Hi Victor! A couple of comments, not really answering your question... perhaps others will have more direct suggestions about what is easy to program: (A) in version 1.6 the shape command includes "cone," so you can make 3D arrows from a cylinder and a cone: <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/shape.html> (B) more generally, with the 2dlabels command you can make 2D arrows and then change their locations without recreating them... however, that doesn't solve your problem because you need 3D arrows <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/2dlabels.html> Elaine ---------- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Feb 21, 2012, at 9:08 AM, Victor Muñoz wrote:

Dear all,

I'm trying to make a script that draws an arrow on every atom and every frame during a trajectory using the MD movie. Right now, the script creates a .bild file to draw the arrows, but it is not a very good approach since it is creating a new file for every frame of the trajectory. I was wondering if there's a way to do the same thing without having to create the .bild file.

I already checked the "shape" command but you can´t use it to draw an arrow. Maybe I should make a combination between a cylinder and a rectangle to draw an arrow? Is there any other easy way to do that?

Thanks in advance. Kind regards,