8

Point Cur ve on Surface 1177
on a surface can exist in three dimensions. The
more complex the 3D surface, the more effort it
can require to create and edit a curve on a surface.
Visual feedback can help you draw the curve. T he
point whose surface you first click is shown as a
blue square, and the surface’s minimum UV point
is shown a s a plus sign (+). As you draw the curve,
it is displayed interactively in viewports.
Dra wing in a Vi ewpor t
Whenyouclicktopositionapoint,theclickis
projected in the viewport’s Z dimension. That is,
your click is projected "through the screen" and
ontothesurface.Thisisastraightforwardwayto
create a curve on a surface if the portion of the
surfacewherethecurvewilllieisclearlyvisiblein
the viewport. However, this method do esn’t let
yo u place points on surface locations that are not
visible in the v iewport (they are on back faces, lie
behind other geometry, and so on).
Using the Edit Cur ve on Sur f ace Dia log
The Edit Curve on Surface dialog (page 1–1230)
letsyoueditcurvesonsurfacesasyoueditregular
curvesinaviewport.Themainpartofthedialog
is a two-dimensional view of the surface. The
controlsprovidetypicalcurveeditingfunctions.
Whileyouarecreatingapointcurveonsurface,
the2DViewtogglecontrolsdisplayoftheEdit
Curve on Surface dialog.
You can edit the points in point curves on surfaces
at the
Point sub-object level (page 1–1124) ,as
you edit other kinds of points. You can tr ansform
points in point curves on surfaces, but you c an’t
movethepointsoffthesurface.UsingthePoint
sub-object level is an alternative to editing these
points by using the Edit Curve on Surface dialog.
Procedure
To create a point curve on surface:
1.
In a NURBS object that contains at least
onesurface,turnonCreatePointCurveon
Surface in the NURBS toolbox, or Point on Surf
on the Create Curves rollout.
2. Do one of the following:
•Drawthecurveintheviewport,usingthe
mouseabovethesurface.
• Turnon2DView. ThisdisplaysanEdit
Curve on Surface dialog, which lets you
create the curve in a two-dimensional (UV)
representation of the surface.
3. Right-click to end curve creation.
Interf ace
Point curves on surfaces have point sub-objects
that you can transform and edit in v iewports as
you do with plain point curves.
(There is no special Move Surface Points button as
there was prior to 3ds Max 3.)
Point Curve on Surface rollout (creation time)
Trim Controls group
Trim—When on, trims the surface against the
curve. When off, the surface isn’t trimmed.
If it’s impossible to trim with this curve, the surface
is displayed in the error color (orange by default).
For example, the curve is unusable for trimming if
it doesn’t form a closed loop.