these are some notes based on discussion 12/19/01:
=================================================

functions to be implemented in the API:

set_projection(F, mode)     where F is a matrix dxp (proj dim x num cols)
                            that defines the projection of variables.
                            mode is the tour type, that is display tour type,
                            that we want to set the projection in. it
                            can be TOUR1D, TOUR2D, TOURCORR currently.
                            there may be more tour types in the future.

get_projection(mode)

set_lims()                  these functions are for setting the min/max
get_lims()                  to use for scaling the raw data into the plot.
                            they are not truly a part of the tour API,
                            but may be needed to build exact copies of the
                            ggobi plot in an R window.

set_scale_shift()           these are routines to setting/getting the        
get_scale_shfit()           screen scaling and shifting. they are not part
                            of the tour API, but may be needed to build
                            exact copies of the ggobi plot in an R window.

pause_tour_proc()           to pause the tour

stop_tour_proc()            to remove the tour idle process

get_idleid()                to get the identity of the tour idle process
                            in case we want to take it over from R

set_target_projection()     similar to set_prejection, but used to fill in
                            the next target plane that the tour will
                            interpolate towards

set_active_vars(tourvars, mode)  sets the binary vector (length num cols) of 
get_active_vars(mode)       indicators for the tour. a 1 represents a 
                            variable that is actively being toured, and 
                            a 0 means the variables is not part
                            of the current tour.

set_speed(delta, mode)      this is a float constant that alters the
get_speed(mode)             step size in the tour.

set_history(tourhist, mode) gets/sets an array of basis planes
get_history(mode)

in the first release we will ideally have set_projection and
get_projection available through the API.
