Overview

| First things first: This document builds on the level customization technology of Zooom, so perhaps it's a good idea to read up on how to build levels before entering this section. Plugins allow you to add custom enemy graphics and behavior to Zooom. A plugin consists of a number of media files and a definition file that tells Zooom how to use the media files. A plugin, once designed, can be declared by a level and after this declaration, all media files defined in the plugin are available to the level. All plugin files must reside in the plugin subdirectory of Zooom. Accordingly, a plugin is distributed as a zip-File, where installation consists of simply unpacking the zip-File into the plugin directory. |

Elements

| The following elements can be part of a plugin and will be accepted by Zooom if placed in the plugin subdirectory and defined in the plugin definition.. |

|  | Background image Zooom displays a scrolling background image as the bottom-most layer of each level. Such background images can be distributet through plugins. Background images must have a width of 400 pixel, as this is the width of the Zooom viewport, and may have any height. They should be in 256 color resolution, not less to make for good visual appearance, not more to save disk space. How to create: Use one of the big graphics packages (Photoshop, Photopaint) or any of a number of shareware graphic applications (ULead) to create textured landscapes, the smoothen the results and apply some FX filters. |
|  | Background music Zooom plays a midi file as a background music during each level. Such midi files can be distributed through a plugin. How to create: Download any of a number of shareware midi editors, or, even better, download one of some hundred thousands of freeware midi files by unknown authors available on the net. |
|  | Enemy fighter graphics The visual appearance of an enemy ship is defined through a frame. A frame is a graphic file in bmp format that contains all animation phases of the enemy ship. Exactly how Zooom interprets the image is defined in the plugin definition file. How to create: Design your ships in a 3D renderer like Lightwave. Render all the frames (no anti-aliasing!). You get individual files. Sample files into one image (manually or with a tiny program I can provide you with). Apply anti-aliasing. Save. |
|  | Definition file The plugin definition file tells Zooom how to interpret the various ressources you are providing within the plugin. How to create: Just use a text editor to write the plugin definition file according to the command set described below. |

Definition

| Following is a definition of all commands that may appear in a plugin definition file. First, some general rules: Plugin definition files must have the extension *.plg. Plugin files should be named according to their theme (eg. "Jungle"), while all related ressources placed in the plugin directory should start with this theme name and an underscore (eg. "Jungle_Background.BMP") to avoid naming conflicts with other plugins. Plugin commands are stated line by line, where lines are seperated with CR/LF, exactly what you get by pressing the ENTER key on your keyboard. It is possible to apply some formatting to plugin commands by pressing TAB several times at the beginning of a line. The according TAB characters will be ignored during interpretation. Some commands have one or more arguments. Arguments must immediately follow a command and have to be seperated by SPACE characters. |
| BEGIN This command must appear before any other statements in a plg file. |
| END This command must appear after the last valid command in a plg file. |
| FRAME bmp_filename framename tilewidth tileheight anidelay This command declares a frame that can be used to define a new enemy fighter. Frames must be declared before they are used in ship definitions. The parameter bmp_filename must refer to an image file residing in the plugin directory, and must be written without the .bmp extension. The parameter framename assigns an internal name to the frame. Under this name, the frame can be accessed when declaring ships. The tilewidth and tileheight parameters tell Zooom how to tile the image file you've provided. Example: An image file with dimensions 360x360 would be tiled into 36 sub-images having dimension 60x60 each if you provide 6x6 for tilewidth and tileheight. The anidelay parameter tells Zooom in what intervall to change from one sub-image to another, if automatic animation is enabled (see ship command for more details). Anidelay is provided in Frames, the basic unit of time measurement in Zooom. The program tries to achieve 100 frames per second, so theoretically, anidelay is measured in 1/100 sec. But on slower machines, the actual framerate may be well below this level, and the animation delay will be down, too. |
| SHIP shipname This command declares a new enemy ship which can be referred in levels by using the parameter shipname. Plugin ships should be named beginning with the name of their plugin theme, followed by an underscore and the name choosen by the developer (eg: JUNGLE_Fighter01). The ship command, in addition to defining a new ship, tells Zooom that all subsequent commands that follow the ship command relate to the ship just defined, until another ship command is issued. |
| FRAME framename Issued after a SHIP command, this command tells the current ship which frame to use as a graphical ressource through the parameter framename, which refers to a frame defined previously in the plugin. |
| ANIMATED Tells the current ship that it should simply cycle through all tiles in its ressource image, and delay between cycles by the time defined in the frame definition through the parameter anidelay. Mutually exclusive with DIRECTED, SHOOTING and TARGETTING within a ship definition. |
| DIRECTED Tells the current ship that it should display tiles from its ressource image according to the ships current direction. The tiles in the image must be ordered from left to right, from top to bottom (simply reading order), by their direction, starting with a tile that shows the ship pointing up, the ship image turning clockwise. The number of tiles you define does not play a role here, Zooom will automatically do all necessary calculations for you. But to achieve persuasive illusion of rotation, you should at least specify 18 frames for the rotation. Mutually exclusive with ANIMATED, SHOOTING and TARGETTING within a ship definition. |
| TARGETTING Tells the current ship that it should display tiles from its ressource image according to the current position of the player ship - the ship seems to always point at the player. The tiles in the image must be ordered from left to right, from top to bottom (simply reading order), by their direction, starting with a tile that shows the ship pointing up, the ship image turning clockwise. The number of tiles you define does not play a role here, Zooom will automatically do all necessary calculations for you. But to achieve persuasive illusion of rotation, you should at least specify 18 frames for the rotation. Mutually exclusive with ANIMATED, DIRECTED and SHOOTING within a ship definition. |
| SHOOTING Tells the current ship that it should display its full animation only when it fires a shot. The number of tiles you define does not play a role here, Zooom will automatically do all necessary calculations for you. As the animation is just played first tile to last tile, the first and last tile should form a seamless transition. Mutually exclusive with ANIMATED, DIRECTED and TARGETTING within a ship definition. |
| HITPOINTS hitpoints Defines how hard it is to kill the current ship, and how much damage the player will take when colliding with the current ship. Hitpoints for the default ships provided with Zooom range from 50 for the small ships, over 250 for the turrets of capital ships, to 3000 for the end game opponent. |
| HITS OFF Tells the current ship that it cannot be harmed by player shots. Usefull for background animations like the bodies of captial ships. |
| SCORE score Defines how many score points will be awarded to the player if he kills the active ship. |
| EXPLOSION explosize Defines how big the explosion of the current ship should be. Values may range from 0 to 4, where 0 suits the smallest ships and 4 is used for endgame opponents. |
| WEAPON weaponnumber Defines which weapon the current ship will use if told to attack in the level definition. The following weapon configurations are defined in Zooom... 0 ... no weapon 1 ... cannon shot, straight down 2 ... cannon shot, in direction of player ship 3 ... cannon shot, in direction of ship 4 ... fireball, straight down 5 ... fireball, in direction of player ship 6 ... fireball, in direction of ship 7 ... laser line, straight down 8 ... fireball, straight down with some deviation 9 ... twin cannon shots, straight down with some deviations 10 ... overkill, used for endgame opponents |
| COMPONENT shipname offsetx offsety This command is used to construct capital ships and other entities composed of more than one ship. COMPONENT tells the current ship that when it is called in a level, it should create subsequent ships of the type defined with parameter shipname automatically. But this components are not created as individual ships; Instead, they inherit all relevant information like position changes or attack mode from their "parent", namely the ship declaring the component. To allow for the components to be placed anywhere on their parent, parameters offsetx and offsety provide the offset position as compared to the center of the parent ship at which the component should be placed. Note: If the parent of a component is not declared with the option HITS OFF, and a component is placed inside the parent using the offset parameters, the player will not be able to kill the components, as all shots will hit the outlying ship and explode. This can, of course, be deliberately used to create hard opponents, but when creating capital ships, your intention is to provide turrets that *can* be killed, so declare the parents as HITS OFF in this case. By the way, if the parent is killed, all its components will of course be killed instantly and automatically. |

Examples

| BEGIN FRAME jungle_ship00 jungle_ship00 6 6 1 FRAME jungle_ship01 jungle_ship01 4 3 1 FRAME jungle_ship06 jungle_ship06 1 1 1 SHIP jungle_fighter FRAME jungle_ship01 HITPOINTS 50 ANIMATED WEAPON 0 SCORE 1000 EXPLOSION 1 SHIP jungle_turret FRAME jungle_ship00 HITPOINTS 175 TARGETTING WEAPON 2 SCORE 5000 EXPLOSION 2 SHIP jungle_destroyer FRAME jungle_ship05 HITPOINTS 100 HITS OFF COLLISSIONS OFF WEAPON 0 SCORE 0 COMPONENT jungleturret -25 -11 END |