VMD User's Guide

functions (e.g., listall()) overlap. All commands are listed below, with the name of the modulegiven by the section heading.9.5.1 animatePython operations available from the animate module, used to control which coordinate frames aredisplayed.• forward():• reverse(): forward() and reverse() causes VMD to start animating frames automaticallyin order of increasing or decreasing frame number, respectively.• once():• rock():• loop(): once(), rock(), andloop() control how frames are cycled when VMD is animatingaseriesofframes. once() causes VMD to stop when it reaches the first or last frame. rock()causes VMD to reverse direction each time it gets to the beginning or end. loop() causesVMD to continue from the beginning when reaches the last frame, or from the last frame ifit gets to the beginning.• style(): Returns either ’Once’, ’Rock’, or’Loop’, corresponding to the animation modeVMD is currently in.• goto(frame):Set the animation to the given frame, and pause the animation.• prev():• next():• pause():Step to the next-lowest frame, then pause.Step to the next-highest frame, then pause.Stop animating frames.• speed(value): Get/set the relative rate at which VMD animates frames. value should liebetween 0 and 1. If a value less than 0 is given, then the speed will not be changed. The newvalue of the speed is always returned.• skip(value): Get/set the number of frames to skip when animating. A value of 1 meansevery frame is shown; 2 means every other frame is shown; etc. If value is 0 or less, no changeis made. The new value of the speed is always returned.• is active(molid): Returns whether the molecule with the given id is active; that is;whether it responds to animation or not.• activate(molid, trueorfalse): Make the molecule with the given id active or not. Activemolecules update their coordinate frames during animation; inactive molecules do not.133