8

1144 Chapter 9: Sur face Modeling
One or two blue curves appear on the surface to
indicate where the break will occur.
2. Whenyouhavedraggedtothelocationyou
want to break, click the surface.
Note: If you break a dependent surface, the new
"broken" surfaces are made independent.
You cannot break a trimmed surface.
To extend a sur face:
1.
Tur n on Ex tend .
2. Move the mouse over the surface without
depressing the mouse button. The edge that
will be extended is highlighted in blue.
3. When the edge you want to extend is
highlighted, press the mouse button, and then
drag vertically to increase the length of the
surface.
The surface extension is invalid and disappears if it
would cause the surface to intersect itself or if the
edge of the surface touches itself but is not closed.
For example, you can’t extend the top of a cylinder.
To join two surfaces:
1.
In a NURBS object that contains two surface
sub-objects, turn on Join.
2. If the gap between t he surfaces is small (less
than about 30 units), set the Tolerance value
greater than the distance of the gap.
3. Click one surface near the edge that you want
to connect. The edge that will be connected is
highlighted in blue. Drag to choose the edge
you want to connect. Without releasing the
mousebutton,dragtotheothersurface.The
edge of the other surface is als o highlighted in
blue. Drag on the other surface to choose the
edge to connect, and then release the mouse
button.
The surface that owns the highlighted edge is
highlighted in yellow, to help you distinguish
whichedgeyouarechoosingwhentwosurfaces
have coincident ed ges.
The
Join Surfaces dialog (page 1–1234)
is
displayed, wh ich gives you a choice of metho ds
forhowtojointhesurfaces.Whichevermethod
youchoose,thesoftwarecreatesasinglesurface
that replaces the two or iginal surfaces.
To close a surface:
Select the surface sub-object and then click
Close Rows or Close Cols.