Modeling mesh objects
differs from modeling 3D solids and surfaces in some important ways.
Mesh objects do not have the mass and
volume properties of 3D solids. However, they do offer unique capabilities
that enable you to design less angular, more rounded models. Mesh
objects are easier to mold and reshape than their solid and surface
counterparts.
NoteThe capabilities
described in this section apply only to mesh objects created in AutoCAD 2010
and later. They cannot be used with legacy polyface or polygon mesh.
About Mesh Faces
Mesh objects are composed of faces and
facets.
Faces are non-overlapping
units that—along with their edges and vertices—form
the basic editable units of a mesh object. When you move, rotate,
and scale individual mesh faces, surrounding faces are stretched
and deformed in order to avoid introducing gaps. When gaps occur,
you can often close them by smoothing the object or refining individual
faces.
About Mesh Facets
Mesh faces have underlying structures,
known as facets. The density of the facet grid corresponds to the
smoothness of the mesh. As the smoothness level is increased, the
density of the underlying facet grid also increases. When you want
to confine detailed mesh editing to a smaller area, you can convert
facets to editable faces by using refinement.
Unlike faces, facets
cannot be individually modified. However, you can make them more
visible by modifying the VSLIGHTINGQUALITY system variable.
About Mesh Modeling
You can work with mesh objects
in the following ways:
- Add smoothness. Increase
or decrease smoothness levels to round the overall shape of the
model. The underlying density of the mesh facet grid increases as
the mesh object smoothness level increases (MESHSMOOTHMORE, MESHSMOOTHLESS).
- Refine the object to reset
the baseline smoothness level. Refine a mesh object to
convert the underlying facet grid to editable faces. Refinement also
resets the lowest level of smoothness that can be applied to the
object (MESHREFINE).
- Refine a face. Restrict
the refinement to a specific mesh face. This method avoids resetting
the smoothness baseline.
- Crease an edge. Remove
the smoothness from specified edges. You can also remove an existing
crease (MESHCREASE).
- Split or merge faces. Divide an existing face into separate components along
a specified path. Merge two or more faces to create a single face (MESHSPLIT, MESHMERGE).
- Collapse vertices. Alter
the mesh model by collapsing the vertices of adjacent faces to a
single point (MESHCOLLAPSE.
- Spin edges. Spin
the shared edge of adjacent triangular faces to alter the shapes
and orientation of the faces (MESHSPIN).
- Extrude a face. Extend a specified face by extruding it into
3D space. Unlike 3D solid extrusion, a mesh extrusion does not create
a separate object (MESHEXTRUDE).
- Repair holes. Close
a gap between faces by selecting the surrounding edges. Holes in
mesh objects can prevent you from converting a mesh object to a
solid object (MESHCAP).
Use Grip Editing with Mesh
Grips, as described in Use Grips to Edit 3D Solids and Surfaces,
are not available with meshes. However, you can manipulate the entire
mesh model or individual subobjects using the following methods:
- Subobject selection and
editing. Select faces, edges, and vertices the same way
you select 3D solid subobjects. Press Ctrl and click the component. The
subobject highlighting indicates what is selected. Press Shift and
click again to remove the selection from a subobject. By turning
on the Subobject Selection Filter, you can restrict selection to
a specific subobject, which you can select without pressing Ctrl.
See Use 3D Subobject Grips.
- Gizmo editing. When you select a mesh object or subobject, the
3D Move, Rotate, or Scale gizmo is displayed automatically. (You
can set which gizmo is displayed by default.) Use these gizmos to
modify the selection uniformly, or along a specified plane or axis.
See Use Gizmos to Modify Objects.
Because dense meshes
can be difficult to work with, you can change settings to improve
the display and behavior of grips.
- Set the subobject selection
filter to select only faces, edges, or vertices: Set
the DEFAULTGIZMO system variable
or use the shortcut menu.
- Set whether a grip on a
face, edge, or vertex is active immediately when you select the
subobject: Set the GRIPSUBOBJMODE system variable.
CommandsMESHCAP
Creates a mesh face
that connects open edges.
MESHCOLLAPSE
Merges the vertices
of selected mesh faces or edges.
MESHCREASE
Sharpens the edges of
selected mesh subobjects.
MESHEXTRUDE
Extends a mesh face
into 3D space.
MESHMERGE
Merges adjacent faces
into a single face.
MESHREFINE
Multiplies the number
of faces in selected mesh objects or faces.
MESHSMOOTHLESS
Decreases the level
of smoothness for mesh objects by one level.
MESHSMOOTHMORE
Increases the level
of smoothness for mesh objects by one level.
MESHSPIN
Spins the adjoining
edge of two triangular mesh faces.
MESHSPLIT
Splits a mesh face into
two faces.
MESHUNCREASE
Removes the crease from
selected mesh faces, edges, or vertices.
System VariablesDEFAULTGIZMO
Sets the 3D Move, 3D
Rotate, or 3D Scale gizmo as the default during subobject selection.
GRIPSUBOBJMODE
Controls whether grips
are automatically made hot when subobjects are selected.
VSLIGHTINGQUALITY
Sets the lighting quality
in the current viewport.