# [Chimera-users] Draw Line

Elaine Meng meng at cgl.ucsf.edu
Thu Aug 17 09:32:19 PDT 2017

```Hi Catherine,
This is another basic geometry question, similar to what you asked before (<http://plato.cgl.ucsf.edu/pipermail/chimera-users/2017-July/013706.html>), and not a Chimera issue.   Use geometry (check in a textbook or look online) to figure out the coordinates of the two ends of the line or cylinder you want to display.  In your question, you only gave a point and a direction, so there are a infinite number of points along that line and thus an infinite number of choices for the coordinates of the two ends of the cylinder.   You would still have to decide which segment of that infinite line you want to depict.  Basically the points on the line are your point coordinates plus or minus any multiple (including fractional) of the direction vector values.

Now, here is the Chimera question part:

Once you figure out the coordinates of the two ends you can put that in a BILD format file to show a cylinder just like we discussed before.
<http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/bild.html>

The BILD format also allows you to draw an arrow or line instead (see .arrow or .dot + .draw).

Or, make a PDB file with two fake atoms with those coordinates connected by a bond, which could be shown as wire or stick.

Good luck,
Elaine
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Elaine C. Meng, Ph.D.
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Aug 17, 2017, at 8:09 AM, Catherine Jenifer Rajam Rajendran <catrajen at umail.iu.edu> wrote:
>
> Hi Eric,
> Can you please tell me what are the ways to draw an axis. I have a directional vector - x, y, z coordinates (e.g., 0.407 -0.747 0.526) and a point (14.395, 37.07, -12.029). How to draw an axis in chimera tool with these two data?
> Thanks,
> Catherine

```