3. Interaction

3.1. Starting Crafter

The simplest way to start Crafter is to type crafter from a shell window. First Geomview will start up with its three windows. Then Crafter's main window will appear (the lower-right of the windows below).

Geomview is used only to display the model and let you look at it from different angles. Crafter windows handle all editing of the model.

3.2. Command line options

When starting Crafter, you can specify a file name on the command line. For example, typing:

    crafter voyager.cr

will load the file voyager.cr if it exists. Otherwise, voyager.cr will be the name of the current file once you save it. If more than one file name is given, then the first file is loaded the normal way, and subsequent files are merged with the first one.

Other command line options available are:

-c command: read Tcl commands from the command line. For example, to start Crafter with highlighting on, type
crafter -c "SetProps Model0 {highlightsel 1}"
Multiple commands may be specified by separating them with semicolons (;).
-f filename: read Tcl commands from a file. Example:
crafter -f startup.tcl
In a file, commands may be separated by newlines or semicolons (;).
-p pipename: read Tcl commands from a named pipe. If no path is given, the pipe is put in /tmp/geomview. Example:
crafter -p mypipe
Commands are read from the pipe /tmp/geomview/mypipe.
-noui: do not display the user-interface. This doesn't make much sense without the -c, -f or -p option.
-nogv: do not display the model in geomview

3.3. Overview of Geomview

Crafter is an external module to Geomview. That means that Geomview starts Crafter as a separate process and communicates with Crafter through standard input and standard output. Theoretically, the only of Geomview's windows you need to be concerned with is the camera window. However, knowing a little more about Geomview may help you understand why things behave the way they do. It will also give you a better understanding of how to customize Crafter.

Geomview windows

When Geomview starts up, it has three panels. The panel on the left is Geomview's main control panel. The skinny panel in the middle is the tools panel and is for selecting different kinds of motions. The window on the right is the camera window, which is used to display the Crafter model.

Main panel

The main panel consists of a menu bar and two important lists: the list of Targets and the list of External Modules.

The list of targets contains all the objects that Geomview currently knows about. When you are using Geomview with Crafter, the list should look like this:

[g0] World
[g1] Model0
[c0] Camera

Model0 is the entry for the Crafter model. Geomview treats the entire Crafter model as one object. World corresponds to all the currently loaded objects, treated as if they were one object. Camera refers to the camera window on the right. While using Crafter, it is safe just to keep World selected as the target object.

The other list is the list of External Modules. When using Crafter, this list should contain at most three lines. It should look something like the following:

Crafter
[1]Crafter "voyager.cr"
Crafter "voyager.cr"

The red line starting with a number in brackets represents the Crafter process running. Clicking on this entry kills the Crafter process. The other two lines allow you to restart Crafter. Be careful.

Tools panel

The Tools panel allows you to change the type of motion you get when you drag the mouse in the Camera window. It also has other operation that allow you to change the camera angle without changing the mode of motion. The most common motion modes you might want to use with Crafter are:

Rotate
- dragging left mouse rotates object in direction of drag.
- dragging middle mouse rotates object around axis perpendicular to the screen.
Translate
- dragging left mouse translates object in direction of drag.
- dragging middle mouse translates object in direction perpendicular to the screen.
Cam Fly
- dragging left mouse rotates camera in direction of drag.
- dragging middle mouse translates camera perpendicular to the screen.
Cam Zoom
- dragging left mouse changes camera's field of view.

Other common operations that do not change the motion mode are:

Stop
Halts all motion (from inertia).
Look At
Moves the camera to a position such that it is looking at the target object.
Reset
Stops all motion and causes all objects to move mack to their home positions.

Camera window

The camera window is the most important Geomview window if you are using Crafter. The commands in the Tools panel can be invoked by typing their keyboard shortcuts in the camera window. The left and middle mouse buttons have different effects depending on the current motion mode. But no matter what mode, the right mouse button is used to select objects in the camera window. A double right click on an object makes that object the target object. Since when using Crafter the only object is Model0, double clicking is not very useful. However, a single right click over a part of the model tells Crafter to select that part.

See the Geomview manual for more information about its features.

3.4. Basic Interaction: The Model Editor

Crafter's main window, the Model Editor, displays the overall structure of the model and allows you to edit it.

3.4.1. Hierarchy list

The main part of the Model Editor is a scrolling list showing the model's hierarchy. The topmost entry in the list contains the name of the model. If it is a new model, this will be the only entry in the list. Otherwise, each entry contains the name of a piece of the structure followed by the type of piece it is. The indentation represents its place in the hierarchy. The best way to understand this is with an example. In the previous figure, Voyager is the name of the model. Dish (a parabolic dish) and Base (a cylinder) are at the top-most level of the model. Truss is attached to Dish. Bottom cap, Right and Base 2 are attached to Base. And so on.

As you probably noticed, what's in parentheses after the name of the piece is not just the type, or class, of the piece, but also a number. Actually the thing in parentheses is the address of the piece. An address is a unique identifier for an object, assigned to the piece by Crafter, and may be different each time you run Crafter. It consists of the class name followed by a number with no spaces in between. The name of the piece, also called its long name, can be any string you want. It may contain spaces and does not need to be unique. The long name can be edited in the General Properties Panel described later.

3.4.1.1. Selection

Crafter allows you to select objects from this list for doing editing operations. To select a single object, click on its entry in the hierarchy list. To select multiple objects, drag the cursor over the region of the list you want to select. If the items you want to select are not contiguous in the list, press the control key along with the left mouse button to add to the selection without first clearing the existing selection.

Another and perhaps easier way to select an object is to click the right mouse button over the object in the Geomview window. The piece of the model that is directly under the cursor will be selected in the hierarchy list.

Note that when the cursor is over a properties panel (general or class-specific), the current selection automatically changes to the object represented by the panel.

3.4.2. Navigating in the hierarchy list

Navigating the hierarchy list is made easy with the arrow keys. The up and down arrow keys move the selection up and down the list. The left arrow moves the selection up in the list to the parent of the currently selected object. If more than one object is selected, then the topmost selected item is considered to be the currently selected item while using the arrow keys.

In the previous example, Base 2 (Cylinder1) is selected. Pressing the left arrow key moves the selection to Base (Cylinder0)

Pressing <ENTER> in the Model Editor window is like double-clicking on the current selection; it brings up the General Properties Window (described later) for the currently selected object(s).

3.4.3. File name

In the title bar of the Model Editor is the name of the current file being edited. If you save the model without specifying a new name, this is the name that will be used.

3.4.4. Menus

Across the top of the window is a menu bar with menus for file operations, edit operations and creating and attaching objects. All menus can be torn off and posted as separate windows. In a posted menu, the items are invoked simply by clicking on them. This is particularly useful for the Create menu, which allows you to create and add objects to the model. To tear off a menu, post the menu as you would normally, but instead of selecting a menu item, select the dashed line at the top of the menu. This creates a separate window of menu items that is available at all times.

3.5. Creating and attaching objects

The Create menu contains a palette of spacecraft pieces, or primitives, that may be attached to the model. It may be useful to tear off this menu if you are using it a lot.

To create and attach a new object, first you need to decide which existing object you want to attach it to, or if you want to make it a top-level object in the model. Select the parent object's entry from the hierarchy list in the Model Editor, or select the (Model0) entry if you want it to be at the top level of the model. Then from the Create menu, select the class of object you want to attach. A new object will appear in the model displayed in Geomview, a new entry will appear in the hierarchy list, and a window called the General Properties Panel will pop up. This panel controls properties such as scale, rotation, transformation and appearance.