Chapter 8: Getting Started with Graphics

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8.1 Overview

The ANSYS program (and the associated DISPLAY program) enable you to portray almost any aspect of your model in pictures or graphs that you can view on your terminal screen, store on a file, or plot out as hard copy. ANSYS has numerous features to enable you to customize or enhance your graphics displays to suit your individual needs.

8.2 Interactive Versus "External" Graphics

Any discussion of graphics might seem to imply that you are running the ANSYS program interactively and viewing graphics images on your terminal screen. For the most part, this chapter is written for such a scenario. However, you can run the ANSYS program in either interactive or batch mode and store graphics images on a file for later viewing and processing. This process is called creating external graphics. Chapter 16 discusses the procedures for external graphics. Chapter 9 through Chapter 15 pertain to obtaining graphics displays interactively on your screen.

8.3 Identifying the Graphics Device Name (for UNIX)

When using the ANSYS program, one of the first things you must do is specify the graphics device name (sometimes referred to as the graphics driver). ANSYS requires this information to properly direct graphics instructions to your display device. The default graphics device name for most systems is X11. You can change it from X11 to, say, 3D if you have a 3-D graphics device for running ANSYS.

You must define the graphics device name before you activate the Graphical User Interface (GUI). Once you have activated the GUI, you cannot change graphics device names. Refer to the ANSYS Operations Guide for more information about using the GUI.

The best way to identify the graphics device name is to do so directly at program start-up. The ANSYS launcher includes an entry option for graphics device name under Interactive Set Up. By defining the graphics device name at start-up, you can activate the GUI immediately upon entering the ANSYS program. Alternatively, you can specify the graphics device name using /SHOW command once you have entered the program (but before you have activated the GUI).

8.3.1 Graphics Device Names Available

X11 (or X11C) and 3D are common graphics device names supported by the ANSYS program. Each of these are described briefly below.

8.3.1.1 X11 and X11C

Graphics Device Name = X11: The X11 graphics driver incorporates X-a distributed windowing system developed at Massachusetts Institute of Technology that a variety of platforms support. It provides 2-D graphics capability. The ANSYS program currently supports Version 11 (thus, "X11") Release 6 of the X-Window system.

X separates the functionality of traditional graphics systems into two parts: the X server and the X client. The server is the part of the system that controls the physical display device. A client is a piece of application software, such as the ANSYS or DISPLAY programs. A single server may respond to multiple clients. The server and client may reside on different machines connected to a network. X transparently handles all communication between server and client.

Graphics Device Name = X11C: On 2-D display devices that have more than 16 colors (more than four graphics bit planes; usually eight), the ANSYS program displays the model using light-source shading. Light-source shading means that when the model is viewed obliquely, the display appears to be three-dimensional. You can activate the extra colors using the NCPL field on the /SHOW command (Utility Menu>PlotCtrls>Device Options).

These devices also offer a 128-contour color option ("C-option"). This option allows contour displays to use the extra colors by adding more colors with a single intensity each. By default, the extra colors are used to display nine contour colors with varying intensities that simulate light-source shading. You activate the 128-contour color option by using X11C for the graphics device name on the /SHOW command.

Individual items can also be selected and displayed with varying degrees of translucency on 2-D devices. Translucent items will show black on the initial replot, since the 2-D driver generates only the visible face. The /SHRINK command (Utility Menu>PlotCtrls>Style>Translucency) will force the hardware to plot all of the faces and provide the desired translucent effect.

8.3.1.2 3D

Graphics Device Name = 3D: If you have a 3-D graphics device, you should specify 3D as the graphics device name. A 2-D device contains a "flat" 2-D projection of your model (image manipulation is performed in software), but a 3-D device contains a 3-D model in its local memory (image manipulation is performed by the display hardware). As a result, 3-D devices perform certain graphics functions in ANSYS more efficiently, and 2-D devices do not support certain functions. The 3-D functions in ANSYS include "real-time" dynamic transformation (rotation, translation, etc.) of your actual model, translucency, and control of various lighting options, including reflectance, intensity, light direction, and shading. If you are using a 3-D device, you can set certain display option modes using the /DV3D command (Utility Menu>PlotCtrls>Device Options).

8.3.2 Graphics Drivers and Capabilities Supported on UNIX Systems

The table below lists the 3-D graphics drivers and capabilities that ANSYS supports in various UNIX environments. The supported capabilities are noted with a Y in the driver column:

Table 8-1 ANSYS-Supported 3-D drivers and capabilities for UNIX

DEC OpenGL

HP
Starbase

HP
OpenGL

IBM
OpenGL

SGI
OpenGL

Solaris
XGL

Window Device

Y

Y

Y

Y

Y

Y

Hot Keyboard/Mouse

Y

Y

Y

Y

Y

Y

3-Button Mouse

Y

Y

Y

Y

Y

Y

Remote Network Access

Y1

-

Y

Y

Y

-

Hidden Line Removal

Y

Y

Y

Y

Y

Y

Translucency

Y

Y

Y

Y

Y

Y

Light Source Shading

Y

Y

Y

Y

Y

Y

3-D Local Transformations

Y

Y

Y

Y

Y

Y

Double Buffering

Y

Y

Y

Y

Y

Y

Degenerate Mode

Y

Y

Y

Y

Y

Y

1. Remote Network Access is restricted to systems that support OpenGL.

8.3.3 Graphics Device Types Supported on UNIX Systems

The table below summarizes the graphics device types that ANSYS supports in various UNIX environments:

Table 8-2 ANSYS-Supported graphics device types (for UNIX)

Platform

Device

Description

Digital Alpha (Digital UNIX), HP, IBM, SGI, Sun SPARC (Solaris)

X11 or x11
X11C or x11c

X11 Color
X11 Color contour

Digital Alpha (Digital UNIX)

3D or 3d

3-D OpenGL Graphics

HP

3D or 3d
og 1.l

3-D Starbase Graphics
3-D OpenGL Graphics

IBM

3D or 3d

3-D OpenGL Graphics

SGI

3D or 3d

3-D OpenGL Graphics

Sun SPARC (Solaris)
Sun UltraSPARC

3D or 3d
3D or 3d

3-D XGL Graphics
3-D OpenGL Graphics

1. Separate executable for OpenGL support

8.3.3.1 Unsupported Graphics Devices

The ANSYS program does not fully support the following graphics display devices:

Although these devices are still valid for the ANSYS /SHOW command, you cannot use them to access the ANSYS menu system, to pick items on graphics displays, or to access ANSYS online help.

8.3.4 Graphics Environment Variables

The following table lists the environment variables you can set before executing the ANSYS program or the DISPLAY program. Setting these variables alters the behavior of the X11 device driver and (where explicitly stated) also modifies 3-D graphics behavior.

Table 8-3 Graphics environment variables

Environment Variable

Affected Driver

Description/Example

ANSFONT

X11, 3-D

Selects a particular font.

ANSCWID

X11, 3-D

Normal ANSYS text size (percentage of standard size)

setenv ANSCWID 120

ANSCWID2

X11, 3-D

Small ANSYS text size such as node numbers (percentage of standard size), for instance:

setenv ANSCWID2 120

ANSCURS

X11

Select cursor style; for example:

setenv ANSCURS 22

ANSCREV

X11

Reverse cursor color. Used only when
ANSCURS is set.

ANSVIS

X11

ANSYS visual key; instructs ANSYS to use a specific visual.

ANS_SNGLBUF

3-D

Disables double buffering. Applies to HP and SGI 12-bit plane systems only.

8.4 Specifying the Graphics Display Device Type (for Windows)

For Windows users, ANSYS supports these drivers and capabilities:

Note-On a two-button mouse, the shift-right button functions like the middle button of a three-button mouse.

If you are running the program on Windows platforms, you have three alternatives for specifying the graphics device type: 

ansys55 -d device_type

8.5 System-Dependent Graphics Information

This section describes factors affecting how ANSYS graphics display on different hardware systems. You should read this information before you activate the ANSYS graphical user interface.

8.5.1 Adjusting Input Focus

To enable the display, meshing, and listing interrupts to work correctly, you must set the input focus in the text window from which the ANSYS program is executing. You can set the focus in either of two ways:

8.5.2 Deactivating Backing Store

When you are using the X11 graphics driver on Sun SPARC systems, backing store is turned on by default. For faster graphics response turn backing store off by issuing the command shown below: 

setenv ANSBACK 0

8.5.3 Setting Up IBM RS/6000 Sabine Graphics Adapters

For 3-D OpenGL, initialize the window manager using the command below: 

xinit -- -x abx  -x mbx  -x glx
3-D OpenGL does not apply to Sabine, GT4E, and GT0 graphics adapters.

8.5.4 Displaying X11 Graphics over Networks

You can display X11 graphics within the ANSYS program over the network if the following conditions exist:

For example, suppose that you want to run the ANSYS program remotely from another UNIX system for local display of X11 graphics on your workstation monitor. You would perform these steps:

1. Open a window on your workstation and issue the following command to authorize remote hosts to access the display: 

/usr/bin/X11/xhost +
2. Log onto a remote host (via Telnet, login, etc.). Type the following command or commands to tell the remote host to display X11 graphics on your workstation. 

setenv DISPLAY Your_Workstation:0.0

DISPLAY=Your_Workstation:0.0
export DISPLAY
3. Execute the ANSYS program and X11 graphics will be displayed on your workstation monitor: 

ansys55 -d x11 -g

8.5.5 HP Graphics Drivers

The X11 and 3-D Starbase graphics drivers are supported on the HP workstations. You must install the Starbase libraries on the system.

CRX and HCRX graphics devices can use only the X11 graphics driver, unless you have installed the PowerShade software on the machine.

If you are running HP CDE, set the colorUse option to BLACK AND WHITE. You can do so using the HP Style Manager - Color Option. The 32-bit HP (hppa7x00 and hppA8000) versions of the ANSYS executable are appended with the ogl suffix to support OpenGL graphics. These versions can only be run on HP systems that support OpenGL.

8.5.6 Producing Graphic Displays on an HP PaintJet Printer

You can produce hard-copy outputs from within the ANSYS program on a PaintJet printer when running on an HP workstation. To do so, issue this command: 

/pcopy,key
To produce a hard copy from within the DISPLAY program, use this command: 

term,copy,key
Possible values for key are:

0

Turn hard-copy option off.

1

Copy each successive display, placing them in a bitmap file named file.pjet.xx.

now

Copy the current display, placing it in a bitmap file named file.pjet.xx.

The xx is a two-digit integer between 00 and 99.

You can send the bitmap file resulting from either of the commands shown above to a PaintJet printer. To print the file.pjet.xx file, use the HP-UX command pcltrans. The format for this command is as follows: 

pcltrans -C -p file.pjet.xx > /dev/paintjet
The value /dev/paintjet is the device name for the printer. If the printer is connected to a spooler, use the following command: 

pcltrans -C -p file.pjet.xx  |  lp -oraw
The last example assumes that the PaintJet is the default output device.

Notes

8.5.7 PostScript Hard-Copy Option

When you are using the PostScript Hard-Copy option on a CRX 24 or HCRX 24 graphics board, set the environment variable ANS_SNGLBUF=1 to get a higher quality image. This variable disables double buffering. Therefore, set it only before you use the Hard-Copy option.

8.5.8 IBM RS/6000 Graphics Drivers

Both X11 and 3-D graphics drivers are supported on the IBM RS/6000 workstations in the AIX windowing environment. The 3-D driver incorporates the Silicon Graphics licensed software, OpenGL.

8.5.9 Silicon Graphics Drivers

Both X11 and SGI OpenGL graphics drivers are supported on the Silicon Graphics (SGI) workstations.

8.5.10 Sun SPARC (Solaris) Graphics Drivers

If ANSYS is not invoked from the launcher or the ansys55 script, each ANSYS user's .cshrc file must contain the following environment variable definitions in order to use the Solaris graphics drivers: 

setenv OPENWINHOME path/openwin
setenv LD_LIBRARY_PATH
/ansys55/syslib/solaris:/ansys55/lib/solaris:/usr/lib

setenv XGLHOME path/SUNWits/graphics-sw/xgl-3.0
setenv OPENWINHOME path/openwin
setenv LD_LIBRARY_PATH
/ansys55/syslib/solaris:/ansys55/lib/solaris:/usr/lib
Note-You must enter the setenv LD_LIBRARY_PATH definition on a continuous line without a carriage return.

8.5.11 Sun UltraSPARC Graphics Drivers

If ANSYS is not invoked from the launcher or the ansys55 script, each ANSYS user's .cshrc file must contain the following environment variable definitions in order to use the Solaris graphics drivers: 

setenv OPENWINHOME path/openwin
setenv LD_LIBRARY_PATH
/ansys55/syslib/solaris:/ansys55/lib/solaris:/usr/lib
Note-You must enter the setenv LD_LIBRARY_PATH definition on a continuous line without a carriage return.

8.6 Creating Graphics Displays

You can create many types of graphics displays: geometry displays (nodes, elements, keypoints, etc.), results displays (temperature or stress contours, etc.), and graphs (stress-strain curves, time-history displays, etc.). Creating any display is a two-step process:

1. You use graphics specification functions to establish specifications (such as the viewing direction, number and color controls, etc.) for your display.

2. You use graphics action functions to actually produce the display.

You can perform both types of graphics functions either by using menu functions in the GUI or by typing in commands directly.

8.6.1 GUI-Driven Graphics Functions

When running the ANSYS program interactively, most users will prefer to use the GUI. As you use the GUI functions, you execute commands without actually seeing or editing them. (The program will record all underlying executed commands in your Jobname.LOG file.) You can access graphics specification functions via Utility Menu>PlotCtrls. Graphics action functions reside under Utility Menu>Plot.

8.6.2 Command-Driven Graphics Functions

As an alternative to using the GUI functions, you can type ANSYS commands directly in the Input Window. In general, you enter the graphics specifications using the graphics "slash" commands (for example, /WINDOW, /PNUM, etc.). Graphics action commands are usually either prefixed with PL (PLNSOL, PLVAR, etc.) or are suffixed with PLOT (EPLOT, KPLOT, etc.).

8.6.3 Immediate Mode Graphics

By default in the GUI, your model will immediately be displayed in the Graphics Window as you create new entities (such as areas, keypoints, nodes, elements, local coordinate systems, boundary conditions, etc.). This is called immediate mode graphics. Anything drawn immediately in this way, however, will be destroyed if you bring up a menu or dialog box on top of it. Or, if you iconify the Graphics Window, the immediate mode graphics image will not be shown when you restore the Graphics Window icon.

An immediate image will also be automatically scaled to fit nicely within the Graphics Window-a feature called automatic scaling. Periodically, though, you may need to issue an explicit plot function because you have created new entities which lie "outside" the boundaries of the scaled image already in the Graphics Window and are thus not captured with immediate mode graphics. The plot function will rescale and redraw the image.

To obtain a more "permanent" image, you need to execute one of the plot functions (such as Utility Menu>Plot>Volumes) or a graphics action command (such as VPLOT). An image generated in this way will not be destroyed by menu pop-ups or by iconifying the Graphics Window. Also note that symbols (such as keypoint or node numbers, local coordinate systems, boundary conditions, etc.) are also shown immediately but will not be present on a "permanent" display unless you first "turn on" the appropriate symbol using the functions under Utility Menu>PlotCtrls or the appropriate graphics specification command.

If you prefer not to see things immediately as you define them, you can use the IMMED command (Utility Menu>PlotCtrls>Erase Options>Immediate Display) to turn off immediate mode. When you you run the ANSYS program interactively without using the GUI, immediate mode is off by default.

8.6.4 Replotting the Current Display

The /REPLOT command (Utility Menu>Plot>Replot) re-executes the last display action command that was executed. However, the program can execute that command only if it is valid in the current ANSYS routine. For instance, if you issue a PLNSOL command in POST1, then exit that routine and replot while at the Begin level, no contour display will be formed. To save time, you may want to define an abbreviation for the /REPLOT command so that it is available on the Toolbar as a "quick pick."

8.6.5 Erasing the Current Display

You can clear the current graphics display by issuing the ERASE command (Utility Menu>PlotCtrls>Erase Options>Erase Screen). (GUI menus will not be erased, however.)

8.6.6 Aborting a Display in Progress

If you have initiated a display and decide to terminate it before it is completed, invoke your system "break." (Typically, this means moving the mouse pointer to the Output Window and typing Ctrl+C. However, the specific procedure varies from system to system.) You must execute this break while the display is visibly in progress, or else your entire ANSYS session will terminate.

8.7 Multi-Plotting Techniques

The multi-plotting capabilities within ANSYS enable you to display both multiple entities within a window and multiple windows with varying entity types. Defining each window's composition is a four-step process:

1. Define the window layout.

2. Choose the entities you want each window to display.

3. If you are displaying elements or graphs, choose the type of element or graph display used for plots.

4. Display the entities you selected.

8.7.1 Defining the Window Layout

You need to define how many windows you want the ANSYS program to use for plotting and how those windows appear on your screen. You have the following layout options:

To define the window layout, issue the /WINDOW command (Utility Menu>PlotCtrls>MultiWindow Layout). If you choose the GUI path, the program displays a dialog box, in which you click on the layout you prefer. That dialog box also contains a "Display upon OK/Apply" field, where you also can specify what the ANSYS program displays next. Choices for this field are "Multi-Plots," "Replot," and "No re-display." When you finish specifying your layout design, click on Apply or OK.

8.7.2 Choosing What Entities Each Window Displays

Once you have designed your window layout, you choose what entities each window will display. To do so, use either of the following:

Command(s):

GUI:

Utility Menu>PlotCtrls>Multi-Plot Controls

If you use the GUI path, a dialog box appears. In its "Window to edit" field, click on either "All windows" or a specific window number (default is window 1). In the "Display type" field, choose either "Entity plots" or "Graph plots." Then, click on OK. If you choose "Entity plots," another dialog box appears, listing the types of entities available for display. (You also can choose the type of plots via the /GCMD command, as described below.) All entity types except GRPH are on by default; to turn an entity type off, click on it.

If you use the /GTYPE command, for the wn argument, either specify ALL to have all windows display the selected entities or choose a specific window number (default is window 1). For label, specify any of these entity types:

When the GRPH entity type is activated, you can display only x-y graphs, and you cannot use the /GCMD command to issue other commands (such as /TYPE) that affect displays. (For more information about /GCMD, see the ANSYS Commands Reference and Section 8.7.3 of this manual) If the GRPH type is off, you can display any combination of the other solid model or finite element entity types, and you can use /GCMD to issue other display control commands.

To turn an entity type on via the /GTYPE command, use a key value of 1. To turn an entity type off, specify a key of 0.

8.7.3 Choosing the Display Used for Plots

When you are displaying either the ELEM or GRPH entity type, you can control the type of element or graph display used for plots. To do so, use either of the following:

Command(s):

GUI:

Utility Menu>PlotCtrls>Multi-Plot Controls

You can specify ALL to have all windows use the selected display type, or you can apply that display type only to a specific window (default is window 1). The lab1 through lab12 values shown above are labels for commands such as /TYPE and PLNS,S,X. (For the lab arguments, you can specify only commands that have wn (window) arguments.)

Issuing the /GCMD command is the same as choosing the GUI path shown above, then choosing either "Entity plots" or "Graph plots" for the Display Type field.

Following are two command-based examples of selecting a type of element or graph display.

8.7.4 Displaying Selected Entities

To display the entities you selected, issue the GPLOT command (Utility Menu>PlotCtrls>Multi-Plots or Utility Menu>Plot>Replot).

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