8

970 Chapter 9: Surface Modeling
Delete—
Removes edges from the framework. Use
this option with caution. Deleting an edge a lso
deletes any patches that share the edge.
Break—Splits an edge. Use this if you need to split
open an edge for general modeling operations.
Select one or more edges and then click Break.
After the break move the handles of adjacent
vertices to create a gap in the patch.
Note: To move the handles away from each other,
use SHIFT+Move.
Hide—Hides selected edges and the attached
patches.Youcannothideanentireobjectthisway;
at least one patch always remains visible.
Unhide A ll—Restores any hidden sub-objects to
visibility.
Weld group
Selected—Weld two edges that share vertices. Use
this to eliminate gaps on a surface.
Extrude and Bevel group
Extrude—Clickthisbutton,andthendraganyedge
to extrude it interactively. Hold down the SHIFT
key during this operation to create a ne w element.
• When the mouse cursor is over a selected edge,
it changes to an Extrude cursor.
• With multiple edges selected, d r ag ging on any
one extrudes all selected edges equally.
• Youcandragotheredgesinturntoextrude
themwhiletheExtrudebuttonisactive.
Click Extr ude again or r ight-click to end the
operation.
Extrusion—This spinner lets you extrude selected
edges outward or inward, depending on whether
the value is positive or negative. Hold dow n the
SHIFT key during this operation to create a new
element.
Normal—With Normal set to Group, extrusion
takesplacealongtheaveragednormalofeach
contiguousgroupofedges. Ifyouextrude
multiples of such groups, each group moves along
its own averaged normal. If Normal is set to Local
(thedefault),extrusiontakesplacealongeach
selected edge’s norm a l.
Sur f ace group
Vi ew Steps —Controls the grid resolut ion of the
patch model surface as depicted in the viewports.
Render S teps—Controls the g rid resolution of the
patch model surface when rendered.
Show Interior Edges—Enables the display of the
patch object’s interior edges in wireframe views.
When off, only the object’s outline is v isible. Turn
on to simplify the display for faster feedback.
UseTruePatchNormals—Determines how t he
software smoothes the edges between patches.
Default=off.
When the check b ox is off, the software computes
the surface normals from the smoothing groups
of the mesh object to which the patch object is
converted before rendering. These normals are not
accurate, especially with a low View/Render Steps
setting . When the check b ox is on, the software
computes true patch normals directly from the
patchsurfaces,whichcangeneratemoreaccurate
shading.
In the illustration below, a sphere was converted
to Editable Patch format, and then a vertex was
moved toward the center and rotated. The sphere
onthelefthasUseTruePatchNormalsturnedoff,
and the one on the right has it turn ed on. In both
cases, View Steps was set to 8.