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Michael BeallMichael’s Corner #38
February 2006

3D Orbit, Programming, and Some Useful Techniques

by Michael Beall

If it weren't for my customers, I don't know where I'd come up with all the stuff I put in this column each month! All of the topics this month came up during training at the two offices of Interior Investments in Chicago last week. [Thanks y'all!] It seems that I never have enough time to show folks 3D, so this month I thought I'd show you the fundamentals of 3D Orbit. Then we were talking about what are commonly referred to as the "shortcut" keys but that are technically called aliases. I used to go through Express Tools to do that, but I have since learned a more elegant approach. Under the general heading of "Technique", I realized that I hadn't covered the Wipeout object yet. Fabulous alternative when it comes to phasing or if you have a large drawing but you only want to view a certain portion. Another Technique item is covered in the Basics this month where I mention the ability to lock the display of a viewport in the layout.

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Blessings to one and all,
Michael

Getting Familiar with 3D Orbit

3D Orbit is essentially the Swiss Army knife of AutoCAD's 3D ability. Its most useful feature is the ability to position your eyeball so you can get the most advantageous point of view. Several versions ago the 3D Orbit tool used to be on the Standard toolbar, but now it has a toolbar all to itself. Please note, the fluid manipulation of the objects when using 3D Orbit is directly related to the power (ie, RAM) in your computer. You can't climb the Alps without the proper equipment, likewise with your use of 3D Orbit. Just try to conquer what you are equipped to confront.

Quick 3D Object

In case you don't have a 3D drawing laying around (and rather than using the monstrous 3D examples in AutoCAD's Sample folder), begin a new drawing and do the following steps to create a simple 3D shape:

  1. Create a 12 x 12 rectangle
  2. From the Draw menu, go to SolidsExtrude
  3. Enter 18 as the height for the extrusion
  4. Enter 10 as the taper for the extrusion

Here are the features that will equip you to more effectively "play" with 3D Orbit.

Setup

My first recommendation would be to isolate the objects you want to view in 3D by putting them in a separate drawing. Since I work primarily with contract furniture dealerships, many times they simply need to view a cluster of workstations so the customer gets an idea of their work environment.

The "Beach Ball"

Click the 3D Orbit tool and you get the green "arcball" (an Autodesk term) centered in your drawing. Think of it as a giant beach ball with your 3D objects inside and this will go much easier. When you position your cursor inside the beach ball, it becomes a double-banded little sphere.

Think of placing the palm of your hand on the front of the ball with the cursor. Move your hand up (pick and drag up) to essentially "roll" the ball away from you, the objects go with the ball and the objects near the bottom of the display roll up toward you. Reposition your cursor to another location on the ball and roll it by dragging your cursor. Pick, drag, and roll. Go slowly, it's pretty sensitive.

The Shortcut Menu

While the ball is displayed, right click to display the shortcut menu. As you're getting used to manipulating the ball, it may be helpful to use one of the many items under Preset Views. If you get lost, use "Top" to return to your top (or plan) view.

Another Cursor Option

There is another cursor-related feature in 3D Orbit that will help you in positioning the 3D view. If you position your cursor outside the ball, you see an icon which is a sphere with a circular arrow around it. Think of the green circle as a platter in this instance. Click and drag your cursor around the outside of the platter to simply take the view and dynamically rotate it around. It's like straightening a picture on a wall. You're not repositioning your eyeball in 3D, you're rotating the image two-dimensionally.

Viewing Options

There are several Shading Modes in 3D Orbit, all of which stay enabled, even after exiting 3D Orbit. I mention this because I have received drawings that display with hidden lines when you open them up. So remember to return to the Wireframe mode prior to exiting the 3D Orbit feature. Hidden may serve you best as you manipulate the 3D objects. And if you use the Gouraud Shaded mode, you get a really nice image whose colors are based on the layers of the 3D objects.

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Power Tool

Command Aliases

Do you want to change "C" to mean Copy rather than Circle? Do you use "R" for Redraw anymore? Set it to Rotate! Veterans will recall that the file containing these "aliases" is called ACAD.PGP (Program Parameters file). And some of the rest of us know pieces of how to do this, but let me pass along something I learned at CAD Camp last year and that was reiterated at Autodesk University: Put your desired aliases at the bottom of the acad.pgp file!

Here's why: Since AutoCAD reads the list of aliases in that file from the top down, if C means Circle early on in the list, and when it gets to the bottom you have it set for C to mean Copy, it supercedes the setting for Circle!

This works for all versions of AutoCAD, even LT! In the following exercise, I'm giving you the steps for editing this file using A2006. AutoCAD 2005 is similar. If you have earlier versions, I would recommend you use the Windows Find routine to find acad.pgp, then open it in Notepad.

Note: Yes, you could use the Express tool for editing the alias, but the following procedure retains the integrity of the original list while enabling you to make your desired settings.

Instructions to Modify Your Command Aliases
  1. From the Tools menu go to CustomizeEdit Program Parameters (acad.pgp). This will open the file in Notepad. More importantly it will open the appropriate file which is located, by default, in a folder far, far away.
  2. Scroll all the way to the bottom of the acad.pgp file. In A2006 you may have a heading and a note regarding User Defined Command Aliases. This is where you need to be.  All other acad.pgp files will just come to an end, probably after the alias assignment for Zoom.
  3. Set your aliases using this context:

C,         *COPY

First, enter the characters you want to type at the command line to launch the command, followed by a comma.

Now, put in a few spaces, then precede the command to be launched with an asterisk and enter the full name of the command. Here are a few examples that I have added to my own acad.pgp

3,         *3DORBIT
Q,         *QSAVE
R,         *ROTATE
RR,       *RECTANGLE
WW,     *WIPEOUT
CC,       *CIRCLE

  1. Save your acad.pgp file and close Notepad.

So there you are, ready to test your new aliases… and they don't work. That's because the acad.pgp file is accessed when AutoCAD launches. Unless, of course, you would like to force AutoCAD to look at it now that you have made these changes.

Instructions to Make Your Aliases Take Effect - Now!
  1. At the command line, enter REINIT to open the Re-initialization dialog box.
  2. Check the box for PGP File, then click OK.
  3. Test your new alias(es). Have a nice day.

That dialog box has been there since Release 12. Seriously!

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The Odd Spot

Wipeout

A Wipeout object is a glorified 3D face; a 2D solid. Curiously, when you select a wipeout object and open the Properties window, it's listed as a Raster image (the reason will be forthcoming). The Wipeout command used to be in the Express Tools, but beginning with A2005, they moved it (more like buried it) to the Draw menu. It has no presence on the Draw toolbar, just in the menu. To see the power of this feature, I'm going to open the A2004/A2005 Sample drawing called 8th Floor Furniture. It is a furniture drawing containing an Xref as the base plan.

Instructions to Create a Wipeout Object

  1. Create a polyline (on the desired layer) around what you want to "cover" with the wipeout object. You will need to use the Close option of the Pline command for the wipeout to work.
  2. Launch the Wipeout routine, then press [Enter] to accept the <Polyline> option.
  3. Select the existing polyline.
  4. When prompted to "Erase polyline?", enter Y (the wipeout object has its own Frame).
  5. Don't panic. You have effectively converted the polyline to an opaque wipeout object "covering" the objects.

Wipeout Options

"Specify First Point" - If you didn't draw a polyline first, the default procedure for the Wipeout command is to specify points for the wipeout object. The shape is closed by default, you just pick the points.

Frames - This is why a wipeout is technically considered to be a raster image: you can toggle the wipeout frame on and off with the Frames option or the Tframes variable… which also works on raster images.

Instructions to Bring a Block or Xref Above the Wipeout

  1. To turn Off the wipeout frame, launch the Wipeout command, then enter F from Frame, then OFF.  Alternatively, you could type TFRAMES.
  2. From the Tools menu, click Draw OrderBring to Front, then select the Block or Xref to bring above the wipeout.

Cool Wipeout Features

Select objects below the wipeout - With no command current, window the area where the wipeout has been created. You will see the objects (along with the grips) covered by the wipeout.

Adjust the wipeout shape with grips - Turn on the wipeout frame, then click the wipeout frame to display the grips. Take a grip and reposition it to another location. Move the entire wipeout to another area of the drawing to get the feel for how the wipeout works.

Odd Spot October 2005 Follow-up

Q: Robert Thornberry just emailed me regarding the "Inches Only Dimensions" article I had in the October Odd Spot. He noted that although the inches suffix I recommended… "… is great for non-angular dimensions, what about angular dimensions which will now display the inches suffix after the degree sign of the angle? Good catch!

A: The only solution I know that would be effective on an ongoing basis would be to create a new dimension style for angular dimensions. This could be done by starting with the Inches Only dimension style, then either making a New one or by using the Override button, then renaming the <style override> item after making the necessary edits. In either case, you will have a separate dimension style that can be selected from the shortcut menu of a selected dimension or from the dimension style list of the Dimension or Styles toolbars. Needless to say, this new dimension style would be great to have in the template.

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The Basics

Locking the Viewport Display

After you have created a viewport in the Layout and set it to the desired plot scale (i.e., 1/8" = 1'0") from the dropdown menu of the Viewports toolbar, how can you keep from mistakenly changing the plot scale when you scroll in the viewport.

Instructions to Lock the Viewport Display
  1. While in the Layout, single click on the viewport frame, then right-click and go to Display Locked, then slide over and click Yes.
  2. To prove that indeed the display is locked, double-click inside the viewport to make it current.
  3. You will notice that the plot scale of the viewport shown in the Viewports toolbar dropdown list is grayed out. That's your first indication that the viewport is locked.
  4. Use your wheel mouse or the Pan or Zoom commands. You will notice that the entire layout may pan or zoom, but not the display of the objects as they relate to the viewport.

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Left Field

Donald Duncan In addition to popularizing the Yo-Yo, Mr. Duncan also is responsible for the invention of the parking meter and putting the Good Humor bar on a stick! The things you learn from radio!

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