Copyright Goodheart-Willcox Co., Inc. Chapter 11 Subobject Editing 273 A polysolid does not have parameter grips. Instead, a base grip appears at each corner and edge midpoint of the starting face of the solid. See Figure 11-4. Use these grips to change the cross-sectional shape or height of the polysolid. The corners do not need to remain square. Base grips also appear at the endpoint and midpoint of each segment center- line. Use these grips to change the location of each segment’s midpoint or endpoints. Grips in AutoCAD are multifunctional. For example, if dynamic input is turned on, you can hover over the parameter grips of an object to display various design param- eters. In Figure 11-5A, the box primitive is selected to display grips. Hovering over the parameter grip at the side of the base displays the length dimension. Hovering over parameter grips on other types of primitives, such as a cylinder or sphere, displays the corresponding dimension of the shape. See Figure 11-5B and Figure 11-5C. You can quickly subobject edit a primitive by selecting a parameter grip and typing a delta value to add or remove geometry. For example, suppose a cylinder has a height of 10 units. The new height requirement is 15. With dynamic input turned on, select the cylinder, pick the parameter grip at the apex, and drag it so the dynamic input changes to delta entry. In the dynamic input box, type 5 for the new height and press [Enter]. Swept Solids Extrusions, revolutions, sweeps, and lofts are considered swept solids and typi- cally have base grips located at the vertices of their profi les. These can be used to change the size of the profi le and, thus, the solid. Other grips that appear include: • A parameter grip appears on the upper face of an extrusion for changing the height. • A base grip appears on the axis of a revolved solid for changing the location of the axis in relation to the profi le. • Base grips appear on the vertices of a sweep path for modifying the swept object. Composite Solids Composite solids are created by using one of the Boolean commands (UNION, SUBTRACT, or INTERSECT) on a solid. Solids that have been modifi ed using any of the options of the SOLIDEDIT command also become composite solids, as do meshes converted into solids. The solid may still look like a primitive, sweep, loft, etc., but it is a composite. The grips available with the previous objects are no longer available, unless performing subobject editing on a composite created with a Boolean command (as discussed later in this chapter). Composite solids have a base grip located at the centroid of the base surface. This grip can be used to stretch, move, rotate, scale, or mirror the solid when the 2D Wireframe visual style is current. See Figure 11-6A. This grip also appears if no gizmo is selected to display when a 3D visual style is current. The gizmo drop-down list selection in the Selection panel on the Home tab of the Figure 11-4. A polysolid has a base grip at each corner and edge midpoint of the starting face of the solid and one at the endpoint and midpoint of each segment.