draw material Opaque
> draw color 1
> draw sphere {0.1 0.7 0.2} radius 0.3 resolution 100
> draw color 2
> draw sphere {1.0 2.0 1.0} radius 1.2 resolution 100
> mol new
> draw material Transparent
> draw color 3
> draw sphere {0.0 0.0 0.0} radius 1 resolution 100
>
> Except that the spheres should be ellipsoids.
>
> Each ellipsoid would be given by the length of its semi-principal
> axes. Also, the ellipsoid could be translated and rotated. The
> translation would be given by a three dimensional vector. The
> rotation could be given either by a rotation matrix in three
> dimensions or three angles, whichever is easier to work with.
>
> Thank you for your attention.
>
>
>
> ----- Original Message -----
> From: Axel Kohlmeyer <akohlmey_at_gmail.com>
> To: "bsnmrem-obj_at_yahoo.com" <bsnmrem-obj_at_yahoo.com>
> Cc: "vmd-l_at_ks.uiuc.edu" <vmd-l_at_ks.uiuc.edu>
> Sent: Thursday, May 31, 2012 12:35 PM
> Subject: Re: vmd-l: Drawing an ellipsoid
>
> On Thu, May 31, 2012 at 9:44 AM, bsnmrem-obj_at_yahoo.com
> <bsnmrem-obj_at_yahoo.com> wrote:
>> Hi!
>>
>> I would like to draw an ellipsoid. I have read other posts about it and
>> someone said that it could be done by scaling a sphere
>
> "someone" is a horribly bad source of information.
> almost as bad as the "friend of a friend".
>
>> non-uniformly. However, I could not find out how to scale a sphere
>> non-uniformly. Can someone please give me an example?
>
> there is too little information here to give a reasonable answer.
> what is it exactly that you want to do with that ellipsoid in VMD?
>
> axel.
>
>> Thanks,
>> Brian
>>
>
>
>
> --
> Dr. Axel Kohlmeyer
> akohlmey_at_gmail.com  http://goo.gl/1wk0
>
> College of Science and Technology
> Temple University, Philadelphia PA, USA.
> 

-- 
Dr. Axel Kohlmeyer
akohlmey_at_gmail.com  http://goo.gl/1wk0
College of Science and Technology
Temple University, Philadelphia PA, USA.