This function clear the current items that are being displayed and load in the new selected file. This file can be in a compressed or gzipped form if the correct commands have been set up in the XMgf.ad file.
This has the same functionality as the above function except that gf Sets can be appended to the current objects being displayed without removing those object first.
Postscript (1) , Xfig, MIF (2) , Rayshade scenefile
Raster form output are just binary image representation of what was on the screen.current Raster file formats include:
PGM, PPM, XBM, GIF, SunRaster, PBM
Xmgf allows the user to load in previously saved viewing parameters. These files hold information on the viewing angle line width sorting etc...
Xmgf allows the user to save this information for retrieval at a later date (3) .
This function allow the user to load up there own colour map for use with the colours (not greys) this can be useful if you want to define your own colour map (4)
Following on from the last function this can be used to give the greyscale colour map a new set of colours.an example of the colour map file format is given here.
Printing in Xmgf is fairly straight forward once you have an object that you want to display in the correct orientation select the Print option in the file menu. this will popup the Printer Shell as shown in Figure 8 . This allows you to select the orientation of the image which you want to select and if it is colour or not and also the name of the printer. Clicking on ok will send it to the named Postscript printer. if anyone sends me enough info on HPGL or even adapts the Postscript.c and Postscript.h I might be tempted to add this functionality.
include the ability to change the drawing style of Object. These
functions comes in a number of forms:
The line widths offerer are 1,3,5,7,9 points with one of the following line styles SOLID,DOTTED or DASHED .
Points can also be changed to a new type chosen from this list
Xmgf offer a number of different ways to display an object by selecting different fill styles for the polygons. The fill style come from this list of styles found in the Polygon menu.
The option menu consists of a number of different setting that will
change the way Xmgf behaves. The current options are:
This reset the viewing parameters such that 2D files obtained from programmes such as edge detectors and line finders will be displayed correctly on the screen it will also line up the image primitives with a background image.
The is functions automatically sorts the polygons by depth so that when the polygons are drawn they are draw furthers from the viewing position first.
This is a technique used in computer graphics and is used to smooth out the flicker caused by erasing or clearing the screen ready to draw the next frame. This process consists of drawing the next screen on a pixmap rather than the screen and when it has finished swapping this with the current screen display. it is then possible to clear the screen without any unnecessary flicker.
This sets the focal length of the viewing camera such that the image will appear in orthographic projection.
Possible FillPatterns
This removes those polygons that are not facing the viewing position and are hence invisible. This is of course not always true as you may see the inside of a polygon even though it is facing the other direction.
Depth cueing orders the colouring of the object. Instead of the greyscale colours of each polygon being assigned by the angle the light source make with it the intensity of the polygon is set by its distance from the camera. This gives the impression that objects that are nearer the camera are lighter.
The pointsize function was described in the last section on Changing the Drawing Settings.
This allows the user to turn off and text object that are in the image.
These function are what I would describe as nice little extras. They
are not the main thrust of Xmgf but add nice little features that
make Xmgf more usable
This will reread in the files that have been loaded and appended since Xmgf started up, you will note though that Load kills all files up to that point where as append doesn't
This pops open the animation window. This is currently under development but a brief description is given here. The Animation Popup consists for a number of simple functions that can be used to make animations. Before starting your animation press the new animation button. Now move the objects to your chosen starting position. Now pressing REC will record the viewing parameters in that position. Now moving the objects in the normal way and pressing REC again will save that position. When you have finished your animation pressing the play button will cause Xmgf to run through in a loop through all your prerecorded positions and interpolate the positions of the viewing parameters inbetween these positions. currently only PLAY, STOP and PAUSE work but Animations can be Saved and Loaded and the number of Interpolations set using the Animation Speed setting. (5)
This automatically rotates the objects round by a certain amount in each axis which is determined by the settings of Autorotate Options. the defaults setting is 5 degrees for each axis. This is useful to give an overall view of an object and makes a nice demo.
This allows you to set the various steps taken in the autorotation. it is also possible to stop the rotation on a particular axis and also scale up and down the speeds of each axis. Figure 15 show the Auto-Rotation Popup.
This displays a labeled axis on the image screen to help identify the orientation of the objects.
This allows the Axis to be resized without having to quit the application. Figure 14 show the Axis size popup.
fixes the axis on 0,0,0
fixes the axis on the Centroid of the data.
fixes the axis on the Centre of the data.
Draw Axis as Box around data.
This displays a bounding box for an object rather than redrawing the complete object. this can be useful if the object you are trying to view is very complex and the rotations take a long time.
This function is related to the was the Centre buttons work on the tool bar. This button has a toggle affect and the button label will change to show which type of fixation is currently being used. Fixate on Centre will fixate on the centre of the bounding box of all the objects defined by the current autoscale setting. Fixate on centroid will fixate on the average of all the points. This has proved useful in stereo work where a few points get projected a long way out and they are of little interest.
This functions related to the last in the sense that it determines how the fixation and the autoscale works. It basically means that it is possible to autoscale and fixate on only those visible objects and not on all objects.
This is used in conjunction with 2D settings and Background-image and expands a 256x256 image up to a 512x512 image and also changes the scale settings to make the GF sets fit over the expanded image correctly.
This will display a colour selection popup similar to that shown in the control panel popups. This will set the background colour to the chosen colour. if you want to return to the default colour you will find it at the bottom of the list.
This allows the user to load up an image and put it in the background. Current formats are PGM,PPM and are displayed in only greyscale. This has proved useful for checking image processing routines and is implemented to keep compatibility with xgf.
This sets the background to the Default colour and removes any images from the background.
Display a single 3D screen the full size of the Drawing area
Displays 4 screens corresponding to Side/Font/Pan Elevations and a Perspective screen where each screen is 256x256
Display two screen that correspond to the image from two cameras slightly separated.
This function set the dithered fill function on so that coloured fill and shaded fill will be dithered. This allows more realism to be added to coloured objects.
This function allows the user to specify a section of the screen that they would like to see the polygons that are in it.
This reduces the distance from the camera to the objects.This merely halves this Dist slider in the 3D control panel.
This increases the distance from the camera to the objects. This merely doubles this Dist slider in the 3D control panel.
This empties all of the current objects from the screen this cannot be undone and files will ne to be reloαδed. (See ReRead) The same effect can be found by Loading in an alternate set.
This abandons Xmgf. No warning that you are leaving will be given.
The fonts for the labels can be changed to allow for personnal
preference and also image size and thesymbol font can be used to
display mathematical symbols. Changing the font can be through the
Attribute settings or using the font menu.