Amiga MA Magazine 1998 #6/amigamamagazinepolishissue1998.iso/www/breed/files/tkgobj.doc

Text File | 1997-10-31 | 24KB | 526 lines

Designing a vector object
=========================

Each vector object in Alien Breed 3D II is made up of
one or more smaller objects.  These smaller objects
are each made up of a number of polygons which are
defined as a set of points.  For example a simple cube
would require only one of the 'smaller objects'
consisting of six polygons defined around eight points.

The following is a simple tutorial to show you how to
define a simple object, in this case the cube mentioned
above.  These simple objects are designed using the ObjEd
program, the AnimEditor will be described later.  As both
of these programs were written using Amos Professional 2.0,
if you wish to switch back to workbench at any time after
you have started the program you can do so by pressing
the 'Left Amiga' and 'A' keys simultaneously.  Switching
back the program is achieved by the same process.  This is
true of all the support programs that come with The Killing
Grounds.


Part I - Objed
--------------

Double click on the ObjEd icon to run the object editor.

The main screen is divided into four sections, three with
gridded areas, one without.  The three gridded areas are
orthographic projections, whereas the fourth area is a
perspective view (if you don't understand these terms,
don't worry, all will become clear).

The top left window shows the view from above
The bottom left window shows the view from infront
The bottom right window shows the view from the left
The top right window is alterable to show the view from
any direction.

The first step in designing an object is to put in the
points.  The program starts off in 'add points' mode, it
should say this in the bottom left corner of the
perspective window.  You can change back to the add points
mode by pressing the 'a' key or by selecting 'add point'
from the mode menu.  Note that because the right mouse
button is used to speed up the editing process, holding
it down will only access the menu if the mouse cursor is at
the top of the screen.

Now let's add some points.  This is done by clicking the
left mouse button in any of the three orthographic
projections.  The coordinates of the point will be those
shown in the bottom right of the perspective window.  As we
are desiging a cube, add four points, in a square shape
in the overhead view (top left window) at roughly the
coords (-32,0,32) (32,0,32) (32,0,-32) (-32,0,-32).  These
points will appear in the other three windows aswell.

We want to make a cube, so we need to add another four
points either above or below the first four.  The easiest
way to do this is to move all the existing points and then
add the new points where the old ones were.

Press 'm' or select 'move point' from the 'mode' menu to
change to 'move point' mode.  In this mode you can select
one or more points and move them around simultaneously.
To select a point, click the right mouse button (the
nearest point will turn red indicating that it has been
selected), now, holding down the shift key, select the
remaining points.  As we wanted to select all the points it
would have been quicker to hold down the right amiga key
and press 'a' (a shortcut for 'select all' in the 'edit'
menu).

The selected points can be moved by holding down the left
mouse button (in any of the orthographic projections) and
moving the mouse until the points are in the desired
position.  The coords displayed in the bottom right corner
of the perspective window are those of the first point
selected.  Move the points until the y coord is 64.  Now
change back to 'add point' mode by pressing 'a' or
selecting 'add point' from the 'mode' menu and click with
the left button over the top of the four points in the
overhead view.  You now have the eight corners of your cube
defined.  Next comes the complicated bit.

In order for TKG to run quickly, a few restrictions had to
be placed on the design of vector objects, these
restrictions are detailed below, but for now all you need
to know about is the polygon definition order (read it
below).  To change to 'new polygon' mode press 'p' or
select 'new polygon' from the 'mode' menu. Bearing in mind
the restrictions given below,  the faces are added to the
object by clicking on each of the points of the face in
turn, ending with the one you started with. If you make a
mistake and click on the wrong point, you can cancel the
definition so far by clicking the right mouse button or by
changing mode.  If you accidentaly complete the polygon
(missing out a point, or putting an incorrect point in) you
can delete it by changing to the 'select face' mode (press
'f' or select it from the menu).  Use the left and right
cursor keys to select the face you wish to delete (it will
be highlighted in green and drawn solid).  Now press 'd' or
select 'delete face' from the edit menu.  Return to 'new
polygon' mode and continue defining the faces as before.
Note that you can also use the perspective window for the
purpose of defining polygons.  The perspective view can be
moved around by holding down the 'alt' key and either of
the mouse keys while the cursor is over the perspective
window.  The mouse keys have different effects, the right
mouse button will show the object as it normally appears
when editing, the left mouse button, only shows the visible
polygons (so if you haven't defined any polygons, the view
will turn black).

Once you have defined your object, you can view
it in its simplest form by pressing 'v', click a mouse
button to cancel and return to the editor.

Now that the object has been defined the textures have to
be added.  Change to 'select face' mode and select the
first face.  Now press 't' to add a texture.  If you have
only just  installed the program onto your hard drive, then
you will have to define the directory containing all the
textures you wish to use.  These should be in the
graphics/textures/ draw where you installed the editing
programs, but you can put them wherever you like.  Once you
have selected this directory, the editors configuration
will be saved to a file in your s: directory.

The additional screen that is displayed at the bottom of
the editing screen is split into three sections.  On the
left is the texture (if you wish to design your own
textures, see the limitations below), in the middle is the
texture after it has been squashed into the shape of the
polygon, and on the right is a list of shortcut texture
positions.

The position of the texture on the polygon is defined by
moving the points on the texture at the left of the screen.
Pressing 'a' will make the computer attempt an 'auto-fit',
this tries to squash the polygon shape onto the texture
(with varying degrees of success).  Each point can be
individually moved by moving the mouse pointer over it and
holding down the left mouse button, pressing the right
mouse button whilst still holding down the left mouse
button will return the point to its original position.  As
you drag the point around, you will see the result on the
polygon to the right. The polygons usually look better if
you make the shape of the texture map the same or similar
to that of the polygon, to see how much distortion may
occur, hold down the 'r' key, this will rotate the polygon,
if the texture appears to bend and warp, that is probably
what will will happen in the game.

If you want to use the same texture positions on several
polygons you can save the texture positions by pressing
shift and one of the function keys, you will be asked to
type in a name for this texture definition and the settings
will be saved to your s: directory.  You can recall these
settings by pressing the corresponding function key.

There are other settings available for polygons which are
displayed above the texture map area.  The first is the
polygon brightness, this is a value from 1-100 indicating
the brightness of the polygon.  To change this, press 'b'
and type in the new value.  Next is gourade shading, this
can be toggled on and off by pressing the 'g' key.  When
gourade shading is on, attempts are made to shade the
polygon along with adjoining polygons to make them appear
smoother.  The next option is glare.  This is special in
that it has special textures defined for it.  Glare is
toggled on/off by pressing 'l'.  When a glare polygon is
drawn, it alters the colour of the pixel already on the
screen (making it either darker or lighter).  Colour zero
does nothing to the existing colour (transparent), then the
colours 1-16 go from very bright to slightly brighter than
the original colour, and 17-31 go from slightly darker to
much darker than the original colour.  This enables you to
do the strange 'light through mist' lighting effects.  The
final option is transparency, this simply takes any colour
in the texture that is 'black' (i.e. red=0 green=0 blue=0)
and doesn't draw a pixel there.  This enables you to do
grills with holes in, vent fans, etc.  This option is
toggled on and off using the 't' key.  Once you have
finished texturing this polygon, press 'esc' to return to
the main editor.

This has to been done for each polygon on the object.  When
you have finished you can save the object by pressing 's'
or selecting save from the 'project' menu.  As a
suggestion, put the extension '.obj' on the end of the
filename to help distinguish it from other files.  You need
not bother making a special directory for you objects as
the AnimEditor will do it for you later.  If you need any
additional help, there is an on-line help facility
available by pressing the 'help' key.


Part II - AnimEditor
--------------------

If you want to see the vector object you designed in part
one of this tuorial in the game, you first have load it
into the animation editor and convert it into the correct
format for the game.  Double click on the AnimEditor icon
and wait for the program to load.  The main editor screen
looks and operates in a very similar manner to that of
the object editor.

To load in your cube, or any other object either press 'l'
or select 'load object' from the project menu.  Select the
object you wish to load, and it will be loaded and
displayed on the screen.  To write this file out in the
format that is required by TKG press 'w' or select 'write
incbin' from the project menu.  The name write incbin
is left over from the very begining of Alien Breed 3D when
the vector objects were an included binary file, needless
to say the files are now loaded in.

When you press 'w' you will be presented with a file
requester in which you should specify the name of a file
for this binary file.  You will be asked if you wish
repeated and unused points to be removed.  The advantage
of removing points is speedier rendering times in the game,
but you can lose sharp edges between objects the have
adjoining gourade shaded polygons, and the points are only
checked for collision in the current frame, so if two
points are in the same place in the current frame of
animation but not in others, they may be removed, causing
the object to bend and strech.

If you decide to remove the extra points, the project must
be saved, so that it can be restored afterwards.  Simply
enter a name for the project and it will be saved.  Note
that a project actually consists of a directory of the name
you specify containing a file 'project' containing
information about the project itself.  When saving for the
first time, you will be asked if you wish to move the
objects in the project into this new directory, this is
advisable, because your hard-drive will quickly become
cluttered otherwise.


Part III - Animating a Leg
--------------------------

I have designed three simple components of a leg, saved as:

   UpperLeg.obj
   LowerLeg.obj
   Foot.obj

Load these three objects into the AnimEditor and I'll take
you through the simple steps involved in animating it.

To start with, the view looks a little cluttered, this is
because the three objects have been loaded atop one
another.  Select the lower leg, either by clicking near
it with the right mouse button, or by using 'n' and 'p'
(next & previous) to cycle through the objects.  If you're
not sure which object you have selected, press 'i' for
additional information.

Using the view in the lower right window (side view) move
the lower leg up and to the right of the foot, out of the
way, by holding down the left mouse button over the lower
right window and moving the mouse.

Now do the same with the upper leg, moving it above and to
the right.  that has cleared things up considerably.

Rotate the perspective view throught 90 degrees by holding
down the left mouse button and moving the mouse so that
the view is similar to the one directly below it.

Press the '=' key to zoom in a little, and use the cursor
keys while the mouse pointer is over the bottom right
window to centre the view again.

Now that we have our three leg parts, we want to attach
them together at the knee and ankle.  Press 'c' or select
'connect objects' from the menu to change to that mode.
When two objects are connected, the childs axis is placed
at the same coords as a specified point relative to the
parent.  This point must be a point defined in the object
editor, although it need not be used in any polygons.
Such points are removed if the option is requested when
writing out the file for TKG.

Select the foot object (the child) by clicking the right
mouse button near it's centre.  The foot wants to be joined
to the left-most ankle point of the lower leg in the front
view (lower left window).  This is done by clicking on it
with the left mouse button.  If you want to use the
perpsective window, you can, additionally, using the right
mouse button to rotate the view will reveal all the points
available for connection.

When you connect the objects together, the child will move
to it's joined position with it's parent.  If you connect
the foot to the wrong place, you can disconnect the object
again by pressing 'd' while it is still selected, then try
again.  Now select the lower leg and connect it to the
left-most point at the bottom of the upper leg.  This
forms the knee and completes the leg.

Change to 'move object' mode by pressing 'm' or selecting
the option from the mode menu.  Now selet the upper leg by
clicking the right ouse button near its centre.  If you
have a faster computer (a bit of fast ram will do) you can
select the 'Update is Quick' optin from the 'view' menu, it
should change to 'Update is Informative'.  You can do this
on a slower A1200 aswell, but the speed the screen updates
will be reduced.  Move the upper leg by moving the mouse
whilst holding down the left mouse button until the foot
stands on the floor (the orange axis), if you are using the
'Update is Informative' mode, the whole leg will move
(because the lower leg and foot are children of the upper
leg), if you are using the 'Update is Quick' mode, only the
upper leg will move, with the lower leg and foot positions
being updated when you release the mouse button.  Note that
you can move the axes around using the cursor keys so that
you can see the whole leg.

We are now ready to animate the leg.  First we need some
more animation frames.  Press 'f' or select 'set number of
frames' from the animation menu.  Type in 21 as the new
number of frames.  Frames added in this way are always
added to the end of the animation and are exact copies of
the previous last frame.  If you type in a number that is
less than than the current number of frames, the frames
will be deleted from the end of the current animation.

For a simple walk, all we need is four 'key frames', the
rest of the frames can be generated by morphing or
'tweening' between these frames.  We have the first of our
frames already with the leg straight and the foot directly
below us on the floor.  We also need a frame with the leg
stretched out infront, one stretched out behind, and one
directly underneath us, but with the leg bent and the foot
off the floor.

Goto frame 5 by either by pressing 'g' or by selecting
'Goto frame...' from the animation menu, then typing 5 at
the prompt.  This frame can be the 'leg stretched out
behind' frame.  To do this, first change to 'rotate object'
mode by pressing 'r' or selecting 'rotate object' from the
mode menu.  Select the upper leg by clicking the right
mouse button near the middle of it, then with the mouse
over the lower right window, hold down the left mouse
button to rotate the leg to about 30 degrees behind, select
the lower leg and bend it slightly aswell so the leg isn't
quite straight.

Goto frame 10 using the same method as before.  This frame
is going to be the one with the leg directly beneath the
body, but bent.  Select the upper leg, and rotate it
forwards a little, then select the lower leg and rotate it
backwards.  You should notice at this point that the lower
leg no longer rotates along with the upper leg, instead it
stays vertical, this is because the rotation of objects is
only linked if at the time of connection the axes pointed
in the same direction, and the child object has not been
rotated independantly.  Once you have rotated both the
upper and lower leg objects, rotate the foot so the sole
points backwards slightly.

Goto frame 15 using the same method as before.  This will
be the frame with the leg stretched out infont.  Rotate the
upper leg to about 30 degrees infront, then rotate the
lower leg so that it appears straight again.  Finally
rotate the foot so that it is the sole is perpendicular
to the rest of the leg.  We want the foot to be on the
floor in both frames 5 and 15.  Select the upper leg and
change to 'move object' mode (press 'm' or select it from
the mode menu).  Now move the leg down slightly until the
foot touches the floor.  Goto frame 5 and do the same.

All that remains is to create the inbetween frames.  We
have to morph between frames 1 and 5, then frames 5 and 10,
then frames 10 and 15, then frames 15 and 1.  Note however,
that it is not possible to morph between frames 15 and 1,
this is why 21 frames were created instead of 20.  We
simply morph between frames 15 and 21 (which is the same as
frame 1) and then delete frame 21.

Morphing is acheived by pressing 't' (for tween) or by
selecting 'Object Tweening' from the animation menu.  You
will be asked which objects you wish to tween, all of them
(press 'a') or just the selected ones (press 's').  We want
to tween them all, so press 'a'.  Next you will be asked
for the start and end tweening frames.  Type 1 (then press
return) then type 5 (and press return).  You can also set
acceleration and deceleration frames, useful for really
smooth animations, but not required here, enter zero in
both these requests.  The first 5 frames have just been
tweened.  Repeat this process for the other 3 ranges given
above.

Finally, we want to delete the last frame.  Press 'f' or
select 'Set number of Frames' from the  animation menu.
Type in 20 and press return.  As you will be destroying a
frame, you will be asked to confirm your request by
pressing 'y' (or cancel by pressing 'n').  The animation
is complete.  Press 'a' to view the animation.  You have
successfully completed your first animation.  Okay, so it's
not very complex, and it looks a bit silly with only one
leg, but it's a start.

I've covered most of the basic facilities in both editors,
there are others, all of which are fairly obvious or simple
to understand, and all of which are documented in the
on-line help available by pressing the 'help' key.


***********************************************************

Restrictions on object design
=============================

In the Object Editor
--------------------

i) All objects must be convex.
   If you imagine yourself to be standing inside
   the object, you must be able to see all the other
   places inside the object.  A cube, for instance,
   is convex, whereas a horse-shoe is not.

   This restriction arises because each object is
   simply drawn in the order it was defined, so the
   polygon ordering would be incorrect in some cases
   if the object were not convex.  You can, however,
   use this fact to define the polygons in the order
   you wish them to be drawn, an L-shaped object can
   be achieved provided the two 'inner' polygons are
   defined first.

ii)   All polygons must be convex.
   This rule is similar to that above, but there
   is no way round it,  the fact that lines drawn
   up are on the left and down are on the right is
   exploited for speedy polygon rendering, making
   a polygon none-convex will at best make it be drawn
   incorrectly, at worst, make the program crash.
   For this reason there is the aditional restriction
   that polygons must be flat, three sided polygons
   are always flat, but polygons with more sides
   aren't.  None-flat polygons will appear non-convex
   from some directions.

iii)  Polygons must be defined in clockwise order.
   This is a definition rather than a rule, a polygon
   can only be seen from one side, if you're looking
   at the polygon from the front, the points making
   up the polygon must be in clockwise order,
   otherwise you will be able to see the other side
   but not this one.

iv)   Textures.  These must be in 32 colours, you can
   draw them in any 32 of the 16.7 million colours
   available with the AGA chipset, although they
   will only be displayed in the 4096 colours
   available through Amos Professional, and will be
   remapped to the 256 colours available in the game.
   The textures must be saved as 64x64 pixel pictures,
   this is easily done in Brilliance, but in Deluxe
   Paint, you will have to save the picture as brush.
   For other paint packages, play around to see what
   works.  If for some reason the object editor can't
   load the picture, the screen area will appear
   blank.

In the AnimEditor
-----------------

i) You can have no more than 21 objects in any one
   project.  Theoretically, you could have 32, but
   some of the machine code was hard-wired with the
   value 21, and some b****** infected my compter
   with a virus that formatted my hard drive (don't
   worry, the stupid thing killed itself along with
   2 weeks work), and I forgot to back up the machine
   code bits, I could still make it 32 objects, but
   that would involve rewriting the horrible routines
   used in the core of the program, sorry.

***********************************************************

DISCLAIMER
----------
Before anybody starts complaining, this is not a fully
featured rendering package, nor even a partly featured
object designer package, you're getting it FREE with TKG,
it may blow up occasionally, it probably has a few unfixed
bugs, but don't blame me, I won't be held responsible if
you loose a few hours work, because I did and I don't have
anyone to complain to.

***********************************************************

CREDITS
-------

Program design and coding  Charles Blessing
Object Design        Charles Blessing
Alien Design         Micheal Green
Textures       Micheal Green
Music          Ben Chanter
Switch Design        Andrew Clitheroe

***********************************************************

 ================================ ======================
|   __      __  __       __   __ | I wish I could fly,  |
|  /   /_/ /_/ /_/ /  / /_   /_/ | right up to the sky, |
| /_  / / / / / | /_ / /_   /_/  | but I can`t.         |
|                                |   (Orvil & K.Harris) |
 ================================ ======================