Graphics Programs Reference
In-Depth Information
Spherical coordinates: Expressed as @d<a1<a2 . Spherical coordinates are also
based on relative polar coordinates, but instead of a Z-coordinate to specify a loc-
ation above or below the X,Y plane, you specify an angle from the X,Y plane.
Using point filters
Coordinate entry as described in the previous section is fine if you already know the co-
ordinate values or distances in 3D space where you want to locate your points. Often,
however, you may need to derive 3D points from existing geometry without knowing
those exact values. Using point filters, you can locate new points based on existing
points. You can use point filters to construct 2D and 3D coordinates.
When AutoCAD prompts you to specify a point, you can either enter point filter values
at the command line, or bring up the right-click menu and choose a filter option from the
Point Filters submenu. After selecting a point filter option, specify a point to filter out
part of the coordinate value and then enter the requested value. For example, use the
.XY filter to enter your own Z-coordinate value after specifying a point on the current
working plane.
Object snaps and object snap tracking
Object snaps allow you to accurately specify points on existing objects
in a 3D model. You can use object snaps such as endpoints, midpoints, and center on 3D
objects, but AutoCAD also provides a set of object snaps specific to 3D modeling.
3D object snaps allow you to specify points on 3D objects that regular object snaps
won't recognize — for example, the center of a face, or a vertex. You enable 3D object
snaps by clicking the 3D Object Snap button on the status bar. Right-click the 3D Object
Snap button and choose the running 3D object-snap modes you want to use.
Object snap tracking allows you to calculate points that are not on an object by
using object snap points on existing objects. When working in 3D, you can not only track
points on the current X,Y plane but also along the Z-axis. While tracking points along the
Z-axis, AutoCAD provides feedback in the form of a tooltip that lets you know you are
moving along the Z-axis in the positive or negative direction.
Search WWH ::




Custom Search