Re: [Visualpython-users] Contour lines using vPython

[Bruce S. <Bru...@nc...>]

The curve object will connect a list of points with line segments,
which sounds like what you want.

There is a trick to drawing field lines which you might wish to
implement, to avoid a systematic error. From a starting point where
you know the field direction, project a line in that direction and
evaluate the field at a new location on that line. Draw perpendiculars
to the two vectors and find where those perpendiculars meet (this is
assuming a 2D field). Imagine that point as the center of a circle,
and swing a circular arc around that center, starting from the first
point and ending on the line that is perpendicular to the second field
vector. Approximate the arc with a straight line. Evaluate the field
at the end of the arc, which will be nearly parallel to the second
field vector that you evaluated. Repeat.

At http://www.matterandinteractions.org/Content/Materials/programs2.html
you'll find a program fields.py which you might find interesting, as
it displays many properties of E and B fields, but not field lines
(nor equipotential lines/surfaces).

Bruce Sherwood

On Wed, Apr 20, 2011 at 6:47 AM,  <dal...@ea...> wrote:
> I'm looking for a way to draw E and B fields using vPython. I have the equations to find the vector at a point, but want to draw contour lines between two particles just as a start. Any suggestions or code segment that shows how to do that?
>
> Thanks,
> -d