START Magazine/START VOL 3 NO 12.st/OBJDOCS.ARC/OBJDOCS.ASC

Text File | 1989-04-03 | 17.4 KB | 367 lines

         GFA OBJECT -- A 3D-Modeling Program For Use With GFA BASIC

                        by Andrew Reese, START Editor

                  Program Copyright 1988, GFA Systemtechnik
             Instructions Copyright 1989 Antic Publishing, Inc.

                               Getting Started

     GFA Object is on your START disk in the file OBJMONO.ARC along with
six module files.  (Modules are basic shapes -- building blocks for more
complex objects.)  Copy OBJMONO.ARC to a blank, formatted disk and un-ARC
it, following the Disk Instructions in your issue of START.  When you are
finished, double-click on the OBJ_MONO.PRG icon to run the program.  You
will need an ST or Mega system with a monochrome monitor to run GFA
Object.  If you have a color monitor, you will need the color version of
the program, which is on the May 1989 START disk.

     Because it's impossible to reproduce the entire GFA Object manual in
this form, what follows is a quick overview with some basic information
and a button-by-button and menu-by-menu explanation of the program's
functions.  If you wish to purchase a manual, see the instructions at the
end of this article.

     When GFA Object loads, you will see the editing screen.  This is the
screen in which you will create and edit your objects.  The main window
(the Edit Field) shows the Front View of any object, while the two small
Help Screens to the right show the Right and Top Views (and are labeled,
appropriately, as "From Right" and "From Top").  The menu bar at the top
of the screen includes Desk, File, Edit, Object, Mod+Block and Options
headings.  Below the two Help Screens are the Z-scroller, the coordinates
box and the status box.

                                  Diving In

If you are familiar with CAD-3D and Cyber Sculpt from Antic Software, you
may be a bit disorientated in the GFA Object universe at first.  In GFA
Object, the Y-axis runs vertically in the front view, the X-axis
horizontally and the Z-axis represents depth.  In the Edit Field, the
origin (0,0 point) in the X and Y dimensions is in the lower left-hand
corner of the window and the dimensions of the universe are approximately
42,000 units (pixels) in all directions.

     When you enter GFA Object, you will be in Point mode, as indicated
in the status box.  In this mode, you can place points anywhere in the
Edit Field.  To create edges, you will need to select the Edge mode from
the Edit Menu.  In the Edge mode, you can create edges by first
left-clicking once in the Edit Field.  When you do so, you will see a
question mark appear in the status box.  this indicates that you have not
finished an edge.  When you left-click a second time in the Edit Field,
you will see an edge line appear between the two points.  As long as you
are at the same Z-location as an edge, it will appear as a solid line;
move away from that Z-location and it will appear as a dotted line.

     To create a surface, select Surface mode from the Edit window and
place up to 20 points in the Edit Field; as long as you have not finished
a face, two question marks will appear in the status box.  You must
finish a surface by left-clicking on the first point you set.  You may
find it difficult to find the precise location of that first point; if
you do, move the cross-hairs near the point and then right-click.  The
cross-hairs will move to the closest point; if it's the first point you
set, left-click and you will complete a surface.

     If you try out making a few edges, you will notice in the help
screens that they are all in the same plane, i.e. at the same Z-location.
You may use the Z-scroller to change the Z-location.  Click on the double
arrows to change it rapidly or the single arrows to change it more
gradually.  If you want to change the Z-location quickly to that of one
of the points in the Edit Field, left-click on the "Z" in the center of
the Z-scroller.  The cursor will change to an open cross-hairs.  Place
the cursor over the point whose Z-location you wish to use and
left-click.  The Z-location will immediately change to that of the point.

     Alternatively, you may left-click on the Z location in the Coordinates
box.  The Z-location will disappear and you may then type in a new
Z-location.  Finally, you may use the sliders on either of the help screens
to move the Z-location roughly.  To move them, you must click and hold the
left mouse button on the slider "handle."  You can then drag it in the
direction you want to move.

     NOTE: Unlike CAD-3D and Cyber Sculpt, creating a series of connected
edges does not create a surface.  You must use the Surface mode to create
a surface that will be shaded in the Display mode.

                              Coming Up For Air

     Take a few minutes to play with the program.  You can create
surprisingly complex objects through the simple techniques you've already
learned.  Don't worry if you make mistakes.  You can't hurt your computer
by making a Frankenstein's monster of a mess in the Edit Field.  When
you're done playing, select New object from the File Menu.  When you
click on the Yes box in the confirming dialog box, all your mess will be
gone.

     Let's run down the menus now.

                                The Desk Menu

-- GFA-OBJECT Info: Displays the program information and a fascinating
little drawing routine.

-- Desk Accessories: Any desk accessories you have installed can be
accessed from the Desk Menu.


                                The File Menu

-- Load Object: Lets you load an object from saved in GFA Object format.
A bit of explanation of the nomenclature is needed here.  You will see
the term "module" used in the Menus; any object can be treated as a
module and vice versa.  Modules are intended to be small "building
blocks" (in CAD-3D, they're called primitives), from which you create
more complex objects.  You may load any of the modules that came on your
START Disk directly into the Edit Field by using the Load Object option.

-- Save Object: Saves your current object to disk with the filename
extender .OBJ.

-- Load as ASCII: Loads an object from disk in ASCII file format.  The
full file format is explained in Chapter 7.2 of the GFA Object manual.

-- Save as ASCII: Saves your current object to disk in ASCII file format.

-- Load picture: Lets you load a .PI2 DEGAS (or Doodle) format picture
file.  You must be in Display Mode first to see it, however.  GFA Object
uses the current color palette for any picture you load.  You will need
to have the Control Panel loaded as a desk accessory to change the
palette to suit the picture you load.

-- Save picture: Lets you save the current screen as a DEGAS .PI2 (or
Doodle) format picture.

-- Delete File: Lets you make room on your disk by deleting a file.

-- Drive: Lets you select the current disk drive that GFA Object will
look to for files.

-- Memory: Displays the number of points, edges and surfaces you have
used, the number still available, the amount of free memory available and
the amount of free disk space.

-- New Object: Clears the Edit Field of all objects.

-- Quit: Exits GFA Object.

                                The Edit Menu

-- Edit mode: Selects the Edit Field for creating and modifying objects.
Occasionally, when switching from Display mode to Edit mode, the large
cross-hairs will "print" on the screen, creating unwanted lines.  Simply
re-select Edit mode and the Edit Field will be re-drawn and the lines
removed.

-- Display mode: Selects the Display screen for displaying objects.

-- Point mode: Selects Point mode for placing points in the Edit field.

-- Edge mode: Selects Edge mode for placing edges in the Edit field.

-- Polyline mode: Selects Polyline mode for placing a polyline in the
Edit field.  A polyline is a series of up to 20 points continuously
connected by edges.  Remember: a polyline -- or any other edge -- does
not define a surface that will appear solid in Display mode with Hidden
line active.

-- Surface mode: Selects Surface mode for placing surfaces in the Edit
field.

-- Delete mode: Selects Delete mode to remove points from the Edit Field.
To remove a point, select Delete mode and then click in the Yes box in
the confirming dialog box.  The letters "De" will appear in the status
box.  Move the cursor near the point you want to delete (you may have to
move the Z-location so that it is the same as the point), right-click to
move the cross-hairs onto the point and then left-click to delete the
point.  NOTE:  Deleting a point will also delete all edges connected to
it.  To exit Delete mode, re-select it from the Edit Menu and click in
the No box in the dialog box.

-- Displace points: Lets you move a point in any dimension.  To displace
a point, select Displace points, then type in the amount of displacement
you want in the dialog box; pressing the Return key indicates no change.
when you have entered the values, the dialog box will disappear and the
cursor will change to an open cross-hairs.  Place it near the point you
want to displace and left-click.  The point will be displaced according
to your instructions.  You will remain in Displace point mode until you
right-click to exit.

-- Point size: Lets you choose the size of the points already placed in
the Edit Field.  Default is 1-by-1 pixel, but you can change this to
3-by-3.  Points added after this change will appear as small crosses in
the Edit Field.

-- Blend in numbers: Lets you add in numbers that identify the point
numbers, the edge numbers or both to aid you in defining an object.  This
is especially useful when defining an object by entering data manually
(see below).

-- Smooth out data: Converts all fractional point definition data to
integer data.  This will, however, prevent use of the slow mode of
displaying Hidden-Line objects (see below).

-- Enter data: Lets you define points, edges or surfaces by entering
numerical location data manually.

-- Display data: Displays the location data on the screen for the current
object.

-- Print data: Prints the location data on your printer for the current
object.

                               The Object Menu

-- Rotate object: Lets you enter values (in degrees) to rotate the object
in the Edit Field.

-- Displace object: Lets you enter values (in pixels or the currently
defined unit of measurement) to move (displace) the entire current object
in the Edit Field.

-- Change object size: Lets you change the size of the current object.
Values of less than one reduce the size of the object in that dimension,
while values of greater than one increase its size.

-- Hidden-Line: Lets you select one of three modes for displaying objects
in the Display screen: No hidden lines, quick and approximate or slow and
exact.

-- Central projection: Lets you select whether to display your object in
parallel projection or with a vanishing point (central projection), to
give a sense of perspective to the observer.  Selecting central
projection (and confirming its choice) actually changes the shape of the
object.  If you don't want to do this permanently, copy the object into
the object buffer before selecting Central projection.

-- Vanishing point: Lets you select a vanishing point for central
projection.  The default is in the center of the screen and 1,000 pixels
deep.

-- Centre of rotation: Lets you choose between the default center of
rotation (the center of "gravity," or computed center of mass of the
object) and an arbitrary center of rotation that you can select.

-- Light source: Lets you choose the location of the light source used to
shade objects in the Display screen.  Default is X=1, Y=1, Z=1, placing
the light to the left, below and to the front of the object.  Values of
X=-1, Y=-1, Z=-1 places the light to the right, above and to the rear of
the object.


                             The Mod+Block Menu

-- Load module: Lets you load a module (an object) into a special buffer
so that you can use it to create complex objects.

-- Show module: Lets you display the module in the main window to insure
that the module is the one you want.

-- Merge module: Lets you move the module into the Edit Field and merge
it with the current object.  Step-by-step instructions will appear in the
upper right-hand corner of the screen to guide you through this.

-- Object buffer: Lets you store the current object in a temporary
buffer.

-- Change over: Lets you swap the contents of the object buffer with the
object in the Edit Field.

-- Mark block: Just as in word processing, Mark block lets you select all
or a portion of the current object for later manipulation.  Again,
step-by-step instructions will appear in the upper right-hand corner of
the screen to guide you through this.

-- Show block: Once you have marked a block, it will be shown by heavy,
black points.  If you then change the Z-location, the block will no
longer be shown.  Show block restores the heavy marks so that you can see
what you've marked.

-- Block as module: Lets you place a block in the module buffer, so that
you can "copy" portions of an object back onto that object repeatedly.
Placing a block in the module buffer will replace whatever is alrady in
the module buffer.

-- Rotate block: Lets you enter rotation values (in degrees) to rotate a
marked block.

-- Displace block: Lets you displace (move) a marked block, by entering
values (in pixels or the current unit of measurement).

-- Change block size: Lets you change the size of a marked block,
similar to changing the size of an object.

-- Delete block: Lets you delete a marked block, along with all edges
running to points in the block.

                              The Options Menu

-- Set units of measure: Lets you name and define an alternate unit of
measurement, instead of the pixel used as a default.  The new unit of
measurement can be anywhere between 10 and 100 pixels in length.

-- Blend in scale: Displays a scale along the bottom and left edges of
the Edit Field.  It is on by default.

-- Blend in grid: Toggles a grid on and off in the Edit Field to aid you
in locating components of an object.

-- Help windows: Whenever you make a change in the object or the
Z-location of the Edit Field, the Help windows are redrawn along with the
Edit Field.  If you find that the time that this takes is burdensome, you
may switch off the Help windows by selecting this option.  To restore
them, reselect this option.

-- Rotate profile: Similar to Spin in CAD-3D and Cyber Sculpt, this
option lets you define a profile and rotate it around a center axis to
create an object.  This operation is like using a lathe to turn wood or
metal.  If you have an object in the Edit Field with fewer than 50
points, you may use it as the rotation template.  In any case, creating a
rotated object will replce whatever is in the Edit Field.  Be sure to
save or buffer any object you wish to keep before rotating a profile.
The screen for the Rotate profile function is self-explanatory;
experiment with this function to get a feel what it can do.  Just
remember that when you are satisfied with the settings, click on the
Rotation-parameter OK box to reach the Edit Field for the Rotate profile
function and when you have placed all of your desired points for the
profile, right-click to create the object.

-- Translate profile: Similar to the extrude function, this option lets
you "squeeze out" an object, like toothpaste from a tube.  You define the
shape of the opening of the tube with 20 or fewer points, tell the
program how many sections you want to squeeze out and how far apart they
should be.  Operation of the Translate profile function is quite similar
to that of the Rotate profile function; switch the various settings by
left-clicking on them and then click on the Translate-parameter ok box to
reach the translate profile edit field.  After defining the profile by
left-clicking to set up to 20 points, right-click to create the object.
Again, this will replace any object in the Edit Field.

-- Pic background: In Display mode, lets you load in a DEGAS .PI2 (or
Doodle) image to use as a background for your object.  (If you have
selected background in the Hidden-Line dialog boxes, you won't see your
picture.)  Be sure that you say "no" to background if you want to load in
a picture.

-- GFA-DRAFT plus \.MAC: Lets you save a two-dimensional projection of an
object as macro-data for use in the GFA Draft Plus CADD program.

-- GFA BASIC \.GET: Lets you cut part of the Display screen and save it
as a GFA BASIC Get file.  You can then load it into your program and use
the PUT command to put it on the screen.

-- Printer: Lets you choose drivers for 9- or 24-pin printers and print
out an image of the screen.

                                   Extras

     There is a separate program on your START disk called ANIMATOR.PRG;
you will also need to have ANIMATOR.CHN in the same directory to run
Animator.  These two files are contained in a separate ARC file named
ANIMATOR.ARC.  To use Animator, un-ARC ANIMATOR.ARC and then double-click
on ANIMATOR.PRG in either medium (color) or high (monochrome) resolution.

     The Animator program does two things:  First, it lets you convert
your GFA Object .OBJ files into .DAT vector files so that you can load
them into GFA Vector and GFA BASIC as objects.  Second, it lets you
experiment with animation of any object with fewer than 1,024 points.
Now, you can get a feel for how your object will look in motion.