Working in the 3D World
Because each program is unique and does things a little differently, it's up to you to get up to speed on the user interface for your product, learning about how to move around, change the viewports, and so forth. However, they all have some things in common. Each has viewports into the 3D universe, sets of mouse-selected and type-in commands and parameters, dialogs or text files where you can set options, and so forth. Let's take a look at some of the things to be concerned with.
You'll probably be using a mouse to construct and modify objects, as well as navigate your way through the 3D universe. Familiarize yourself with any special functions the mouse performs through the use of the mouse button or key combinations. In particular, look for shortcuts that enable you to manipulate frequently used controls, such as selecting axes and switching between move, rotate, and scale functions.
To modify a shape or object, you have to select it, which usually highlights it somehow to set it apart from the rest. You can select things in the typical ways, by clicking on them with the cursor or dragging a marquee around a cluster of objects. In addition, many products allow you to open a dialog box and select objects by name, type, or color, which is very useful for picking out groups of related objects quickly (especially if you've followed a good object-naming convention).
You'll spend a lot of time peering at viewports, so get familiar with their controls. Most programs provide a way to pan (slide around the viewpoint) so that you can see things that are off to one side. You can also zoom in for detail work or zoom out to see more of the scene. There may also be a zoom all control that will automatically zoom out to show you everything in the scene. This is very helpful when you're trying to locate and move wayward pieces that were imported or created somewhere away from the rest of the model.
Most programs allow you to customize your viewports, selecting where you want the top view, the left view, the perspective view, and so on to be located. You may also be able change the size of these windows in some cases. If you can't select a new viewport with a mouse click, learn the hotkeys for changing views so you don't have to resort to using a drop-down menu.
Units and Scale
3D software uses coordinates to keep track of the size and location of objects, but these numbers are extremely long and rather awkward for users to work with directly. It's much more practical to use measurement systems you're familiar with, like inches or centimeters. Because of this, 3D programs often allow users to select the type of units they want to use for measuring: English (feet and inches), Metric (meters and centimeters), or Generic (decimal numbers, but much shorter than coordinates). In addition, they may let the user choose between fractional (1/2) or decimal (0.5) display.
Just as blueprints and engineering drawings use a scalesuch as 1/8"=1'-0" or 1cm=1m3D programs often allow you to set a scaling factor as well. It's important to set both units and scale when you first start a project, and be sure you use the same ones when building other models to combine with the first. That way, you're using a consistent measurement system, and when you merge the models into a single project, they'll be the proper sizes relative to each other.
Grids and Snaps
Grids are cross-hatched lines that can be seen in the viewport and used like graph paper for determining scale when creating objects (see Figure 3.5). When you build a 3D object, part of it usually ends up on a default grid that radiates out of the origin point, in the center of the 3D universe. However, you can change the spot at which an object will appear through the use of construction planes or construction grids, which are alternate, movable planes that move the default location for new objects to other parts of the universe. These are useful when you have a large scene and are working in a particular section only, or if you want objects to appear already aligned to a particular plane.
FIGURE 3.5 Using grids and snaps: (a) Grids and snaps make the creation and alignment of shapes and objects easier. (b) Because both objects are active regardless of viewpoint, you can align objects from any perspective. (c) For creating free-form shapes or objects, turn snap off. (d) Snaps can be set independently of the grid, making it easier to handle adjustments that are smaller than the grid.
The snap feature usually is employed in conjunction with a grid and causes the cursor to snap from one position to another, usually at the intersection of two grid lines. Depending on the program, you may be able to snap to the vertices or faces on objects as well. Note that the snap setting can be different from the grid setting, which is convenient for creating or moving objects precisely without having to alter the grid setting.
It's a good idea to use grids and snaps whenever possible, because it makes your shapes and alignments more exact, and you probably will find that it makes the modeling process go faster.
Hide and Unhide
Hide enables you to make a shape or object disappear from the scene; use Unhide to make it reappear later. This pair of commands is great for clearing out mesh that you don't need to see at the present time (as well as preventing that mesh from being accidentally modified), and it makes the scene render faster, as well. Sometimes, however, you want to see the object, but don't want it to be selected or modified accidentally. That's where a command that is commonly called either Freeze or Ghost comes in.
When you apply Freeze or Ghost to a shape or object, it still appears in the scene, but you cannot select it while it's frozen. This is a very useful feature, because 3D scenes tend to get quite complex, and it's easy to pick or transform the wrong object. Frozen objects usually change color, letting you know the object is frozen so you don't get frustrated trying to figure out why you can't select it. When you want to modify the object, you can Unfreeze or Unghost it.
Grouping is a convenient way to attach a number of different shapes or objects together temporarily. This enables you to deal with them as a whole for transforms, mapping, and other operations, but still tweak them on an individual basis if need be.
Creating a group is easyjust select the objects you want, Group them, and give the group a name. In addition, some programs enable you to manipulate individual objects within a group without using Ungroup first.