From: Alberto Sergio Garay (
Date: Fri Dec 19 2008 - 06:52:05 CST

Hi all

I'm trying to make my own animation script starting (learning) from
the vmd animation example. But when I run it in my PC it doesn't work.
It just only
did one iteration step and then exit. Am I doing something wrong?. I
just only copied the script from the webpage of vmd, saved it in a
file and run it.
Could anyone give any clue of how to solve it?

Below I've pasted the script I took from the vmd web page:

proc swing {} {
     # get rid of everything else (if there is anything)
     if [expr [molinfo top] != -1] { mol off all }
     # create a new graphics molecule to handle just this
     mol load graphics "swing"
     set mol [molinfo top]
     set center {0 0.5 0}
     set radius 0.125
     set offset ".25 0 0"
     set length 1
     set firsttime 1
     display resetview
     axes location off
     stage location off
     for {set i 0} {$i < 1000} {incr i} {
         display update off
         scale by 1.003
         rotate y by 5
         display update on
         set top1 [vecsub $center $offset]
         set top2 $center
         set top3 [vecadd $center $offset]
         # compute the bottom location
         set bot1 [vecsub $top1 "0 $length 0"]
         set bot2 [vecsub $top2 "0 $length 0"]
         set bot3 [vecsub $top3 "0 $length 0"]
         set xdiff [expr sin($i/10.0)]
         set ydiff [expr 1.0 - abs(cos($i/10.0))]

         if [expr $xdiff < 0] {
             set bot1 [vecadd $bot1 "$xdiff $ydiff 0"]
         } else {
             set bot3 [vecadd $bot3 "$xdiff $ydiff 0"]
         if $firsttime {
             set firsttime 0
             display resetview
           } else {
             graphics $mol delete all
         # draw the three different balls/strings in different colors
         graphics $mol color red
         graphics $mol sphere $bot1 radius $radius
         graphics $mol color green
         graphics $mol sphere $bot2 radius $radius
         graphics $mol color blue
         graphics $mol sphere $bot3 radius $radius
         graphics $mol materials off
         graphics $mol color red
         graphics $mol line $top1 $bot1
         graphics $mol color green
         graphics $mol line $top2 $bot2
         graphics $mol color blue
         graphics $mol line $top3 $bot3
         display reshape
     display update on

Thank you in advance


Dr. Sergio Garay
Facultad de Bioquimica y Cs. Biológicas
Universidad Nacional del Litoral
Santa Fe - Argentina
C.C. 242 - Ciudad Universitaria - C.P. S3000ZAA
Ph. +54 (342) 4575-213
Fax. +54 (342) 4575-221