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The forms in Fig. 9-4 through 9-7 can be used
assign names to all of the different areas of your
as design aids when you are creating sprites. There
graphics. The assembler can be directed to store the
are four different sizes available. The different sizes
graphics data anywhere in memory. The main disad-
correspond to the sprite X and Y multiplier options.
vantage of entering the data into the assembler is
x
If you decide to use one of the e panded
sprites, that the data will be reassembled each time a
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change is made in your program. Depending on the use of one graphics mode over another. If your ap-
amount of graphics data that you have, this can a 1 plication requires the use of a certain graphics mode,
substantially to the time that it will take to assem- the graphics package that you choose must use the
ble the file. Another option would be to assemble
the graphics data separately from the main pro-
gram. If you do this, you must give the main pro-
gram the addresses of where the graphics data will
be located. In this case, the graphics data need be
assembled only once. (Or, at least only as often as
is needed to get the data correct.)
USING A GRAPHICS TABLET
A more popular way in which to enter graphics
data into the Commodore 64 for use within the pro-
gram is to use commercially available graphics
packages to generate pictures. One of the most
popular and useful of these is the Koala Pad. This
package comes with a touch pad and software that
allows you to easily generate background screens.
Almost any type of graphics package will help speed
up the process of generating graphics.
A word of caution: before selecting a graphics
package to aid with your drawings, it would be wise
to be sure that it will fullfill your needs. There are
two major pieces of information that you will need
about the package:
" What graphics mode does it use?
" How can the picture be retrieved for m the disk?
Different types of games will benefit from the
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same mode. Otherwise, the data created will not be
you can get no satisfactory information from the
useful for your program. This sounds like good ad-
manufacturer, or they claim that you have no right
vice in theory; however, you will probably find that
to know, you should not buy their software package.
most of the available packages will use the
When shopping for a graphics package, one
multicolor bitmapped mode. On the other hand,
especially useful feature is a zoom mode. Using a
even if the program can not be used to generate
zoom mode, you will normally be able to change in-
data, it may be useful for testing color choices and
dividual pixels on the screen with a minimum of ef-
to see how things will look.
fort. This will allow you, among other things, to
It is quite possible that you will find a graphics
clean up a drawing that was made free-hand or
package that will seem to do everything that you
create a shape pixel-by-pixel, which is too intricate
would like it to, only to find later on that you can't
to create in any other way.
get your picture back off the disk. It wouldn't seem
Be wary of a piece of software that will not
to be very useful to create a picture if you can't use
allow you to use all 16 of the colors that the Com-
it. Some graphics packages use what appear to be
modore 64 can display or does not use the full
protected file names to prevent you from retrieving
resolution of the screen. After all, there is no reason
your picture without using the software that created
to sacrifice any of the abilities of your machine
it. You should contact the manufacturer of the
because of some other programmer's shortcomings.
graphics package if there is no documentation on
In fact, most good graphics programs will give you
how to load the picture wit out their software. If
a pallette of more than 16 colors by giving you mix-
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tures of the different colors in different patterns. an inverted spade and is inaccessible from the
This can give you a choice of many colors and keyboard. Koala uses this character as a flag to iden-
shades of colors that you may not have been aware tify files that it has saved on the disk. This character
were possible. is followed by the character string PIC, which is
Another feature that you will learn to appreciate followed by a picture letter and a space.
greatly is an OOPS command. This usually allows A pair of utility programs that will convert file
you to erase the last changes that you have made names to and from the Koala Pad format are in Ap-
to your drawing. This is a very useful function when pendix C. These are:
you wish to experiment with color changes and
other types of changes or additions that you might Listing C-12 KO-COM Changes the name from
not be sure you like. If you don't like your change,
Koala format to
you simply give the OOPS command and your draw-
Commodore format.
ing is returned to the state it was in before the
Listing C-13 COM-KO Changes the name from
change.
Commodore format to
The following section will give some informa-
Koala format.
tion about the Koala Pad from Koala Technologies.
Some of the information has come from the
These are BASIC programs that will prompt
manufacturer and is not in the documentation that
you for the current filename and the name that you
comes with the package. This is not by any means
would like the file to be called. When using COM-
the only software package that will aid in game
KO, the program will insert the special character
design; it is only being used as an example. A
at the beginning of the name for you.
number of manufacturers have recently released
After you have changed the name of the file in-
light pens with graphics software, which may be
to something that can be loaded, you will be able
useful. There are also digitizing tablets, joystick
to use your machine language monitor to examine
controlled graphics software, and keyboard con-
and reconfigure the data. The data is stored on disk
trolled graphics software, which might be suitable.
in the following format:
To attempt to evaluate all of the different packages
is beyond the scope of this book. The preceding in-
Koala Memory Map
formation should aid in your evaluation of a product
in the stores, and the following information on the
$6000 - $7F3F
Graphics image
Koala Pad should show you what type of informa- $7F40 - $8327
Color memory image
tion you will need to properly use the package of
$8328 - $87OF
Color RAM image
your choice. $8710
Background color
Using a Koala Pad
Note: If you are using a cartridge based machine
The Koala Pad is a touch sensitive tablet with language monitor, you may not be able to read the
an active area of 4" by 4" and a resolution of 256 file as the cartridge replaces the RAM where the
by 256 points. The pad plugs into one of the joystick data will be loaded.
ports on the Commodore 64 and is treated as a pair After you have loaded the file, you can relocate
of game paddles by the software. the graphics data and the color data to anywhere
File format. Before you try to use the data that is convenient to your program. You should then
created on the Koala Pad, you will want to convert save your newly created file back to the disk. You
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