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<!DOCTYPE html>
<html>

<head>
<meta charset="utf-8">
<title> Trackballs - API Reference </title>
<link title="Default style" rel="stylesheet" href="default.css" type="text/css">
</head>

<body>

<div class="toc">
<ol>
<li> <a href="index.html"> Players guide </a> </li>
<li> <a href="customizing.html"> Creating your own levels </a> </li>
<li> <a href="mapeditor.html"> Map editor </a> </li>
<li> <a href="scriptingLanguage.html"> Scripting Language </a> </li>
<li> <a href="api.html"> API Reference </a> </li>
<li> <a href="examples.html"> Examples </a> </li>
</ol>
</div>

<div class="pagebody">

<h1> API Reference </h1> This page serves to document all the API functions that are available for level designers of trackballs. Since it is currently under construction it is not complete and you can find some more inforamtion about the functions in existing levels or by looking in the <tt>guile.cc</tt> file in the source code.

<h2> Creating animated objects </h2> These objects are any drawable and movable object in the world and a number of API functions can 
be used to create them. See the section below for functions to modify their properties. <b>Note:</b> all objects can be placed at 
any real coordinate; an object placed at (15.0,15.0) will be in the center of the map cell (15,15). 
<p/>

<div class="fn">
<div class="fn-proto">(player)</div>
<div class="fn-text">
Returns the current player as an 'animated' object. When there is no player, (i.e, when editing the map) returns unspecified.
</div>
</div>

<div class="fn">
<div class="fn-proto">(new-mr-black x y)</div>
<div class="fn-text">
Creates an opponend ball at specified position. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(new-baby x y)</div>
<div class="fn-text">
Creates a baby ball at specified position. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-teleport x y dx dy radius)</div>
<div class="fn-text">
Creates a teleporter at specified position with specified destination dx/dy expressed as absolute coordinates. Radius is the size of the teleporter. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-bird x y dx dy size speed)</div>
<div class="fn-text">
Creates a bird at specified x/y position, with specified destination dx/dy. Size and speed indicates the size of the bird and it's movement speed. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-flag x y points visible radius)</div>
<div class="fn-text">
Creates a flag giving points when captured. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-colormodifier col x y min max freq phase)</div>
<div class="fn-text">
Allow to modify the color(s) of a cell. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-heightmodifier corner x y min max freq phase n1 n2 n3)</div>
<div class="fn-text">
Allow to modify the height of a cell's corner. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-cactus x y radius)</div>
<div class="fn-text">
Creates a cactus at given position with given radius. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-spike x y speed phase)</div>
<div class="fn-text">
Creates a lethal spike going up and down. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-sidespike x y speed phase side)</div>
<div class="fn-text">
Creates a lethal spike (comming from the side). Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-goal x y rotate-p next-level)</div>
<div class="fn-text">
Adds a new goal to the map. Orientation is given by rotate-p (horizontal or vertical) and the next level to go to is given as a string name (eg. "foo" to go to level "foo.map"). Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(sign text scale rotation duration x y [z])</div>
<div class="fn-text">
Creates a new sign with the given text/scale/rotatation. Duration determines how long it lasts, if duration
<0 then it lasts forever. The last 'z' argument is optional. Returns an 'animated' object </div>
</div>

<div class="fn">
<div class="fn-proto">(add-modpill x y kind length resurrecting)</div>
<div class="fn-text">
Adds a new modpill at x,y with given kind. Kind must be one of the '*mod-' varibles, see below, and determines the effect of the pill. Length determines how long it's effect lasts and resurrecting how long until the modpill reappears on the map after it has been taken. Use resurrecting = 0 if the pill can only be used once. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(forcefield x y z dx dy dz height allow)</div>
<div class="fn-text">
Returns a forcefield extending from x,y,z to dx,dy,dz. The 'z' arguments are given relative to the ground position. Height gives the height of the forcefield and allow is the sum of one of *ff-nothing*, *ff-kill1*, *ff-bounce1* and *ff-nothing*, *ff-kill2*, *ff-bounce2*. This determines if nothing happens, if the player is killed or bounces depending on in which direction he tries to pass the force field. The flags *ff-kill* and *ff-bounce* are shortcuts for (+ *ff-kill1* *ff-kill2*) and (+ *ff-kill1* *ff-kill2*) respectively.
<p/> Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(switch x y on off)</div>
<div class="fn-text">
Creates a switch at x/y with the two function 'on' and 'off' which are called when the player toggles the switch to be on or off. Returns an 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(pipe x0 y0 z0 x1 y1 z1 radius)</div>
<div class="fn-text">
Creates a pipe going from x0/y0/z0 to x1/y1/z1 with the given radius. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(pipe-connector x0 y0 z0 radius)</div>
<div class="fn-text">
Creates a new pipe connector. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(diamond x y [z])</div>
<div class="fn-text">
Creates a new diamond 'save point'. Returns an 'animated' object
</div>
</div>

<div class="fn">
<div class="fn-proto">(fountain x y z rand-speed radius strength)</div>
<div class="fn-text">
Creates a new fountain object. Returns an 'animated' object
</div>
</div>

<h2> Operations on animated objects </h2> These functions can be applied to most animated objects returned by the functions above in order to change their appearance, properties or even trigger callbacks on specific events.

<div class="fn">
<div class="fn-proto">(set-position obj x y [z])</div>
<div class="fn-text">
Sets the position of specified 'animated' object. Accepts optional z-coordinate.
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-position-x obj)</div>
<div class="fn-text">
Gets the X position of the specified 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-position-y obj)</div>
<div class="fn-text">
Gets the Y position of the specified 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-position-z obj)</div>
<div class="fn-text">
Gets the Z position of the specified 'animated' object.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-modtime obj mod time)</div>
<div class="fn-text">
Alters time left for object (must be a ball or a pill) to have the given modification. 'mod' is here one of the '*mod-' predefined variables, see below.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-acceleration obj accel)</div>
<div class="fn-text">
Sets acceleration of given computer controlled ball object (mr black or baby) to make it easer/harder for the player.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-horizon obj horizon)</div>
<div class="fn-text">
Sets AI horizon of given computer controlled ball object (mr black or baby). The ball will not chase the player if he is beyond this distance.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-primary-color obj red green blue alpha)</div>
<div class="fn-text">
Sets the primary colour of the object from the given colour values. Values must be in the range 0.0 to 1.0. The actual drawing effect depends on what type of object is beeing drawn but most objects use this colour in their display.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-secondary-color obj red green blue alpha)</div>
<div class="fn-text">
Sets the secondary colour of the object from the given colour values. Values must be in the range 0.0 to 1.0. The actual drawing effect depends on what type of object is beeing drawn. Not all objects use this colour in their display.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-specular-color obj red green blue alpha)</div>
<div class="fn-text">
Sets the specular (aka. "highlight") colour of the object from the given colour values. Values must be in the range 0.0 to 1.0. The actual drawing effect depends on what type of object is beeing drawn. Not all objects use this colour in their display.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-flag obj flag state)</div>
<div class="fn-text">
If state is true, then the given flag will be turned on for the object. Otherwise it will be turned off. The available flags and the results of the flags are dependent on the actual object used.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-wind pipe forward backward)</div>
<div class="fn-text">
Sets the forward/backward wind of a pipe object. Can be used to force the player to travel in one specific direction (or ease travells in both) when entering a pipe. If forward is positive then it will be easier to travell in the forward direction. If it is negative this direction will be harder to travel in. If backwards is positive then it will be <b>harder</b> to travel in that direction and if negative then it will be easier.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-speed obj speed)</div>
<div class="fn-text">
Alters the speed of platforms or spikes.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-texture obj texture-name)</div>
<div class="fn-text">
Attempts to set the texture of an 'animated' object from the file with the given name. Actual result depends on the object and not all objects allows the use of a texture.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-fountain-strength obj str)</div>
<div class="fn-text">
Sets the strength of a fountain object
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-fountain-velocity obj vx vy vz)</div>
<div class="fn-text">
Sets the velcity of outgoing droplets from a fountain object
</div>
</div>

<div class="fn">
<div class="fn-proto">(score-on-death obj points)</div>
<div class="fn-text">
Score to award player when this object dies. Can be used to customize how many points to be awarded when a ball/baby/bird/cactus/player etc. dies. Passing the player argument as the object here can increse or decrease the players points when he dies.
</div>
</div>

<div class="fn">
<div class="fn-proto">(time-on-death obj time)</div>
<div class="fn-text">
Bonus time to award player when this object dies. Can be used to customize how much time to be awarded when a ball/baby/bird/cactus/player etc. dies. Passing the player argument as the object here can increse or decrease the players time when he dies.
</div>
</div>

<div class="fn">
<div class="fn-proto">(default-on-death kind points time)</div>
<div class="fn-text">
Sets the default score/time to be awarded when objects of the given kind dies. The affects only objects created <b> after </b> this function call. 'kind' must here be one of the '*score-' variables.
</div>
</div>

<h2> Creating hook objects </h2> These objects make a continous change to the game but is generally not drawn by themselves.

<div class="fn">
<div class="fn-proto">(add-cyclic-platform x1 y1 x2 y2 low high offset speed)
</div>
<div class="fn-text">
Creates a new cyclic platform which modiies the map in the region x1/y1 to x2/y2. This platform moves between the height value 'low' and 'high' with the given speed and time offset. Use offset to have platform which move out of sync (harder for the player to pass).
</div>
</div>

<div class="fn">
<div class="fn-proto">(animator length position direction A B repeat function)
</div>
<div class="fn-text">
These can be quite difficult to understand, so we shall describe these like this:
<p/> Imagine a slider together with a marker you can position anywhere on the slider. The slider has numbers on it, on the left end it starts with some number value A and ends with value B on the right end. Furthermore, the marker on the slider can have a speed moving it right (positive speed) or left (negative speed). When the marker hits one of the left/right ends it can either:
<p/>
<ol>
<li> Bounce </li>
<li> Wrap over. ie. continue from the other end </li>
<li> Stop </li>
<li> Remove the slider and everything. </li>
</ol>
Now, connected to this virtual slider is a function which is called whenever the marker has moved with the *value* which the marker currently points at.
<p/> Ok, so that is how an "animator" object works. The slider analogy is just for the explanation, nothing is displayed in the game, but you can use it to make callbacks which alters the gameworld. For some examples of what you can do with it see lv8.scm. The behaviour can be the sum of *animator-0-{remove,stop,bounce,wrap}* and *animator-1-{remove,stop,bounce,wrap}* or simply *animator-{remove,stop,bounce,wrap}* which has the same effect on both sides.
</div>
</div>

<h2> Operations on hook objects </h2> Since all animated objects are also hook objects these functions can be applied to most of the animated objects also. Eg, it is possible to "turn off" a mr-black ball, or a switch etc.

<div class="fn">
<div class="fn-proto">(set-onoff obj state)</div>
<div class="fn-text">
Turns the given hook object on or off depending on if the given state is true or not.
</div>
</div>

<div class="fn">
<div class="fn-proto">(animator-value animator)</div>
<div class="fn-text">
Returns the current value of animator object
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-animator-direction animator direction)</div>
<div class="fn-text">
Sets the speed and direction of the animator.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-animator-position animator direction)</div>
<div class="fn-text">
Sets the position (0 .. length) for the position of the slider. This is <b>not</b> the same as the value of the animator unless A/B happens to be 0/1.
</div>
</div>

<h2> Global operations </h2> These functions modify or read the global state of the game. Such as turning on fog, or making it night etc.

<div class="fn">
<div class="fn-proto">(day)</div>
<div class="fn-text">
Turns on the global light (day light).
</div>
</div>

<div class="fn">
<div class="fn-proto">(night)</div>
<div class="fn-text">
Turns off the global light, making it night time.
</div>
</div>

<div class="fn">
<div class="fn-proto">(fog [strength])</div>
<div class="fn-text">
Turns on fog in the game, with the given strength going from 0 to 2.
</div>
</div>

<div class="fn">
<div class="fn-proto">(fog-color r g b)</div>
<div class="fn-text">
Gives the red/green/blue colour of the fog.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-bonus-level next-level)</div>
<div class="fn-text">
Makes this level a "bonus level". This means that the level is exited when the player dies and no life is lost.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-track-name name)</div>
<div class="fn-text">
Gives the name of this level (aka. "track").
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-author name)</div>
<div class="fn-text">
Gives the name of the author for this track.
</div>
</div>

<div class="fn">
<div class="fn-proto">(start-time time)</div>
<div class="fn-text">
Gives the starting time, in seconds, for this track.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-time time)</div>
<div class="fn-text">
Sets the time left for the player (regardless of his current time).
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-time)</div>
<div class="fn-text">
Returns how much time the player has left.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-time time)</div>
<div class="fn-text">
Adds the given amount of time to the player.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-score score)</div>
<div class="fn-text">
Sets the score of the player.
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-score)</div>
<div class="fn-text">
Returns the current score of the player.
</div>
</div>

<div class="fn">
<div class="fn-proto">(add-score score)</div>
<div class="fn-text">
Adds the given score to the player.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-start-position x y)</div>
<div class="fn-text">
Sets the players starting position.
</div>
</div>

<div class="fn">
<div class="fn-proto">(snow strength)</div>
<div class="fn-text">
Turns on snow. Strength must be in the range 0.0 to 1.0
</div>
</div>

<div class="fn">
<div class="fn-proto">(rain strength)</div>
<div class="fn-text">
Turns on rain. Strength must be in the range 0.0 to 1.0
</div>
</div>

<div class="fn">
<div class="fn-proto">(difficulty)</div>
<div class="fn-text">
Returns the difficulty we are currently playing on as an integer in the range 0 (easy) to 2 (hard). See also the variables *easy*, *medium* and *hard* which has these values.
</div>
</div>

<div class="fn">
<div class="fn-proto">(use-grid v)</div>
<div class="fn-text">
Turns the grid on/off globally over the whole map.
</div>
</div>

<div class="fn">
<div class="fn-proto">(jump strength)</div>
<div class="fn-text">
Scales the maximum jump height of the player. If zero than the player cannot jump, if eg. 2 then he can jump twice as high as normally.
</div>
</div>

<div class="fn">
<div class="fn-proto">(scale-oxygen strength)</div>
<div class="fn-text">
Scales how long player can be under water.
</div>
</div>

<div class="fn">
<div class="fn-proto">(play-effect name)</div>
<div class="fn-text">
Plays the sound effect in the given file name.
</div>
</div>

<div class="fn">
<div class="fn-proto">(camera-angle xy z)</div>
<div class="fn-text">
Sets the cameras position as a rotation in the xy plane and in the z plane.
</div>
</div>

<div class="fn">
<div class="fn-proto">(camera-force-focus x y z)</div>
<div class="fn-text">
Immediately set a new focus position for the camera. (May be useful when
teleporting the player a long distance.)
</div>
</div>

<div class="fn">
<div class="fn-proto">(clear-song-preferences)</div>
<div class="fn-text">
Removes all old music preferences.
</div>
</div>

<div class="fn">
<div class="fn-proto">(force-next-song)</div>
<div class="fn-text">
Force a reload of songs.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-song-preference song weight)</div>
<div class="fn-text">
Sets the weight for playing the given song.
</div>
</div>

<h2> Callbacks </h2> General callback (hook) functions.

<div class="fn">
<div class="fn-proto">(trigger x y radius function)</div>
<div class="fn-text">
Call the given function each tick when the player is within given radius from x/y.
</div>
</div>

<div class="fn">
<div class="fn-proto">(smart-trigger x y entering-fn leaving-fn)</div>
<div class="fn-text">
Call the given functions when the player enters or leaves the given radius from the given position.
</div>
</div>

<div class="fn">
<div class="fn-proto">(on-event event subject function)</div>
<div class="fn-text">
Register a function to be called when the given event occurs for the given object. Callback must accept two arguments (subject and object). Subject must be of type 'animated' or of type 'gameHook', object is only used for some events (giving eg. who killed the subject) and is otherwise false.
</div>
</div>

<div class="fn">
<div class="fn-proto">(get-event-callback)</div>
<div class="fn-text">
Returns the callback currently registerd to the given object and event.
</div>
</div>

<h2> Map operations </h2> These operations makes changes to the terrain of the level and can be used to create custom events on the map.

<div class="fn">
<div class="fn-proto">(set-cell-flag x0 y0 x1 y1 flag state)</div>
<div class="fn-text">
Turns on/off the given flag in all cells in the region x0/y0 to x1/y1. Flag must here be one of the '*cell-' flags. See the list of built-in variables for a list of suitable flags to modify.
<p/> Can be used to eg. dynamically change a region of the map to be icy, or an acid etc.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-cell-velocity x0 y0 x1 y1 vx vy)</div>
<div class="fn-text">
Modifies the velociy of the given cells. This is used primarily by cells which have the "track" property set.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-cell-heights x0 y0 x1 y1 h0 h1 h2 h3 h4)</div>
<div class="fn-text">
Modifies the height of the given cells. The heights are given as five values corresponding to the four corners and the center point of the cell.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-cell-water-heights x0 y0 x1 y1 h0 h1 h2 h3 h4)</div>
<div class="fn-text">
Modifies the water height of the given cells. If the water height is higher than the normal height of a cell then it is under water. The heights are given as five values corresponding to the four corners and the center point of the cell.
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-cell-colors x0 y0 x1 y1 corner r g b a)</div>
<div class="fn-text">
Modifies the color of <b> one </b> corner of each of the given cells. The corner modified is given by 'corner' and corresponds to one of the '*cell-' flags with a direction (eg. *cell-ne*).
</div>
</div>

<div class="fn">
<div class="fn-proto">(set-cell-wall-colors x0 y0 x1 y1 corner r g b a)</div>
<div class="fn-text">
Modifies the wall color of <b> one </b> corner of each of the given cells. The corner modified is given by 'corner' and corresponds to one of the '*cell-' flags with a direction (eg. *cell-ne*).
</div>
</div>

<div class="fn">
<div class="fn-proto">(copy-cells x0 y0 x1 y1 x2 y2 flipx flipy transpose)</div>
<div class="fn-text">
Copies the region of cells from x0/y0 to x1/y1 inclusive so that x0/y0 gets mapped to the coordinate x2/y2. The boolean parameters 'flipx', 'flipy', and 'transpose' permit simple transformations (such as rotations when two of the three parameters are true) on the region before it is pasted at x2/y2.
</div>
</div>

<h2> Constants </h2> These functions modify or read the global state of the game. Such as turning on fog, or making it night etc.

<div class="fn">
<div class="fn-proto">*mod-speed* *mod-jump* *mod-spike* *mod-glass* *mod-dizzy* *mod-frozen* *mod-float* *mod-extra-life* *mod-large* *mod-small* *mod-nitro* </div>
<div class="fn-text">
Specifices modifications to be applied to a ball or to a modpill.
</div>
</div>

<div class="fn">
<div class="fn-proto">*easy* *normal* *hard*</div>
<div class="fn-text">
Difficulty levels returned by the (difficulty) function.
</div>
</div>

<div class="fn">
<div class="fn-proto">*ff-nothing* *ff-kill1* *ff-bounce1* *ff-kill2* *ff-bounce2* *ff-kill* *ff-bounce* </div>
<div class="fn-text">
Specifies the behaviour of forcefields when moving through them in direction 1 or direction 2. Use eg. (+ *ff-kill1* *ff-bounce2*) to die when moving in direction 1 and bounce when moving in direction 2.
</div>
</div>

<div class="fn">
<div class="fn-proto">*soft-enter* *soft-exit*</div>
<div class="fn-text">
Flags to be given to pipes to make it easier to enter/exit them.
</div>
</div>

<div class="fn">
<div class="fn-proto">*cell-ice* *cell-acid* *cell-sand* *cell-kill* *cell-trampoline* *cell-nogrid* *cell-track*</div>
<div class="fn-text">
Flags that can be given to cells modifying the terrain on them.
</div>
</div>

<div class="fn">
<div class="fn-proto">*animator-0-remove* *animator-0-stop* *animator-0-bounce* *animator-0-wrap* *animator-1-remove* *animator-1-stop* *animator-1-bounce* *animator-1-wrap* *animator-remove* *animator-stop* *animator-bounce* *animator-wrap*</div>
<div class="fn-text">
Specify the behaviour of an animator objects movement based on a sum of these values.
</div>
</div>

<div class="fn">
<div class="fn-proto">*cell-ne* *cell-nw* *cell-se* *cell-sw* *cell-center*
</div>
<div class="fn-text">
Gives the different corners of a cell.
</div>
</div>

<div class="fn">
<div class="fn-proto">*bird-constant-height*</div>
<div class="fn-text">
If this flag is set to true for a bird then it will always fly at the same height (not following the terrain).
</div>
</div>

<div class="fn">
<div class="fn-proto">*death* *spawn* *tick*</div>
<div class="fn-text">
Events for which it is possible to trigger callbacks on most animated objects. For now only the *death* events are working.
</div>
</div>

<div class="fn">
<div class="fn-proto">*score-player* *score-black* *score-baby* *score-bird* *score-cactus* *score-flag* </div>
<div class="fn-text">
Specifies a type of animated object to be used with the default-on-death function.
</div>
</div>

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