8

1040 Chapter 9: Sur face Modeling
Remove—
Deletes selected edges and combines the
polygons that use them.
Removing one edge is like mak i n g it invisible. The mesh is
affected only when a ll or all but one of the edges depending
on one vertex are removed. At that point, the vertex itself is
deleted a nd the surface is retriangulated.
To delete the associated vertices as well,
press and hold CTRL while executing a
Remove operation, either by mouse or with the
BACKSPACE key. This option, ca l led Clean
Remove, ensures that the remaining p olygons are
planar.
Left: The original edge selec tion
Center: Standard Remove operation leaves extra vertices.
Right: Clean Remove with CTRL+Re move deletes the extra
vertices.
Edges with the same polygon on both sides usually
can’t be removed.
Wa rni ng: Use of Remove can result in mesh shape
changes and non-planar polygons.
Split—
Divides the mesh along the selec ted edges.
This does nothing when applied to a single edge in
themiddleofamesh. Theverticesattheendof
affected edges must be separable in order for this
option to work. For example, it would work on a
single edge that intersects an existing border, since
the border vertex can be split in two. Additionally,
twoadjacentedgescouldbesplitinthemiddleofa
grid or sphere, since the shared vertex can be split.
Ex trude—Lets you extrude edges manually via
direct manipulation in the viewport. Click this
button, and then drag vertically on any edge to
extrude it.
When extruding a vertex or edge interactively in the
viewport, you set the extrusion height by moving the
mouse verticall y and the b ase width by moving the mou se
horizontally.
Extruding an edge moves it along a normal and
creates new polygons that form the sides of the
extrusion, connecting the edge to t he object. The
extrusion has either three or four sides; three if the
edge was on a b order, or four if it was shared by
two polygons. As you increase the length of the
extrusion, the base increases in size, to the extent
of the vertices adjacent to the extruded edge’s
endpoints.
Following are important aspects of edge extrusion:
• When over a selected edge, the mouse cursor
changes to an Extrude cursor.