Extruding, Duplicating, and Insetting Polygon Mesh Components
Duplicating, extruding, and insetting are operations that copy selected polygons, edges, or points. This lets you create local details, such as indentations or protuberances like limbs and tentacles.
Two versions of the Extrude operator are responsible for all the various extruding, duplicating, and insetting effects:
• One version of the operator copies components along an axis. For more information about applying this operator, see Insetting, Duplicating, and Extruding Components Along an Axis.
• The other version of the Extrude operator copies components along a curve. For more information about applying this operator, see Duplicating and Extruding Components Along a Curve.
Different commands, on the Modify > Poly. Mesh menu of the Model toolbar as well as the Edit menu of the Edit panel, apply different presets of these operators to achieve different effects. (Of course, you can always adjust the parameters to modify the effects further or even change them completely.)
• For a description of the parameters that are specific to copying components along an axis, see Parameters Specific to Copying Along an Axis.
• For a description of the parameters that are specific to copying components along a curve, see Parameters Specific to Copying Along a Curve.
• For a description of the parameters that are common to both versions of the operator, see Common Parameters.
What’s the Difference Between Extruding, Duplicating, and Insetting?
Extruding, duplicating, and insetting all involve copying components. They differ in how the components are copied, as well as how they are modified after copying.
Extruding copies the selected components and transforms the new geometry. The new components are connected to the original selection.
Like extruding, duplicating copies the selected components and optionally transforms the new geometry. However, the new components are not connected to the original selection. In addition, duplication applies only to polygons, and not to points or edges — you can apply the command to points and edges but the effect is the same as extruding.
Insetting copies the selected polygons and then shrinks the contours of the new geometry. The boundary edges of the resulting polygons always remain parallel to the originals. The effect is as if you extruded the polygons by a length of 0, and then offset the result by a negative value (see Offsetting Polygon Contours).
Like duplication, insetting applies only to polygons, and not to points or edges — you can apply the command to points and edges but the effect is the same as extruding (by a length of 0).
Insetting, Duplicating, and Extruding Components Along
an Axis
The Extrude (Along Axis) operator is used to extrude, duplicate, and inset polygon mesh components. There are several ways to apply this operator with different presets as default values.
Copying Components Quickly Using a Hotkey
You can quickly copy polygons, edges, and points on polygon mesh objects using Ctrl+d (no subdivisions) or Ctrl+Shift+d (multiple subdivisions). While these key combinations are used for duplication when objects are selected, they apply the Extrude (Along Axis) operator when polygon mesh components are selected. In the case of selected polygons, you can choose whether to extrude or duplicate by setting a preference in Duplicate Options.
To copy components with no subdivisions
1. Select the polygons, edges, points, or clusters to copy.
2. Press Ctrl+d. Alternatively, this command is also available from Edit > Duplicate/Instantiate > Duplicate Single.
The components are immediately extruded or duplicated, but the new components are initially superimposed on the originals. The new components are automatically selected so that you can scale, rotate, and translate them interactively using the transformation tools.
Although the Extrude Op property editor does not open automatically, you can still display it and change values through the polygon mesh’s operator stack as described in Operator Stack [Modeling and Deformation Basics].
To copy components with multiple subdivisions
1. Select the polygons, edges, points, or clusters to copy.
2. Press Ctrl+Shift+d. Alternatively, this command is also available by choosing Edit > Duplicate/Instantiate > Duplicate Multiple.
The components are immediately extruded or duplicated with 5 subdivisions along their local Y axis with a length of 1.
Although the Extrude Op property editor does not open automatically, you can still display it and change values through the polygon mesh’s operator stack as described in Operator Stack [Modeling and Deformation Basics].
To set the behavior when copying polygons
1. Open the Duplicate Options property editor by choosing Edit > Duplicate/Instantiate Options.
This property editor is also available under Commands in your preferences. For more information about preferences in general, see User Preferences [Data Management]
2. Set the desired value for Duplicated Items - Polygons. You can choose either Duplicate or Extrude.
1. Select the polygons, polygon clusters, or polygon mesh objects to duplicate.
2. Choose Modify > Poly. Mesh > Duplicate Polygons from the Model toolbar.
The polygons are immediately duplicated, but the new components are initially superimposed on the originals. The new polygons are automatically selected so that you can scale, rotate, and translate them interactively using the transformation tools.
Although the Extrude Op property editor does not open automatically, you can still display it and change values through the polygon mesh’s operator stack as described in Operator Stack [Modeling and Deformation Basics].
Extruding Components Along an Axis
1. Select the polygons, edges, points, clusters, or polygon mesh objects to extrude.
2. Choose Modify > Poly. Mesh > Extrude Along Axis from the Model toolbar.
The components are extruded with the default values and the Extrude Op property editor opens.
3. Set the values as desired:
- For a description of the options that are specific to Extrude Op (Along Axis), including Length, Frame, and Maintain Orthogonality, see Parameters Specific to Copying Along an Axis.
- For a description of the options that are common to both Extrude Op (Along Axis) and Extrude Op (Along Curve), including Duplicate, Inset, Merge, Skirting Ratio, Subdivs, and Transform, see Common Parameters.
1. Select the polygons or polygon clusters to inset.
2. Choose Modify > Poly. Mesh > Inset Polygons from the Model toolbar.
The polygons are inset with the default values and the Extrude Op property editor opens.
3. Set the values as desired:
- For a description of the options that are specific to Extrude Op (Along Axis), including Length, Frame, and Maintain Orthogonality, see Parameters Specific to Copying Along an Axis.
- For a description of the options that are common to both Extrude Op (Along Axis) and Extrude Op (Along Curve), including Duplicate, Inset, Merge, Skirting Ratio, Subdivs, and Transform, see Common Parameters.
Parameters Specific to Copying Along an Axis
There are several parameters that are specific to Extrude Op (Along Axis) and are not found in Extrude Op (Along Curve):
• Length is the length of the extrusion in Softimage units.
If you are defining shapes in local shape mode, it is better to adjust this parameter than to translate the components interactively. Otherwise, you might not get the expected results as the local reference frame changes.
• The X, Y, and Z options specify the axis of extrusion. You can activate multiple axes to extrude along the combined unit vector.
• Frame specifies the coordinate system for the axis of extrusion, as well as for the parameters on the Transform tab:
- Object uses the center of the parent polygon mesh object.
- Component uses the local system of the selected components.
• Maintain Orthogonality ensures that the Y axis of the local reference frame is orthogonal to the selected components even when the object has been scaled non-uniformly. Only the existing transformations when the extrusion is applied are considered; if the object is animated or transformed later, the new values are not considered. This option is available only when Frame is set to Component.
Duplicating and Extruding Components Along a Curve
The Extrude (Along Curve) operator is used to extrude and duplicate inset polygon mesh components using a curve as the path. There are a couple of ways to apply this operator with different presets as default values.
To duplicate or extrude polygon mesh components along a curve
1. Select the polygons, edges, points, clusters, or a polygon mesh objects to extrude.
2. Choose one of the following commands from the Model toolbar:
- Modify > Poly. Mesh > Duplicate Polygons Along Curve. This works with polygons, polygon clusters, and polygon mesh objects only. Points and edges are extruded instead of duplicated.
or
- Modify > Poly. Mesh > Extrude Along Curve. This works with any type of component.
3. Pick a curve object.
The components are duplicated or extruded with the default values and the Extrude Op property editor opens.
4. Set the values as desired:
- For a description of the options that are specific to Extrude Op (Along Axis), including Start, End, Autorotate, and Perpendicular, see Parameters Specific to Copying Along a Curve.
- For a description of the options that are common to both Extrude Op (Along Axis) and Extrude Op (Along Curve), including Duplicate, Inset, Merge, Skirting Ratio, Subdivs, and Transform, see Common Parameters.
Parameters Specific to Copying Along a Curve
There are several parameters that are specific to Extrude Op (Along Curve) and are not found in Extrude Op (Along Axis):
• Start and End control the offset of the extrusion from either end of the curve, as a percentage of curve length.
• Autorotate rotates the curve of extrusion so that the tangent at its start is aligned with the normal of each selected component.
• Perpendicular rotates the extruded components so that they are perpendicular to the curve of extrusion at each subdivision.
The Extrude Op (Along Axis) and Extrude Op (Along Curve) property editors have several parameters in common: Duplicate Polygons, Inset, Merge, Skirting Ratio, Subdivs, and the Transform settings.
Duplicate Polygons is a toggle that controls the behavior of the Extrude operator with polygons. Different commands apply presets with different default values for this option: when it is off, the new polygons are connected (extruded) and when it is on, the new polygons are disconnected (duplicated).
See What’s the Difference Between Extruding, Duplicating, and Insetting? for more details and illustrations.
The Inset options allow you to shrink the boundary of the new polygons. You can achieve similar effects by scaling using the options on the Transform tab, but with Inset the new edges are always parallel to the originals.
In addition, scaling does not always work well with concave polygons whose edges might self-intersect. Another difference is that the inset always applies to the entire extrusion, rather than being repeated per subdivision.
To control the inset amount
• Adjust Inset Amount in the Extrude Op property editor. Values are in Softimage units.
Negative values expand the boundary instead of shrinking it. If the extrusion length is 0, the resulting polygons will overlap. If you do not want overlapping polygons, you should offset the polygons (see Offsetting Polygon Contours) before insetting them.
When polygons have extreme concavities, setting high negative values will produce spikes.
To control the inset angle (along axis only)
1. Make sure that Length is not 0.
2. Activate Inset Locked.
Inset Amount becomes inactive and Angle becomes available.
3. Adjust Angle. Values are in degrees.
When you extrude adjacent components, the Merge option in the Extrude Op property editor controls whether they are extruded as one or separately.
When you are extruding or duplicating along an axis, there are only two options: on or off.
When you are extruding or duplicating along a curve, there are three options:
• None (per polygon) treats each polygon individually. It is the same as turning Merge off as shown above.
• Adjacent Polygons treats each group of connected polygons in the selection together, and treats disconnected groups separately.
• All treats all polygons together, whether or not they are connected. This is useful when you want to duplicate an entire object that is composed of disconnected islands of polygons. For example, you can duplicate text along a curve and keep the whole text aligned at each subdivision, rather than have each separate letter oriented differently.
When you extrude edges and points, the Skirting Ratio parameter in the Extrude Op property editor controls the relative size of the “base.”
When there are multiple subdivisions, the Skirting Ratio applies at each subdivision.
If the Skirting Ratio is 0.05 or less, then the components are extruded without a base. For example, this lets you extend boundary edges.
The Subdivs parameter in the Extrude Op property editor controls the number of subdivisions along the axis or curve of extrusion.
When you extrude along a curve, the Per Knot option controls whether the number of subdivisions is applied for every knot segment in the curve of extrusion or along the curve as a whole.
When this option is on, you can control the distribution of subdivisions in the extrusion by adding, removing, or moving points in the curve.
The options on the Transform tab of the Extrude Op property editor let you specify scaling, rotation, and translation values to be applied to the extrusion. The Transform Per Subdivision option applies the transformation values at each subdivision of the extrusion; if this option is off, the transformations apply to the extrusion as a whole.
Autodesk Softimage v.7.5