Alpha_1 User's Manual

Motif3d/Viewa1 User's Manual

Table of Contents

Basic Usage

Motif3d and viewa1 are the interactive 3D viewing programs for Alpha_1 models. They are essentially the same program, but each has a slightly different usage. Motif3d is a client application for c_shape_edit and can only be run when c_shape_edit is also running. Viewa1 is an independent application and reads .a1 files as its input.

The main features of these programs are:

Motif3d Specific

Motif3d is used as follows:
motif3d [-displaymode x11]
The "-displaymode x11" option can used on a SGI machine when the X DISPLAY variable is set to a remote host that is not an SGI. Otherwise, the motif3d will use the hardware assisted GL display driver on SGI machines.

Client/Server Network Connections

Motif3d makes a network connection to a running c_shape_edit application when it starts. If no c_shape_edit application can be found, an error message is printed and the program exits. Motif3d and c_shape_edit need not be run on the same host, but that is the default. If the c_shape_edit is on a remote host, the environment variable A1SHOST must be set to the remote hostname so motif3d knows where to find the c_shape_edit. For example:
	csh 1> setenv A1SHOST another-machine
	csh 2> motif3d &

C_shape_edit Interaction

Motif3d responds to the graphical display commands built into c_shape_edit (show, unshow, etc.). See the Graphical Interaction section of the C_shape_edit User's Manual for details. For convenience there is a "Shape_edit Command..." entry on the "File" menu which allows a single SCL command at a time to be entered via a motif3d dialog box.

Viewa1 Specific

Viewa1 is used as follows:
viewa1 [-displaymode x11] files...
The "-displaymode x11" option is the same as described above. The "files" are names of Alpha_1 binary or text files. If the first object read is a viewing transformation it is used to set the initial viewpoint.

Graphics Window Mouse Usage

The mouse is used in the graphics window to manipulate the viewpoint and to manipulate the selected set of objects. The set of selected objects is relevant for some of the operations on the menus etc.

Viewpoint Manipulation

To manipulate the viewpoint hold down the middle mouse button and drag the mouse. The viewpoint is updated according the current view mode until the mouse button is released. See Viewing Control Panel for detailed descriptions of the various viewing modes.

Selecting Objects

The selected set of objects is drawn in red by default. To select an object click the left mouse button on any part of the object. This operation deselects any other objects that were selected. To add an object to the selected set, hold down the Control key when clicking the left mouse button. Clicking the left mouse on a selected object will remove it from the selected set. Clicking the left mouse away from any object will deselect everything. There is a menu item on the "View" menu to select everything.

Menus, Dialogs, and Control Panels

File Menu

The "File" menu looks like this:
The options are:
Read A1 File...
Read objects from a file and display them.
Save View Matrix
Save the current view transformation (viewpoint) in a file named mat.a1
Save View Matrix As...
Save the viewpoint in a file of the users choosing
Print the contents of the window using Postscript
Shape_edit Command...
Send a single SCL command to c_shape_edit (motif3d only)
Exit the program. Must confirm via a dialog box

View Menu

The "View" menu looks like this;
The options are:
Clear the window
Unshow the selected objects
Select All
Select everything
Viewing Parameters...
Pop up the Viewing Parameters dialog box
Preview Animation...
Pop up the Preview Animation dialog box
Thick lines
Use thicker lines (SGI only, applies to all objects)

3D Viewing Control Panel

The standard control panel looks like this:

(view external image)
There are three sections to the control panel:

Viewing Mode
The set of "radio button" at the top selects the viewing mode for interactive manipulation. Only one "mode" can be selected at once. This mode determines the actions take when the middle mouse button is dragged in the 3D viewing window.
  • Scale - Globally scale the objects. Move the mouse left (for smaller) and right (for larger).
  • Pan and Zoom - First move the point where the mouse is clicked to the center of the screen, then scale as the mouse is dragged. Scaling works the same as "Scale" mode.
  • XY Pan - Apply X and Y translations following the mouse.
  • XY Rotate - Apply X and Y rotations following the mouse. This makes the mouse act similar to a track-ball or joystick. Moving the mouse left and right rotates around the Y axis, and moving the mouse up and down rotates about the X axis.
  • Z Rotate - Rotate around the Z axis. Moving the mouse to the right causes a positive rotation, and left causes a negative rotation.
  • Hither - Move the "hither" (near) clipping plane. Objects are clipped against two planes parallel to the XY plane. Moving the mouse to the right moves the plane closer to the viewer, left moves it away from the viewer.
  • Yon - Move the "yon" (far) clipping plane.
Predefined Viewpoints
The middle set of buttons are for selecting predefined viewpoints. The first group is:
  • Reset - Set the viewing transformation to the default.
  • Center - Center all the objects in the window.
  • Selected - Center only the selected objects.
The next set of buttons are the 6 traditional engineering views (top, right, etc.).

The last two buttons are for user-defined views:

  • Save - Save the current viewpoint.
  • Restore - Restore the previously saved viewpoint.
Other Options
The last part of the panel has pushbuttons for some other options.
  • Perspective - Turns perspective on or off.
  • Continuous - Turns continuous drawing on or off. Normally, when the middle mouse is dragged, the window is redrawn continuously (as fast as possible) until the mouse button is let up. If performance is a problem, continuous display can be turned off. This will cause the window only to be redrawn when the mouse button is let up.
  • Fast Display - Turn fast display on or off. Another option when performance is a problem (default is off). The option displays all objects as a "bounding box" during continuous viewing operations to speed up the display. This can actually make things worse in many instances.
The last two performance options are rarely required on current workstations except for extremely complicated models.

Viewing Parameters

Selecting the "Viewing Parameters..." item from the "View" menu pops up a dialog box. The operations of this dialog box apply to the selected set of objects only. The options control the appearance of curves and surfaces. Once the dialog box is open, it can be used multiple times with different sets of selected objects by using the "apply" button. The dialog box looks like this:

(view external image)
The operations are described in the following:

Curve Polys
Display control polygons of curves.
Display curves as smooth lines.
Surface Meshes
Display control meshes of surfaces.
Surface Isolines
Display isoparametric lines of surfaces.
Display normals near the four corners of a surface as arrows in the direction of the normal with base on the surface. This can be useful for checking orientation of surfaces.
Display shaded surfaces (SGI only).
Crv Fineness
(5.0) Set the fineness value for smooth curve display. Smaller values will produce smoother curves (more line segments) and larger values will produce coarser representations (fewer line segments). This also affects isoparametric lines. Use the arrow, or edit the numbers directly to modify.
Srf Fineness
(30.0) Set the fineness value for the spacing of isoparametric lines in surface display. Smaller values will produce more isoparametric lines and larger values will produce a coarser representation with fewer isoparametric lines.
Apply the changes and close the dialog box.
Don't apply any changes and close the dialog box.
Apply the changes but leave the dialog box open.

Previewing Animations

Selecting the "Preview Animation..." item from the "View" menu pops up a dialog box. This dialog box allows animation previewing of group and instance structures. Every animated instance that is currently displayed will be included in the preview. The dialog box has a "VCR-like" interface and looks like this:

The top row can be used to adjust the time increment between steps, effectively changing the number of frames that are displayed. The "Number of frames:" box can be set explicitly as well. The "Loop" button will cause the animation to play continuously (when "play" is pushed). The next row are the "VCR" buttons, "rewind," "reverse play," "stop," "play," and "fast forward.". The bottom section is used to select the overall time interval. The slider bar can be used to manually change the current time.

X Window Resources

X resources can be used to configure the appearance of various elements of the user interface of motif3d/viewa1. The application name "Motif3d" is used for both applications. See the X/Motif3 Resources documentation for details.
Alpha_1 User's Manual Home Page
Alpha_1 User's Manual. Version 98.01.
Copyright © 1998, University of Utah