To select different types of component simultaneously, first select the components of one type, press Shift while changing the selection filter, and then add the other components to the selection.
In Softimage, curves are linear (degree 1) or cubic (degree 3) NURBS (Non-Uniform Rational B-Splines). NURBS are a class of curves that computers can easily manipulate, allowing for a great deal of flexibility in modeling.
You cannot render curves because they have length but no width. Instead, you use curves in other ways, for example:
• To build meshes or surfaces as described in Generating Objects from Curves [Modeling and Deformation Basics].
• To define extrusions as described in Duplicating and Extruding Components Along a Curve [Polygon Modeling].
• To define shapes that can be tessellated into polygon meshes as described in Converting Curves to Polygon Meshes [Polygon Modeling].
• To control deformations as described in Deforming by Curves and Spine Deformations [Modeling and Deformation Basics].
• As paths and trajectories for animation as described in Animating along Paths and Trajectories [Animation].
Curve Components and Attributes
Curves have many components and attributes. You can display these components and attributes in the 3D views and select them for various tasks.
Types of Curve Components and Attributes
Points, sometimes called control points or CVs (control vertices), define the curve mathematically.
• In linear curves, the points lie on the curve itself. You need at least two points to define a linear curve.
• In cubic curves, the curve is interpolated between the points. You need at least four points to define a cubic curve.
You can modify curves by moving, adding, and deleting points. For more information, see Adding and Deleting Components on Curves.
Knots are the points at which curve segments meet. For linear curves, knots and control points are equivalent. For cubic curves, it requires multiple control points to define the trace of a segment and the position a knot.
You can add or remove knots as described in Adding and Deleting Knots Manually, and you can manipulate them as described in Using the Tweak Curve Tool.
Segments are spans of a curve between consecutive knots. For display purposes, they are subdivided and approximated by several straight line segments. To specify how many straight line segments are used, see Geometry Approximation on NURBS.
NURBS hulls (called simply lines in previous versions of Softimage software) are display lines that join consecutive control points. It can be useful to display them when working with curves and surfaces.
Any point along a curve can be defined in terms of a single parameter U. You can display NURBS Boundaries to show the beginning (U = 0) of a curve. This display option is sometimes also called boundary flags or edge flags. This lets you see which end of a curve is the start, as well as to see where the join is in a closed curve.
Isopoints are arbitrary locations on a curve or surface. You can select them for use with certain modeling operations (such as Extract Segment). You can also modify the trace of a curve by manipulating isopoints as described in Using the Tweak Curve Tool.
Subcurves are individual NURBS curves that make up curve objects. Primitive curves like a circle are composed of a single subcurve, but text and imported EPS curves may be composed of many subcurves. You can extract subcurves as separate objects as described in Extracting Curves from Subcurves.
Viewing Curve Components and Attributes
You can display or hide curve components, like points and hulls, in the 3D views using exactly the same way as other components and attributes. A quick summary is provided here — for complete details about viewing, see Viewing 3D Objects [Interface and Tools].
To display or hide components in a single 3D view
Do one of the following:
• Click the eye icon (Show menu) and choose the corresponding component option. You can press Shift to keep this menu open while you toggle multiple items.
or
• Press Shift+s or click the eye icon and choose Visibility Options. The Camera Visibility property editor contains many more options than the menu, for both selected and unselected objects.
To display or hide components in all open 3D views
Do one of the following:
• Choose Display on the main menu and then choose the corresponding component option.
or
• Choose Display > Visibility Options (All Cameras). This opens the Camera Visibility property editor for all open geometry views.
You select curve components in exactly the same way as anything else in Softimage: using the selection filters, tools, and modes available on the Select panel. Selection is fully described in Selecting [Scene Elements] and is quickly summarized here.
To select components
1. Select the object that owns the components you want to select.
To select components on multiple objects, select all the associated objects first.
2. Set the selection filter to the desired component type. See Summary of selection filters.
3. If desired, change the selection tool. See Summary of selection tools.
4. Click and drag on the components in a 3D view.
The specific mouse buttons and modifier keys that you use to perform different actions — like selecting, adding to the selection, toggling, and deselecting — depend on the selection interaction model.
For more complete details, see Selecting Components Using the Different Interaction Models [Scene Elements].
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To select different types of component simultaneously, first select the components of one type, press Shift while changing the selection filter, and then add the other components to the selection. |
Component selection filters determine what type of component you can select on the active geometric objects. The most commonly used filters are available as buttons on the Select panel, while more filters are available from the Filter menu below the buttons.
The component selection filters are context-sensitive; they change depending on what type of object is active. The illustration above shows the component filters available when a curve object is selected.
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There are additional filters on the Filter menu that allow you to select, for example, border points or Bézier knots. These are examples of custom filters. For information about creating your own filters, see the SDK Guide. |
The selection tools determine the mouse interaction used select objects. You can activate a selection tool using the commands on the Select > Tools menu. Alternatively, you can press one of the following keys:
• F7 for the Rectangle selection tool.
• F8 for the Lasso selection tool.
• F9 for the Freeform selection tool.
• F10 for the Raycast selection tool.
• Shift+F10 for the Rectangle-Raycast tool.
• F11 for the Paint selection tool (for curves, this works with points only).
Summary of selection modes
Selection modes are a combination of a filter and tool mapped to a single key for convenience. The only component selection mode that is useful for curve components is t for the Rectangle Point.
Autodesk Softimage v.7.5