Introduction

This document is intended to be an introductory guide for those users that have never used Xmgf before, it is not intended to be a completely thorough reference manual.

This document will also not give any kind of information on the concepts of computer graphics or X11.Motif programming there are many excellent sources for this kind of information.

Getting Started With Xmgf

Windows programming to all intension purposes should be straightforward easy to use and really not need a manual. Therefore I suggest that the best why to use Xmgf is to run it. You can run Xmgf in a number of ways.

> Xmgf -u or > Xmgf -h

will bring up a list of options that can be run with Xmgf. A list of theses options is given here and a more detailed explanation will be given later.

> Xmgf -u

usage:
Xmgf [options]
-a Rotation Guide
-b Background Image (defunct)
-c [filename] Command file (see manual)
-d AutoCommand Usage
-e AutoRotate
-f xgf Automatic Colouring
-uh This message
-i AxisType 0 1 2
-j AxisColour 0 1 (default =1)
-k OrthoGraphic Projection (Focal Length > Inf)
-l 2D settings
-m Main Panel
-n No Icon panel at side
-w max displacement default=1000
-A [parameterfile] Read Parameter file
-B Polygon Sorting
-C User Colour Selection
-D PointType (Select Point type)
-E Expand Background Image
-F FillType (Select FillType)
-G Load file(s)
-H Resolution of Circular Objects
-I Origin On
-J LineStyle (0=Solid 1=Dot 2=Dash)
-K Tesserlation Value
-L Labels
-M Add Centroid
-N Double Buffering
-O Orthographic+ Perspective
-P PolyApprox (PointSet)
-Q BackFace Culling
-R User PointType Selection
-S Stereo (defunct)
-T LineWidth (Select Line Width)
-U PointSize
-V Postscript Orientation (Set= LandScape/ Default= Portrait)
-W UserScaleFactor
-X Axis
-Y DepthCueing
-Z AxisSize
Running Xmgf without any options

> Xmgf

will bring up the main panel as shown in Figure 1 . alternatively you can run Xmgf with a scenefile as an input or even multiple scenefiles.

> Xmgf -G inputfile

> Xmgf -G inputfile1 inputfile2 inputfile3.....

These commands will also bring up the Main panel but will also autoscale and automatically draw the objects. Xmgf interface is made up of a number of different work areas:

the main Panel as shown in Figure 1 has7 different rows

The current file displays the current working files, the tool and menu bar are the buttons to various functions and the Drawing area is where the 3D objects will appear. One of the buttons in the tool bar is labeled 3D panel and another Control

Figure 1 , Xmgf Main Panel

panel. The 3D panel button will pop up the 3D panel work area see Figure 2 and the control Panel button pops up the Control panel work area see Figure 3 .

The 3D panel control the viewing parameters of the 3D display the three Dials represent the rotational angles around the 3 axes X,Y,Z. The first 3D sliders are the 3 dimensional offsets of the fixation point of the viewing camera and the next two sliders are the distance and the scale of the objects. The values of the angles can be changes in a number of ways firstly by moving the arrows around or alternatively by clicking the mouse on the Angle Values widgets. This will cause an angle popup to appear and an angle can be entered into the command box and changed selectively.

Figure 2 , Xmgf 3D Panel


The control Panel is a little more complicated and is mainly used for those people who want to use the set information. For people displaying the example files such as Head.gf or Beatle.gf the panel will not be particularly useful. It is mainly used here at surrey to look at individual lines or edge strings which are the output of edge detectors and line finders you might like to look at CannyStrings.gf to see where the real power comes into play.

Figure 3 , Xmgf Control Panel

Different sets can be selected from the set list on the far right hand side and the functions in the lower box will react on only the selected set. Most of these functions consist of popup of their own but some explanation will be given for the remaining buttons.

Draw All Sets and Remove Sets are fairly obvious, Name displays the name of the current set and Set # is the number of the current selected item within the current selected set. The Next and Previous buttons step through the current selected set and highlight the current selected item. Highlight colour will bring up the popup where you can select a new colour from the list. Origin and Origin colour are related to the ID functionality of the gf format and is explained in more detail in gf.amn Its main function is the ability of one set to point and highlight item from another sets. This is particularly used when looking at what edge strings contribute to what lines in a line finder. Draw Selected Set and Remove selected sets allows you to draw and remove single sets from what is currently being drawn. Set Colour, Set Line Type, Set Point Type and Set Fill Style will change the attributes of each individual set. rather than on every set in the drawing. To speed up the use of Xmgf a separate Icon Panel has been added. the tool bar is available either on the main panel and/or from a push button on the tool bar. These functions are identical but are make available in both ways to encourage their use. Figure 5 show the icon panel. The functions on this panel are the same as those on the menus. A description is available for each icon by moving the mouse over the buttons which activates a description of the button to be shown in the Message Area at the bottom of the Main Panel. if the function is a toggle action such as Double Buffering, Depth Cueing or Sorting the these will be shown selected or deselected.

1 , Xmgf File Operations
Xmgf file operations, and there are a lot, all use the same form of file selector as shown in Figure 6 . Xmgf has a good interface with the output world and these functions are described here.


P.Hoad@ee.surrey.ac.uk
13th July 1994