[x, y] = getpts(fig) lets
you choose a set of points in the current axes of figure fig using
the mouse. Coordinates of the selected points are returned in X and Y.
Use normal button clicks to add points. A shift-, right-, or
double-click adds a final point and ends the selection. Pressing Return or Enter ends
the selection without adding a final point. Pressing Backspace or Delete removes
the previously selected point.
[x, y] = getpts(ax) lets
you choose points in the axes specified by the handle ax.
[x, y] = getpts is the same
as [x,y] = getpts(gcf).