AutoCAD Tip: Easy Zooming with Mouse Wheel

24 Aug, 2006 By: Billy Wooten

Give up the window method for more efficient navigation in your drawings

Recently, I was looking over the shoulder of one of my fellow "CADets" and saw her zooming using the window method in AutoCAD. I hadn't done that in quite some time and thought that maybe I needed to review.

Then, I remembered why I switched. Since the advent of the wheel-mouse, AutoCAD's window function has become very limited in use. Today, I just use the wheel. Here are a few tips about using AutoCAD's Zoom command via the wheel-mouse.

When you use the wheel on your mouse to zoom in AutoCAD, the focus of the zoom is where the cursor lies. Notice how the drawing shrinks and grows in conjunction with the wheel around the cursor arrow point. Combining this with the pan feature (holding down the wheel), you can conveniently navigate around the drawing as you desire.

As you turn the wheel, notice the feel of the notches as you zoom in and out. Observe this: Open any drawing. Place the cursor at the center of the screen. Roll the wheel backward one notch and then forward one notch. Notice that the view is now slightly smaller than it was before. Repeat this procedure and the view gets smaller and smaller.

Another feature I use quite frequently is the ZOOMFACTOR system variable. A small LISP routine (included as ZT.LSP below) toggles the variable from a factor of 65 (my default) to 5 (for fine-tuning). To understand the ZOOMFACTOR settings, just type Zoomfactor, enter different values from 3 to 100 and observe how it performs. (For convenience, I've set the right-click, Shift +Ctrl key combination on my menu file to execute this routine.) It's all a matter of what works best for the operator.

(defun c:zt (/ qt); Toggle Zoom Factor 5 - 65
  (setq qt (getvar "zoomfactor"))
   (if (/= qt 65)
      (setvar "zoomfactor" 65)
      (princ "\nZoom Factor = 65")
   (if (= qt 65) 
      (setvar "zoomfactor" 5)
      (princ "\nZoom Factor = 5")
Lastly, panning with the wheel provides different outcomes when used with the Shift key (orthogonal mode) or the Ctrl key (dynamic pan mode). In Windows XP, notice that panning doesn't stop when the cursor reaches the edge of the screen -- it continues past it. The Shift key must be held down constantly to maintain orthogonal mode, but the Control key can be released to maintain dynamic pan mode. I've also included a LISP routine (ZR.LSP) that performs a Zoom Extents, then backs off 5%. There's no reason for this -- it's just that some of us feel more comfortable with a little border space around the view. Both routines can be renamed so they don't conflict with your present naming conventions.
 (defun c:zr (); Zoom Room
  (command "zoom" "extents"
           "zoom" ".95x"

About the Author: Billy Wooten

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