user selection of displayed points-- ideas solicited

[Joe Vaughan]

Hello,
  I am developing an application toallow a user to select points forming
the vertices of a polygon bounding points of further interest.  The
background is displayed using d.rast, and points and labels are
generated with d.sites and d.paint.labels.  I then use d.where to
capture the points the user wants as vertices.  I massage these points
into an ascii vector file and use v.in.ascii and v.support to get a
GRASS vector map, and then v.area allows me to redisplay it and fill it.
Now I want to make the vector file into a raster file, include any
necessary support files, and turn the area of my polygon ( or perhaps a
slightly larger area as might result from 'grow'ing it ) into a mask.
Then I want to use the mask to copy out just the sites of interest
somewhere else.   Questions:
*  r.support seems to only run in interactive mode.  How can I get
around this?
*  what determines the values in the resulting raster file?  Do I need
to have attribute values for my vector file to get  raster values?
*  Once I have my mask, what operation would do a good job of giving me
just the sites within my polygon?

Comments are appreciated.

               Joseph K. Vaughan
               University of Arizona
               Institute of Atmospheric Physics
               PAS Bldg, Rm 470
               Tucson, AZ    85721

I can also be reached by return mail on the internet or as
jkv at air.atmo.arizona.edu and by phone at 602/621-9663.