Related topics…Press the TAB key to lock the cursor's direction of travel.
Example
Start the Line command and place the first line point.
Use an object snap to locate a specific location on another object.
Press the TAB key.
The marker is now constrained along the line between the first point and the point where the marker, was when you pressed the TAB key.
If grid snap is on and ortho is activated, the TAB direction lock snaps to grid lines.
If grid snap is on and ortho is not activated, the TAB direction lock snaps to the snap points.
Notes
Use direction lock constraint when you want the line to pass through the end of a curve and then go beyond it. Turn on end object snap. When you move the cursor close to the end of the curve, the marker snaps to the curve end. Press the TAB key and then move the mouse beyond the curve end and pick. The line will pass through the end of the curve.
Use direction lock constraint combined with the distance constraint to draw a curve of a specified length and then constrain the angle with the TAB key.
Specify a point that is a given distance above or below a point on the construction plane.
Draw a curve using elevator mode
Start the Curve command and place the first point.
At the Next point of curve… prompt, pick another location in the perspective viewport.
At the Next point… prompt, hold the Ctrl key and pick a point in the perspective viewport.
Drag the mouse in the perspective viewport.
A tracking line displays, indicating that the marker is constrained to move perpendicular to the construction plane. Click the left mouse button to select the point. Notice the location of the marker in the other views.
Drag objects perpendicular to the construction plane using elevator mode
Select the objects to move.
Hold the Ctrl key and click and drag with the left mouse button on the selection set.
A tracking line will connect the point you picked to the marker, indicating the new location of the selection set.
Release the left mouse button to place the objects.
Turn off elevator mode if you have started elevator mode in error
After starting elevator mode, type NoElev, or press the TAB key twice.
Continue with picking locations.
You can start elevator mode in another location.
Multiple elevator
Press the Ctrl key and click to start elevator mode.
Change viewports, release the Ctrl key, press the Ctrl key, and click again.
A new elevator mode starts relative to the new construction plane.
Canceling elevator
Press the Ctrl key and click to start elevator mode.
Elevator from direction lock
Elevator mode can also be activated from direction lock, but only if the point can be truly 3-D.
Notes
Type a number at the command prompt to specify the elevation of the point. Positive numbers are above the construction plane, negative numbers are below.
Specifying 3-D points using 2-D input devices (the mouse and monitor) is aided with construction planes. Anything drawn in Rhino by simply picking points is always drawn on the construction plane of the current viewport.
Point filters extract individual x-, y-, and z-coordinate values from different points to create a new, composite point.
You can use point filters to pick one coordinate value at a time while temporarily ignoring other coordinate values. If you use point filters with object snaps, they extract coordinate values from an existing object so you can locate another point.
After you specify the first value, you are prompted for the remaining values.
Point filters only work when 3-D input is allowed, and you cannot start with one point filter and then apply another one.
Example
To place a point at the x-coordinate of the right end of a line and the y-coordinate of the left end of a line.
Start the Point command.
At the Location of point object prompt, type .x.
At the X coordinate of prompt, with the End object snap activated, pick the right end point of the line.
This sets the x-coordinate of the point to the right end of the curve.
At the next Location of point object prompt, type .y.
At the Y coordinate of prompt with the End object snap activated, pick the left endpoint of the line.
This sets the y-coordinate of the point to the left end of the curve.
At the Location of point object prompt, pick to place the point.
If you specified an x-value, the coordinate of the new point matches the x-value of the first point and the y,z-value of the second point.
The following filters are possible:
.x
.y
.z
.xy (.yx)
.xz (.zx)
.yz (.zy)
.wx
.wy
.wz
.wxy (.wyx)
.wxz (.wzx)
.wyz (.wzy)