When you select the rotate tool and the viewport in which to work, Abaqus/CAE enters rotate mode. In this mode the cursor changes to two curved arrows, and a large circle appears in the viewport. To define the center of rotation, you can enter its coordinates directly or select a point from the viewport. Otherwise, Abaqus/CAE will rotate the view about the center of the viewport. If you select a center of rotation by selecting a position from the viewport or entering coordinates, that rotation center position overrides the view center and remains selected until you select a new rotation center, display a different object, or choose the default rotation center. Your view of the model rotates as you drag the cursor, and a rubberband line indicates the amount and the direction of rotation. As you rotate your view of the model, the view triad indicates the orientation of the global coordinate system.

The circle that is drawn when you enter rotate mode represents the silhouette of an imaginary sphere that surrounds the object. When you drag the mouse inside the circle, you might imagine that you are actually rotating the sphere, as you would a trackball. Your model is attached to the center of the sphere, so that rotating the sphere causes your view of the model to rotate as well.

You determine the axis of rotation as you move the cursor over the surface of the imaginary sphere. The rubberband line represents the intersection of a cutting plane with the sphere's surface, and the rotation axis is normal to this cutting plane. The angle of rotation is equal to the angle made by the rubberband line on the sphere's surface, so that dragging all the way across the circle produces a 180° rotation. Figure 5–5 illustrates the imaginary sphere and a rubberband line being dragged across its surface.

When you drag outside the circle, the rubberband line is superimposed on the edge of the circle, and your view of the object simply rotates about an axis normal to the screen and passing through the center of the circle. In the same way as it does for dragging inside the circle, the rubberband line represents the angle through which the object has rotated.

Using the default mode of view rotation is comparable to rotating the camera around the view center or selected center of rotation, as shown in Figure 5–6.

The alternate mode of the rotate tool, accessed by holding [Shift] while performing the manipulation, rotates the camera about itself, as shown in Figure 5–7. This moves the camera target and frustum without regard to the position of objects in the original view. Rotating the camera about itself is most useful when you are in movie mode and the camera is positioned inside the model. In this position, moving the camera target and frustum brings different portions of the interior of the model into view.

In either mode, it is usually easier to obtain a desired rotation by performing a sequence of smaller rotations rather than one large one. If you need to abandon the rotation and return to a known orientation, use either the predefined views in the Views toolbar or the cycle view tool . Using any of the predefined views will also reset the camera target to the center of the model.

Because X–Y plots are two-dimensional, Abaqus/CAE disables the rotate tool when an X–Y plot is displayed in the current viewport.

For information on related topics, click any of the following items:

• “An overview of the view manipulation tools,” Section 5.2.1

• “Rotating the view,” Section 5.6.3

• “Understanding camera modes and view options,” Section 5.1