17 Bit Software 4: Phase Four

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Text File | 1992-09-02 | 27.4 KB | 700 lines

--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-------------