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1994-05-20
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THE SPRITE EDITOR
------------------
Written by Scott Lamb
(c) Copyright 1986 Scott Lamb
LOADING THE PROGRAM
The SPRITE EDITOR program may loaded through the workbench, icon
system by double clicking the SPRITE icon, or it may be loaded
from the CLI by typing SPRITE (if the current directory contains
the SPRITE program).
SPRITE creates its own 32 color screen, so that when operating, it
can be pulled down to provide access to a second SPRITE screen or
the WorkBench. The program is designed to be run twice, as two
separate tasks in the Amiga multitasking system, thereby allowing
you to edit two sprite pairs at the same time. While each sprite
pair (FOREGROUND and BACKGROUND) has its own editing screen, the
sprites themselves will be visible from both screens.
THE SPRITE EDITOR
The SPRITE EDITOR lets you edit a double wide sprite image, 32
bits/pixels wide by 21 scan lines high, allowing a total of 672
bits/pixels per image. Why this size? Sixteen bits is two narrow
for most images, so two sprites are combined for the 32 bit
resolution. Twenty-one scan lines corresponds to the height of the
Commodore 64 sprite.This makes conversions from the 64 possible. I
know its arbitrary, since the Amiga sprite can be the full length
of the screen but the line had to be drawn somewhere. If you need
to create sprites larger than 21 scan lines high, use both programs
and position one of the sprites above or below the other (see the
Placement menu). Then you will have to combine the data from the
two separate sprites yourself.
Each sprite half (Left and Right) is stored in a regular data
structure with two words at the start set to x0000, followed by two
words for each of the 21 scan lines that store the image color
values, and two final words set to x0000. Data for the Left half
of the sprite precedes the data for the right half of the sprite.
(see DATA FILES)
When the program first begins (and after the commercial message
requester), you will be asked which sprite priority you want to
edit, either FOREGROUND or BACKGROUND. FOREGROUND edits a double
wide sprite using hardware sprites #2 & #3, while BACKGROUND edits
a double wide sprite using hardware sprites #4 & #5. The FOREGROUND
sprite has priority over the BACKGROUND sprite, so when both are
superimposed on the same screen pixels, the FOREGROUND sprite will
be visible while the BACKGROUND sprite will not be visible.
The FOREGROUND / BACKGROUND requester only appears if both sprites
are available. If SPRITE is already running as a task and has
allocated a sprite, or if another application that is running has
allocated a sprite, then the program will default with the other
available sprite. If no sprites are available, then you will be so
informed.
Besides allowing two different sprites to move past each other,
this allows sprites with 6 colors to be created superimposing the
FORE sprite colors over the BACK sprite colors, when SPRITE is
operating as two tasks on two screens. SPRITE run as FOREGROUND
and SPRITE run as BACKGROUND are each slightly different programs.
They will SAVE the sprites in different files, each being able to
store 100 double wide sprites in each of five separate files.
A SECOND CHANCE
Whenever you choose a potentially hazardous action (Load a file,
Save a file, Quit/Exit, Copy Sprite, etc.) a validation requester
will appear to give you the opportunity to change your mind. This
will reduce the possibility of losing hours of work by accident.
Even still, it is a good idea to save your work frequently.
THE SPRITE EDITOR SCREEN
The sprite editor screen is divided into:
(1) a 672 square EDITING GRID
(2) a 100 sprite numeric IMAGE TABLE
(3) a 4 square sprite COLOR TABLE
(4) a 32 square COLOR CHOICE TABLE
MENU
The PROJECT MENU offers three choice categories:
(1) PROJECT
[a] PICK FILE __ Pick the current sprite image data file from
the following files to be the active file
BACKGROUND FOREGROUND
[1] sprite_1b sprite_1f
[2] sprite_2b sprite_2f
[3] sprite_3b sprite_3f
[4] sprite_4b sprite_4f
[5] sprite_5b sprite_5f
[_#b is back priority]
[_#f if fore priority]
[b] SET DRIVE __ Sets the current device to the following
[1] df0: (Internal floppy disk drive)
[2] df1: (External floppy disk drive)
[3] ram: (RAM disk)
[4] dh0: (Hard disk drive)
[c] LOAD FILE __ Loads the current sprite image data file
into the sprite numeric image table.
[d] SAVE FILE __ Saves the current sprite numeric image
table to the sprite image data file.
[d] QUIT/EXIT __ Quit or Exit the editor.
(2) MODE menu
[a] DISPLAY __ DISPLAY MODE allows you to view the
sprites in the sprite numeric image
table without displaying the sprite
to the editing grid. All Sprite menu
options, except for COPY SPRITE are
deactivated
[b] EDITING __ EDITING MODE allows you to edit the
sprite images in the editing grid,
choose a drawing color, or change a
drawing color. All Sprite menu options,
except COPY SPRITE are activated.
[c] ERASE __ In DISPLAY mode -- erases the sprite
editing grid without erasing the
current sprite.
In EDITING mode -- erases the sprite
editing grid, and the current sprite
image marked by the sprite table.
(3) SPRITE menu
[a] FLIP VERT. _ will vertically invert the image in the
editing grid as well as the current sprite.
[b] FLIP HORZ. _ will horizontally invert the image in the
editing grid as well as the current sprite.
[c] SHIFT RIGHT_ will shift the image one square/pixel
bit to the right in both the editing
grid and the current sprite.
[d] SHIFT LEFT _ will shift the image one square/pixel
bit to the left in both the editing
grid and the current sprite.
[e] SHIFT UP _ will shift the image up one square/scan
line in both the editing grid and the
current sprite.
[f] SHIFT DOWN _ will shift the image down one square/
scan line in both the editing grid and
the current sprite.
[a] COPY SPRITE_ will copy the image within the editing
grid to the current sprite.
(3) PLACEMENT menu
[a] UP __ These three menu options allow you to
[b] CENTER change the vertical position of the
[c] DOWN sprite. This is useful when using
both sprite and sprite-2 together.
USING SPRITE
Choose one of the sprite_n# file names for the current file, and
either begin editing a set of sprites, or load in the sprites
already saved in the file.
MOUSE CONTROL
The sprite editors are all mouse controlled. Pointing the mouse
cursor at a square within one of the grids on the screen, and
clicking the lefthand button will perform the necessary function.
SPRITE TABLE
The sprite table allows you to point to the number of a particular
sprite for either editing or display. When a sprite is chosen
with the mouse, the data stored within that sprite is transferred to
the an active sprite structure and displayed. It is also transferred
to the editing grid if you are in editing mode. A box is drawn
around the chosen sprite to mark it. Sprites numbers are as follows
0 1 2 3 4 5 6 7 8 9
|--|--|--|--|--|--|--|--|--|--|
000__|00|01|02|03|04|05|06|07|08|09|
010__|10|11|12|13|14|15|16|17|18|19|
020__|20|21|22|23|24|25|26|27|28|29|
030__|30|31|32|33|34|35|36|37|38|39|
040__|40|41|42|43|44|45|46|47|48|49|
050__|50|51|52|53|54|55|56|57|58|59|
060__|60|61|62|63|64|65|66|67|68|69|
070__|70|71|72|73|74|75|76|77|78|79|
080__|80|81|82|83|84|85|86|87|88|89|
090__|90|91|92|93|94|95|96|97|98|99|
EDITING A SPRITE
The four boxes beneath the editing grid are the drawing colors that
are available to you. The current drawing color is boxed. The first
box/color is transparent when used in a sprite, so the color is
meaningless to the sprite.
To change the color of the boxed drawing pen, simply point to one of
the 32 colors in the palette grid. That color will be transferred to
the drawing pen. You will note that four of the palette colors are
within a purple rectangle. These are the actual color registers
assigned to the sprite pair. To restore the original color to a
sprite pen, point to the corresponding square within the purple
rectangle.
DRAWING A SPRITE IMAGE
To draw a sprite image first choose EDITING from the Menu. Then
choose a drawing pen (1 of 4). Finally, just point to a square
within the editing grid and hold down the left mouse button. As
long as the left mouse button is depressed and the mouse is moved
slowly, the squares will be flooded with your chosen color, the
corresponding bit in the sprite structure will be illuminated, and
the whole sprite will be copied into a storage array that can be
saved under any of the five file names (FOREGROUND or BACKGROUND)
when you are finished.
COPYING A SPRITE
To copy a sprite from one position in the sprite table to another
position in the sprite table, it is necessary to
(1) Enter EDITING mode
(2) Choose a sprite image from the table,
so that the editing grid portrays the
sprite image
(3) Enter DISPLAY mode
(4) Choose the new sprite into which the
image is to be copied
(5) Select COPY sprite from the menu.
SPRITE DATA STRUCTURE
Sprites are stored in the standard data structure. Each of the
100 sprites in a file require 92 bytes/46 words for a double
sprite image. The first 23 words describe the left half of the
double sprite (hardware sprite #1), while the second 23 words
describe the right half of the double sprite image (hardware
sprite #2). The structure of the sprite image is as follows.
Left Half of sprite
1 pair of words (x0000,x0000) position control bytes
21 pair of words (xnnnn,xnnnn) image data 21 scan lines
1 pair of words (x0000,x0000) next sprite field
Right Half of sprite
1 pair of words (x0000,x0000) position control bytes
21 pair of words (xnnnn,xnnnn) image data 21 scan lines
1 pair of words (x0000,x0000) next sprite field
Position control bytes and next sprite field bytes are set to zero
in the file structure.
SPRITE EDITOR - SPRITE COLOR DESCRIPTOR WORDS
The first word of the data pair is called high order word and the
second word in the data pair is called the low order word. Binary
number pairs created by 1 bit in the high order word with the
corresponding bit in the low order word indicate the color register
number of the bit within the sprite image. The following table
shows the relationship between the binary number pairs, and the
color register numbers.
Binary Hardware sprite pair number sprite
Number 0 & 1 2 & 3 4 & 5 6 & 7 color
00 16 20 24 28 transparent
01 17 21 25 29 pen color 1
10 18 22 26 30 pen color 2
11 19 23 27 31 pen color 3
Sprites 0 & 1 are used for the mouse cursor.
Sprites 2 & 3 are used as the FOREGROUND sprite
Sprites 4 & 5 are used as the BACKGROUND sprite.
Sprite priority (which sprite is seen in front of the other
sprites) is that the lower numbered hardware sprites always have
a higher priority than the higher numbered hardware sprites.
USING SPRITE AS TWO SEPARATE TASKS SIMULTANEOUSLY
If you have at least 512K of RAM in your AMIGA, you can run SPRITE
twice, positioning Sprite Editor screen with FOREGROUND priority
in front of the Sprite Editor screen with BACKGROUND priority. Work
with both editors at the same time. Since each program is on its own
screen it can be scrolled to the bottom of the monitor and out of
the way. The six color sprite that you thus create will be visible
to both programs at the same time.
NOTE
SPRITE will use your standard mouse pointer. As such, it can be
edited in Preferences.
REFERENCES
For a complete description on Amiga hardware sprites, see the Amiga
ROM Kernal Manual Volume 1, and the Amiga Hardware Manual.
IF YOU NEED HELP
If you need help with this program, or if you have any questions
(or if you want to send me $10 for the program,if you think it
worth the price), contact me at
Scott Lamb
205C Heights Lane
Fort Worth, TX 76112
(817) 496-9220
or leave a message through the FIDO net at
TRACK ][ FIDO BBS
(NET 130, NODE 6)
__________________ENJOY!!!!!!____________________
