spring for horizontal ticker (no acceleration)

Hi, I am trying to find the correct spring values for a horizontal ticker.. The behavior I want is:

1) No acceleration or deceleration, just constant smooth movement (I think damping: 0 is helping but, it still seems slow at the beginning and then speeds up)

2) No reverse / loop back. I am animating marginLeft from '2000px' to '-2000px' to get the scrolling from right to left but I don't want it to then loop back left to right.

Is this behavior possible with react-motion / spring?

No files, tests, or entry points are named. Start by reproducing the marginLeft spring from 2000px to -2000px and reviewing the react-motion API relevant to spring timing and interpolation. Done means establishing whether constant-speed, non-looping motion is supported or clarifying the required change.

Written by the indexing model from the issue text.