Graphics Programs Reference
In-Depth Information
USING OBJECT SNAPS AND OSNAP TRACKING IN 3D SPACE
If you need to place objects in precise locations in 3D, such as at endpoints or midpoints of other
objects, you can do so using object snaps, just as you would in 2D. But you must take care when
using osnaps where the Dynamic UCS is concerned.
In the exercise in the section “Rotating Objects in 3D Using Dynamic UCS,” you were asked to make
sure you placed the cursor on the side of the box that coincided with the rotational plane
before
you
selected the Endpoint osnap. This ensures that the Dynamic UCS feature has selected the proper
rotational plane; otherwise, the box may rotate in the wrong direction.
In some operations, you can't use osnaps in perspective mode. Osnap Tracking also doesn't work in
perspective mode. Switch to a parallel projection view if you know you'll want to use osnaps. (See
the section “Changing from Perspective to Parallel Projection” later in this chapter.) If you need to
snap to points that are in the back of an object, switch to the 2D or 3D wireframe visual style. See
the section “Getting a Visual Effect” later in this chapter for more on visual styles.
Drawing on a 3D Object's Surface
In the rotation exercise, you saw that you can hover over a surface to indicate the plane of rota-
tion. You can use the same method to indicate the plane on which you want to place an object.
Try the following exercise to see how it's done:
1.
Click the Center, Radius tool near the middle of the Tool Sets palette or enter
C
↵.
2.
Place the cursor on the top surface of the rectangle, as indicated in the top image of
Figure 19.15, and hold it there for a moment. The surface is highlighted and the cursor
aligns with the angle of the top surface.
FIGURE 19.15
Drawing circles
on the surface
of a 3D solid
Hover over the
top surface and
select a point at
the center of
the box.
Offset the
circle toward
the center.
