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--PRESS ESCAPE TO EXIT-- -------------------------------
MAP-STATION V1.02 DOCUMENTATION
-------------------------------
-------------------
-- Starting note --
-------------------
This is the complete documentation for the program. A simple on-line
help is available within the program by pressing [HELP] on the keyboard.
This help is available at all times except when a file requester or the
icon bar is displayed.
-----------------------------
-- Purpose of this program --
-----------------------------
This program is a game level-map editor which I have produced to aid me
in designing the levels for a game I am currently in the process of
developing in assembly language.
The way a level is made up is out of a collection of graphical
blocks which can vary in size (usually 16x16 or 32x32 pixels). When the
blocks are originally created within a paint program they are drawn so that
they will fit together to make larger objects. If done properly a level of
a game can take up considerably less memory than having the level made out of
one big picture (which if the level was of a reasonable size would be
larger than available memory as a single 320*256 32 colour screen eats up
over 50k alone) and can look just as good.
Without a map editor it can be a real chore designing a level in any
programming language because the block numbers have to be typed in by hand as
data statements (BASIC), dc statements (ASSEMBLY) etc. This can be a
laborious process especially if the level is quite big and also you don`t
instantly know what the level is going to look like.
A map editor allows you to select a block from the amount available and
using the mouse paste it onto the level map at any position. This way you
can see straight away what the level is going to look like when it is in
the actual game and any mistakes can be corrected or changes can easily be
made. As more blocks are drawn they can easily be added to the list available
for use within the level.
--------------------------
-- Usage of the program --
--------------------------
This editor can be controlled using a combination of icons and keyboard
presses. Some functions are available using both while others are only
available using one or the other. The map editor has five separate modes
which have their own screen and some functions are only selectable when on
the particular screen related to the function. The five modes are:
Block cut - Used for cutting blocks from an IFF picture
Block select - Used for selecting which block to paste onto the map
Block edit - Used for editing existing blocks and making new blocks
Map edit - Used for pasting blocks onto the map and removing blocks
Cut-Buffer mode - Used for grabbing chunks of the map or for creating
chunks to paste onto the map
The menu is activated by moving the mouse to the top of the screen and
pressing the right mouse button. The menu bar will then glide to the top
of the screen and an option can be selected or you can remove the menu (by
pressing the right mouse button again - with the mouse at the top of the
screen). At this point the menu will then glide off the bottom of the
screen.
The menu options are:
Row one
-------
1. Load IFF - Loads an iff picture for cutting blocks from (only in Block
cut mode).
2. Load Level - Loads a complete level into level bank (Palette, Blocks,
Map).
3. Save Level - Saves complete level from level bank (Palette, Blocks,
Map).
4. Load Blocks - Loads new blocks into bank.
5. Save Blocks - Saves current blocks from bank.
6. Load Map - Loads new map into bank.
7. Save Map - Saves current map from bank.
8. Clear Blocks - Clears blocks from bank.
9. Clear Map - Clears map from bank.
10. Exit program - Does just that.
Row two
-------
1. Block Cut - Enter Block-Cut mode.
2. Block Select - Enter Block-Select mode.
3. No option.
4. Block Editor - Enters Block-Edit mode.
5. No option.
6. No option.
7. No option.
8. No option.
9. Map Editor - Enters Map-Edit mode.
10. No option.
Row three
---------
1. Store Block - Stores selected block from block-cut screen.
2. Merge Blocks - Merges two blocks (One over the other).
3. Set no. of Blocks - Set number of blocks available.
4. Block X-Flip - Flips edit block horizontally.
5. Block Y-Flip - Flips edit block vertically.
6. Block Insert - Inserts edit block into bank.
7. Block Replace - Replaces block in bank with edit block.
8. Erase Block - Clears block from block edit screen.
9. Set Map Dimensions - Set new height and width of map (Block-Edit mode).
10. No option.
Available in all modes
----------------------
Load entire level - Select the "Load Level" icon (Row 1, Column 2) to load
Palette data, Map data and Block data together.
Save entire level - Select the "Save Level" icon (Row 1, Column 3) to save
Palette data, Map data and Block data together.
Block cut mode
--------------
Load IFF - Select the "Load IFF" icon (Row 1, Column 1) to load an IFF
picture from which to cut blocks from.
Cut Block - The block to be cut out is outlined using a 16x16 box which is
moved around with the mouse. The left mouse button is then pressed to lock the
box onto the block. To grab the block either call up the menu and click the
"Store" icon (Row 3, Column 1) or press the [G]rab key. The display will then
momentarily flip to the Block select screen where you store the block by
clicking with the left mouse button on the place you want it to go. After
this has been done you will return to the Block cut screen. To release the
box again press the right mouse button.
Block select mode
-----------------
Load Blocks - Select the "Load Blocks" icon (Row 1, Column 4) and then
select the name of the block screen to load using a file
requester.
Save Blocks - Select the "Save Blocks" icon (Row 1, Column 5) and select
the name of the block screen to save using a file requester.
Delete Blocks - Select the "Delete Blocks" icon (Row 1, Column 8).
Merge 2 blocks - Select the Merge Blocks" icon (Row 3, Column 2) and click
the left mouse button on the block to use as the background
and the right mouse button on the block to use as the
foreground the click the left mouse button on the place to
store the block.
N.B Any pixels with are set to the background colour
(colour 0) on the foreground block will show through
the background block.
Select block for map - Click the left mouse button on a block.
Select block for edit - Click the right mouse button on a block.
Grab block from edit screen - Press F9
Scroll blocks up or down - Cursor Up/Down
Change no. of blocks available - Select the "No. Blocks" icon (Row 3,Column 3)
You are then able to change the number of
blocks available on the info bar at the
top of the screen. The value you enter
will be scaled to the nearest 20. If you
the value you enter will be changed to 320
if it is less than this as 320 is the
minimum number of blocks allowed.
Block edit mode
---------------
Plot a pixel - Position the mouse pointer on the place you require in the
expanded box and click the left mouse button.
Clear a pixel - Position the mouse pointer on the place you require in the
expanded box and click the right mouse button.
Area fill - Position the mouse pointer on the area to fill and press
[Space].
Change map dimensions - Select the "Map Dimensions" icon (Row 3, Column 9)
then type in the map width and press and then the map
height and press [Return]. The current map will then
be cleared and the new map size will be set.
N.B. If the size you specify for the map exceeds
the amount of available level bank memory
then you will need to re-enter the map
dimensions.
The minimum map dimensions are 20x16. If the
values entered are any less than this they
are replaced with these values instead.
Flip block horizontally - Select "Flip-X" icon (Row 3, Column 4) or press
[X] on the keyboard.
Flip block vertically - Select "Flip-Y" icon (Row 3, Column 5) or press [Y]
on the keyboard.
Insert block - Select the "Insert Block" icon (Row 3, Column 6). The Block
select screen will be displayed where you click the left mouse
button on the position to insert the block after which you return
to the Block edit screen.
Replace block - Select the "Replace Block" icon (Row 3, Column 7). The block in
the edit window will then replace the original.
Clear block - Select the "Clear Block" icon (Row 3, Column 8). The edit window
will then be cleared. This function doesn't affect the actual
block data - to actually clear the block perform a replace after
this function (See previous function).
Generate mask for block - Press the "G" key. This will generate a collision
mask for the block which will then be displayed in the right-
hand window. This can be edited in the same way as the block
data except that left-mouse=colour 1 and right-mouse=colour 0.
Change current ink colour - This decides which colour to fill or plot a
pixel with. To change the colour click the
left mouse button on one of the 32 different colour
boxes at the bottom of the screen. To show
which colour is currently selected there is
a bar going across the top of the colour boxes.
Change a colour in the palette - Select a colour to change and then alter
the Red, Green and Blue values adjusting the 3
slider bars on the screen until the desired
colour is obtained.
Draw a line - Press the "L" key to initiate, then hold down the left mouse
button to set the first point and whilst keeping the button
held down move the mouse to the desired position for the
second point and release the mouse button. To cancel the line
press the right mouse button while positioning the second
point and the screen will be restored. After the line has been
drawn you are returned to pixel mode.
Map edit mode
-------------
Load a new map - Select the "Load Map" icon (Row 1, Column 6) and then
select the name of the map to load using the file
requester. The map will be loaded and the size of the map
will be taken from the 8 byte header.
Save current map - Select the "Save Map" icon (Row 1, Column 7) and then
select the name of the map to save using the file
requester. The map will be saved along with an 8 byte
header which contains the height and width of the map.
Clear current map - Select the "Clear Map" icon (Row 1, Column 9) and the
map will then be erased from the screen and memory.
The map will also be cleared if you change its size
(See above).
Paste a block - Move the mouse pointer to the desired position and press
the left button.
Clear a block - Move the mouse pointer to the desired position and press
the right button.
Pick up a block to use from the map - Move the mouse pointer to the desired
block and then press the space bar.
The block under the mouse will then
become the current block.
Scroll map right - If the size of the map allows it and you are not at the
right-most position press the right cursor key and the
map will scroll 1 block right.
Scroll map left - If the size of the map allows it and you are not at the
left-most position press the left cursor key and the
map will scroll 1 block left.
Scroll map down - If the size of the map allows it and you are not at the
down-most position press the down cursor key and the
map will scroll 1 block down.
Scroll map up - If the size of the map allows it and you are not at the
up-most position press the up cursor key and the
map will scroll 1 block up.
Set status bits at map pos - Move mouse to required block on map and press
(See later section) keys [1] - [7] on main keyboard. That block
will then be outlined and the status bit will
be set. Only those bits which are available
can be set and this depends on the no. of
blocks set up.
Clear all status bits from map pos - Move mouse to required position and press
(See later section) [DEL] on the keyboard. All outlines and
status bits will be cleared.
See status bits set on block - Move mouse to required block. The state
(See later section) (0/1) of the available bits will be shown
on the bar at the top of the screen (next to
screen x and y positions).
---- If chunk has been grabbed ----
(If chunk is grabbed the size of the chunk is indicated by a different
mouse pointer showing top and bottom corner positions and the mouse buttons
react differently)
Paste chunk to map - Press left mouse button at required position.
Clear area the size of chunk - Press right mouse button at required
position.
Cancel chunk paste mode - Press both mouse buttons together.
Cut-Buffer mode
---------------
Enter cut-buffer mode - Press the "B" key.
Create a chunk to paste onto map - Select blocks from the block screen and
paste them down onto the cut-buffer
screen with the left mouse button
(Right mouse - Clear block,Space - Grab
block from cut-buffer screen).
Grab chunk from cut-buffer screen - Press the "Return" key (Main keyboard)
to initiate function. Press left mouse
button on top left corner, keep button
down and move mouse to bottom right
corner then release button.
Grab chunk from map screen - Press the "Enter" key (Keypad) to initiate
function. Grab chunk in the same way as if
from cut-buffer screen.
---------------------------
-- Technical information --
---------------------------
Assembly language fundamentals required to use level data properly
==================================================================
In Basic and most other high-level languages memory is treated in
the form of variables and arrays which is all the user needs to be
concerned about to do anything. In machine code however memory is treated in the
form of memory addresses which can be accessed in three different ways
depending on the maximum value required to be stored. These sizes are
called bytes, words and longwords. A byte is a single element in memory in
which a single AscII character eg. "D" can be stored (1k = 1024 bytes, 1
meg = 1024k = 1048576 bytes). A byte can store a number between the range
of 0-255. As you can imagine this is not enough for most purposes so other
sizes are available (Words and Longwords). A word is two bytes and can
store a value between 0-65535. A longword is two words (four bytes) and can
store a value between 0-4294967295.
The map data in case you weren't sure doesn't actually contain the
graphic data for every block but instead contains a number which relates to
the corresponding block in the graphics set. I was originally storing each
block number in a byte but this restricted the amount of blocks that could
be used to a maximum of 255 so instead I decided to store each number in a
word (Max. value of 65535). This was more than enough (A longword would
have been over-extravagant and uneccessary).
I will now explain another fundamental concerning memory systems.
Decimal is called base 10 (Because there are ten values in the numbering system
- 0-9). Computers don't work with decimal but instead use two other numbering
systems called Binary and Hexa-Decimal. Binary is called Base 2 and values can
be either 0 or 1. Hexa-Decimal is called Base 16 and there is a maximum of
sixteen values (To make up the extra 6 values the first 6 letters of the alphabet
are used - A-F i.e 0123456789ABCDEF).
Binary makes use of another method of accessing memory. It accesses
memory on individual bits. A bit can either be set (1) or clear (0). A byte
contains 8 bits, a word contains 16 bits and a longword contains 32 bits.
So as to make this easier to understand I will explain how to convert
between decimal, binary and hexa-decimal. This may sound unusual but bits
are referenced from the far right of the address working towards the left.
The highest bit (Bit to extreme left) is called the Most Significant Bit (MSB)
and the lowest bit (Bit to extreme right) is called the Least Significant
Bit (LSB).
Values for bits in a byte (8 bits)
-------------------------------------------------
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| -----------------------------------------------
| Value | 128| 64 | 32 | 16 | 8 | 4 | 2 | 1 |
-------------------------------------------------
If you add up the value of all the bits (0-7) you will see that the total
is 255 which is the maximum value which can be stored in a byte.
From the table you may have gathered that the way to convert from decimal
to binary is to find out which bits added together make up the number.
The easiest way of doing this is to get from the table the value of the
highest bit which is less than the decimal number eg. If we wished to
convert 100 to binary we would see that the nearest value we could start
with was 64 (128 is too high). We then subtract 64 from the number which
leaves us with 36. We then repeat the process and get the bit with the
value of 32. We subtract 32 from 36 and are left with 4. We see there is a
bit which is this value. This means that we have converted the number to
binary. The bits we need to set are bits 6,5 and 2. Even though the bits
are accessed from the right to the left when a binary value is typed into
the computer it is entered from bit 7-0 (Left to right). Therefore the
binary value for 100 (Decimal) is 01100100. Here are a few more examples
just to get you more used to this.
Decimal 92
64+16=80
80+8=88
88+4=92
Bits to use are 6,4,3 and 2
Binary 92 = 01011100
Decimal 15
8+4 = 12
12+2 = 14
14+1 = 15
Bits to use are 3,2,1 and 0
Binary 15 = 00001111
I hope this hasn't confused you too much. If it has don't worry
about it. When I first started writing in machine code I found it
confusing but once I had used it for a while it became second nature
to me.
Values for bits in a word (16 bits)
Bit 0 = 1
Bit 1 = 2
Bit 2 = 4
Bit 3 = 8
Bit 4 = 16
Bit 5 = 32
Bit 6 = 64
Bit 7 = 128
Bit 8 = 256
Bit 9 = 512
Bit 10 = 1024
Bit 11 = 2048
Bit 12 = 4096
Bit 13 = 8192
Bit 14 = 16384
Bit 15 = 32768
As you will probably have noticed the value for each bit is twice
the value of the previous bit. Therefore it's easy to work out the extra
bits required for a longword (16-31) by doing this.
I will now move on to explain how hexa-decimal fits into this. I
may as well start off by telling you that it is much easier to convert a
number from decimal to binary and then from binary to hexa-decimal than
it is to convert a number straight from decimal to hexa-decimal.
As previously mentioned hexa-decimal has 16 possible digits (0-F).
A hexidecimal digit takes up four binary bits (Called a nibble - Half a
byte). Therefore a byte can store 2 nibbles, a word can store 4 nibbles
and a longword can store 8 nibbles. In case you haven't already guessed
this is how you do the conversion.
Decimal number 78 = Binary 01001110
This binary number is then split up into two nibbles
0100 and 1110
These nibbles contain 4 bits (0-3) and the values for each bit are
taken as follows
Bit 0 = 1
Bit 1 = 2
Bit 2 = 4
Bit 3 = 8
Therefore to work out the hexa-decimal value we place the bits
below the decimal values as so
Nibble 1 Nibble 2
8 4 2 1 8 4 2 1
0 1 0 0 1 1 1 0
The value of the first nibble is 4 and the value for the second is
7. This means that Decimal 78 = Hexa-Decimal 47.
In this case we required only two nibbles (two hex digits) because
the number fitted inside a byte. If the decimal number was higher than
255 and lower than 65536 it would have been stored in a word (4 nibbles)
and if the value was 65536 or greater it would have been stored in a
Longword (8 nibbles).
I hope this section has been understandable. If not keep going through
it and hopefully you will pick it up and start to find it easy.
Memory layout of the level bank
===============================
If you don't know any of the fundamentals of assembly language programming
I strongly recommend that you read the previous section to understand fully
the following information.
--- Level Header Chunk ---
Longword - "LEV"
Longword - Size of chunk (Bytes)
Longword - Size of whole level (Bytes)
Longword - Offset of colour palette chunk from start of bank
Longword - Offset of map data chunk from start of bank
Longword - Offset of block data chunk from start of bank
Word - World No.
Word - Level No.
20 Bytes - AscII string for world name
20 Bytes - AscII string for level name
--- Palette Data Chunk ---
Longword - "PAL"
Longword - Size of chunk (Bytes)
Word - No. of bitplanes for level
Word - Palette type (0 - Normal, 1 - AGA (Not supported))
Longword - Offset for copper structure
? Words - Colour palette data
-- Copper Structure (Not currently implemented but space is reserved)
Word - Copper type (0 - Normal, 1 - AGA (Not supported))
Word - Colour number to use for copper (0-255)
Map-Height*16 words - line colour
--- Map data chunk ---
Longword - "MAP"
Longword - Size of chunk (Bytes)
Longword - Map width (Blocks)
Longword - Map height (Blocks)
? Bytes - Map data ((Map-Width*2)*Map-Height) ¹
--- Block data chunk ---
Longword - "BGFX"
Longword - Size of chunk (Bytes)
Word - No. of blocks (Maximum)
Longword - Offset for mask data (Collision masks for blocks)
? Bytes - Block data (Gfx) ²
? Bytes - Block data (Masks) ³
¹ Each block in the map is stored as a number of word size
² Block data is stored in a special format called raw-blit/interleaved
format. Each block is 16 pixels x 16 pixels and stored in the following
way:
Word 1 - Line 1 (Bitplane 0)
Word 2 - Line 1 (Bitplane 1)
Word 3 - Line 1 (Bitplane 2)
Word 4 - Line 1 (Bitplane 3)
Word 5 - Line 1 (Bitplane 4)
Word 6 - Line 2 (Bitplane 0)
Word 7 - Line 2 (Bitplane 1)
Word 8 - Line 2 (Bitplane 2)
.... etc ....
This format is the best way to store graphics for use with the Amigas
blitter chip as it allows the blitter to draw the block quicker. All
blocks are stored in sequential order (Block 0,1,2,3,4 etc).
³ A mask is combination of all the bitplanes of a block and therefore
contains all the pixels set in a block. There is space for a mask for
each block in the set but actual data will only be stored here if you
have specifically generated a mask for a block in the block editor and
then stored the block again using either the insert or replace functions.
The purpose of a mask is so that you can see which areas of a block are
detected as a collision. If you don't know how to detect collisions in
this way then this feature won't be of much use to you.
Further explanation of status bits
==================================
As previously stated I decided to use a word to store each block number in the
map. If you are with me you will see that a word has 65536 values (0-65535) and
16 bits (0-15). Therefore the number of blocks available for use with the map
are 65536. I decided that I was unlikely to use that many blocks and so what
I did was to allow for the 7 high bits of the word to be used for status
bits (Bits 15-9). Therefore I implemented a function which produced the
following actions:
Key-Press Bit set
1 15
2 14
3 13
4 12
5 11
6 10
7 9
If all 7 of these bits were to be used as status bits that would mean
that the max number of blocks available would be 512 (0-511). Here is a
table so you can work out how many blocks will be available depending on
the number of status bits you will be using:
Max number of blocks No. of status bits
512 7
1024 6
2048 5
4096 4
8192 3
16384 2
32768 1
65536 0
The status bits are then masked out (Cleared) to get the correct block
number from the word. Individual functions in the game can then be assigned
to the bits which are free. This way you can make each of the bits perform
a different kind of function depending on the players position in the level
eg. Bit 15 could be used to tell your routines that this block cannot be
walked through because there is a collision zone on that block etc. In the
documentation I was providing some example uses for the bits and by no
means do you have to abide by these. It depends totally on how you make use
of the bits within your routines.
Therefore to find out if any status bits are set on a map position.
Retrieve the relevant word from the map data into a variable (To see how to do
this you will need to refer to the Source-Code) and then mask out (Clear) the
bits which relate to the block number in the variable and then use the
bit-test instruction (Explained in the Amos manual) to see whether certain
status bits are set or not.
If you wish to ignore the status bits and just display the block then clear
all the status bits.
If you are still unsure about the use or purpose of this function then
please don't hesitate to phone me on (0722) 326057 or write to me. At
the end of the day though, this is just a minor function within the map
editor intended to make life easier. It isn't essential to understand what
it is for.
-----------------------
-- Other information --
-----------------------
You can contact the following address if you want to know more about the
program or if you wish to speak to me about anything related to AMOS or
assembly language (I will try to help you with problems you may have) or
suggest anything to include in updates.
The address is:
11 MACKLIN ROAD
SALISBURY
WILTSHIRE
SP2 7HB
ENGLAND
TEL. (0722) 326057
----------------
-- Final note --
----------------
I hope that you enjoy using this program and that it proves to be
beneficial to you. - Clive Minnican (Programmer).
This program is copyright (c) 1993.
-------------XXXXXXXX-------------
