Script Classes for Adventure Games/Motion Classes - Revision history

Andrew Branscom: /* Also See */

2026-01-16T02:42:33Z

Also See

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	* [[:Category:SCI Classes\|SCI Classes]]		* [[:Category:SCI Classes\|SCI Classes]]
	* [[:Category:Animation Articles\|Animation Articles]]		* [[:Category:Animation Articles\|Animation Articles]]
	* [[:Category:SCI Animation ~~Articles~~\|SCI Animation Articles]]		* [[:Category:SCI Animation\|SCI Animation Articles]]
	* [[:Category:SCI Motion Class\|The SCI Motion Class]]		* [[:Category:SCI Motion Class\|The SCI Motion Class]]
	* [[SCI Specifications]]		* [[SCI Specifications]]

Andrew Branscom: /* Also See */

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Also See

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	[[Category:SCI Motion Class x Property]]		[[Category:SCI Motion Class x Property]]
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 [[Script Classes for Adventure Games/Global Variables|27]] |
 [[Script Classes for Adventure Games/Index|Index]]
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+<div align="center"><span style="font-size: 22pt">The Motion Classes</span><br />''Author: [[Jeff Stephenson]]''<br />''1988-04-05''</div></div>
 ==<br /> The Motion Classes ==
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 ==<br /> References ==
-<references />
+<references /><!-- Do not edit this section. It is autopopulated by <ref></ref> tags -->
-==<br /> See Also: ==
+==<br /> Also See ==
 * [[SCI Specifications]]
 &nbsp;
 [[Script Classes for Adventure Games | Table of Contents]]
 <span style="float: left">[[Script Classes for Adventure Games/Cycling Classes|&lt; Previous: The Cycling Classes]]</span>
 <span style="float: right">[[Script Classes for Adventure Games/Avoider Class|Next: The Avoider Class &gt;]]</span>
 &nbsp;
 [[Category:References]]
 [[Category:SCI References]]
 [[Category:Documentation]]
 [[Category:SCI Documentation]]
 [[Category:Scripting]]
 [[Category:SCI Scripting]]
 [[Category:Classes]]
 [[Category:SCI Classes]]

Andrew Branscom at 01:53, 15 January 2026

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	===<br /> Path ===		===<br /> Path ===

	~~<blockquote>~~
	This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The points of the Path are specified in a local array.		This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The points of the Path are specified in a local array.

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	<blockquote>(ego posn:100 100, setMotion: squarePath obj1 obj2)</blockquote>		<blockquote>(ego posn:100 100, setMotion: squarePath obj1 obj2)</blockquote>
	~~</blockquote>~~

	===<br /> RelPath ===		===<br /> RelPath ===

Andrew Branscom: /* Path */

2026-01-15T01:52:26Z

Path

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	===<br /> Path ===		===<br /> Path ===

			<blockquote>
	This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The points of the Path are specified in a local array.		This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The points of the Path are specified in a local array.

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	<blockquote>(ego posn:100 100, setMotion: squarePath obj1 obj2)</blockquote>		<blockquote>(ego posn:100 100, setMotion: squarePath obj1 obj2)</blockquote>
			</blockquote>

	===<br /> RelPath ===		===<br /> RelPath ===

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Andrew Branscom at 00:01, 12 April 2018

2018-04-12T00:01:58Z

New page

[[Official SCI Documentation]] 
[[Script Classes for Adventure Games | Table of Contents]]

<div align="center">
Chapter:
[[Script Classes for Adventure Games/Introduction|1]] |
[[Script Classes for Adventure Games/RootObj Class|2]] |
[[Script Classes for Adventure Games/Object Class|3]] |
[[Script Classes for Adventure Games/Collection Class|4]] |
[[Script Classes for Adventure Games/Script Class|5]] |
[[Script Classes for Adventure Games/Timer Class|6]] |
[[Script Classes for Adventure Games/Feature Class|7]] |
[[Script Classes for Adventure Games/View Class|8]] |
[[Script Classes for Adventure Games/PicView Class|9]] |
[[Script Classes for Adventure Games/Cycling Classes|10]] |
[[Script Classes for Adventure Games/Motion Classes|11]] |
[[Script Classes for Adventure Games/Avoider Class|12]] |
[[Script Classes for Adventure Games/Event Class|13]] |
[[Script Classes for Adventure Games/User Class|14]] 
[[Script Classes for Adventure Games/Game Class|15]] |
[[Script Classes for Adventure Games/Locale Class|16]] |
[[Script Classes for Adventure Games/Region Class|17]] |
[[Script Classes for Adventure Games/Room Class|18]] |
[[Script Classes for Adventure Games/Timer2 Class|19]] |
[[Script Classes for Adventure Games/InvItem Class|20]] |
[[Script Classes for Adventure Games/Block Class|21]] |
[[Script Classes for Adventure Games/Cage Class|22]] |
[[Script Classes for Adventure Games/Sound Class|23]] |
[[Script Classes for Adventure Games/StatusLine Class|24]] |
[[Script Classes for Adventure Games/File Class|25]] |
[[Script Classes for Adventure Games/Code Class|26]] |
[[Script Classes for Adventure Games/Global Variables|27]] |
[[Script Classes for Adventure Games/Index|Index]]
</div> 

<div align="center">The Motion Classes 
''Author: [[Jeff Stephenson]]'' 
''Date: 5 April 1988''</div>

 

== The Motion Classes ==

The sub-classes of class Motion implement the various kinds of motion which Actors can execute.

=== Motion ===

The Motion class is the basis for all the specialized motions. If a caller is specified in the setMotion: for a motion, it will be notified of the motion's completion by being sent the cue: message.

{|
|width= "125"|In file:||motion.sc
|-
|Inherits from:||Object
|-
|Inherited by:||MoveTo
|-
| ||Wander
|-
| ||Chase
|-
| ||Follow
|-
| ||Jump
|-
| ||Orbit
|-
| ||Path
|}

==== Properties ====

<blockquote>
===== x =====

===== y =====
<blockquote>The coordinates towards which the Actor is moving.</blockquote>

===== client =====
<blockquote>The Actor being moved by the instance of motion.</blockquote>

===== caller =====
<blockquote>The object to cue: when the motion is complete.</blockquote>

===== dx dy b-moveCnt b-i1 b-i2 b-di b-xAxis b-incr =====
<blockquote>These properties are used internally by the modified Bresenham line algorithm which moves the Actors.</blockquote>
</blockquote>

==== Methods ====

<blockquote>
===== moveDone =====
<blockquote>Executed when the motion completes or is blocked. Cue:s the caller, if there was one, and dispose:s of the motion class.</blockquote>
</blockquote>

=== MoveTo ===
The MoveTo class just moves an object to a particular position. An Actor is moved to a position with (actor setMotion: MoveTo x y [caller]).

{|
|width= "125"|In file:||motion.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||none
|}

=== Wander ===

The Wander motion class implements a random wander for Actors. It is invoked for an Actor by (actor setMotion: Wander [distance]) where the optional argument, distance, is the maximum distance of a leg of the wander (default is 20 pixels). This motion never completes — the Actor will keep wandering until a new motion type is set.

{|
|width= "125"|In file:||motion.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||none
|}

==== Properties ====

<blockquote>
===== distance =====
<blockquote>The maximum distance to be wandered on a given leg of the wander.</blockquote>
</blockquote>

=== Follow ===

This class is for making one Actor follow another. It is invoked for an Actor with (actor setMotion: Follow anotherActor [distance]), where anotherActor is the Actor to be followed and the optional distance specifies how closely to follow. If actor is further from anotherActor than distance, it will start moving towards anotherActor. Otherwise it will stop moving. The default distance is 15 pixels. As for Wander, this motion never completes.

{|
|width= "125"|In file:||motion.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||none
|}

==== Properties ====

<blockquote>
===== who =====
<blockquote>The ID of the Actor being followed.</blockquote>

===== distance =====
<blockquote>The distance to try and maintain from the Actor specified by who.</blockquote>
</blockquote>

=== Chase ===

This class implements the concept of trying to catch another Actor. It is invoked with (actor setMotion: Chase anotherActor distance [caller]). As in Follow, anotherActor is the Actor to chase. Distance is the distance from anotherActor at which it is considered to be caught. When anotherActor has been caught, caller is cue:ed.

{|
|width= "125"|In file:||motion.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||none
|}

==== Properties ====

<blockquote>
===== who =====
<blockquote>The ID of the Actor being chased.</blockquote>

===== distance =====
<blockquote>The distance from who at which who is considered caught.</blockquote>
</blockquote>

=== Jump ===

This class simulates motion under a gravitational field. It is useful to make an Actor simultate a falling motion. The fall is straight down by default. This simulates, for example, falling off of a cliff. A horizontal gravitation can also be simulated by setting the gx property.

{|
|width= "125"|In file:||jump.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||JumpTo
|}

==== Properties ====

<blockquote>
===== x =====
<blockquote>x coord of finish. This property is set by the init method to reflect to clients velocity.</blockquote>

===== y =====
<blockquote>y coord of finish. This property is also set internally.</blockquote>

===== gx =====
<blockquote>gravitational acceleration in pixels/(animation cycle)**2. The default is no horizontal gravity, or 0.</blockquote>

===== gy =====
<blockquote>gravitational acceleration in pixels/(animation cycle)**2. This is set according to how intense a gravitation field you wish to have simulated. The default is 3 pixels per (animation cycle)**2, so after 1 cycle the Actor would be moving 3 pixels/animation cycle 6 after 2 cycles etc.</blockquote>

===== xStep =====
<blockquote>horizontal step size. Used by Jump to calculate next position.</blockquote>

===== yStep =====
<blockquote>vertical step size. Used by Jump to calculate next position.</blockquote>

===== signal =====
<blockquote>save area for client's signal bits. Don't set this property.</blockquote>

===== illegalBits =====
<blockquote>save area for illegal bits of client. Don't set this property.</blockquote>

The following two properties, when true, indicate that we are to check for motion completion only after the apogee of the motion. This is necessary if we are to be able to jump onto things. Set these to FALSE if you do NOT want this behavior.

WaitApogeeX TRUE 
waitApogeeY TRUE

===== setTest =====
<blockquote>private — set up the jump completion test.</blockquote>
</blockquote>

=== JumpTo ===

This class sets up a Jump which will reach a certain x,y position. The kernel call (SetJump) does this in order to use long integer arithmetic. The Motion can the cue: a caller to signal then completion of the jump.

{|
|width= "125"|In file:||jump.sc
|-
|Inherits from:||Jump
|-
|Inherited by:||none
|}

==== Methods ====

<blockquote>
===== init =====
<blockquote>This method is called by the Actors setMotion method. A JumpTo is initiated by, (actorNam. setMotion: JumpTo x y whoCares)
This will make an Actor jump to the coordinates x y, and then cue whoCares.</blockquote>
</blockquote>

=== Orbit ===

This class sets up an elliptical path for an Actor to follow. This allows the simulation of an object orbiting around another object. This mover takes into account the global variable perspective.

{|
|width= "125"|In file:||orbit.sc
|-
|Inherits from:||Motion
|-
|Inherited by:||none
|}

==== Properties ====

<blockquote>
===== centerObj =====
<blockquote>The object (Feature View PicView Prop or Actor) to orbit around.</blockquote>

===== radius =====
<blockquote>The radius of the orbit along its major axis (the widest part).</blockquote>

===== xTilt =====
<blockquote>The horizontal tilt of ellipse. 0 would be circular and 90 would be edge on.</blockquote>

===== yTilt =====
<blockquote>The horizontal tilt of ellipse. 0 would be circular and 90 would be edge on.</blockquote>

===== angleStep =====
<blockquote>Angle degree increment per animation cycle.</blockquote>

===== winding =====
<blockquote>The direction of the orbit. clockwise=1 counterclockwise=-1</blockquote>

===== curAngle =====
<blockquote>Where the Actor will be along the Orbit. 0=north, 90=east etc.</blockquote>
</blockquote>

==== Methods ====

<blockquote>
===== init =====
<blockquote>This method is called by the Actors setMotion method. a JumpTo is initiated by,

<div class="CodeBlockHeader">Code:</div>
<syntaxhighlight lang="sci">
(anActor setMotion:
Orbit ;class Orbit or an instance of it

theCtrObj ;some object with x and y properties
theRadius ;of the orbit
theXTilt ;counterclockwise from x-axis in degrees
theYTilt ;same from y-axis
theStep ;in degrees, default is 10
theWinding ;clockwise=1 counterclockwise=-1
theAngle ;0=north, etc.
)
</syntaxhighlight>
</blockquote>
</blockquote>

=== Path ===

This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The points of the Path are specified in a local array.

{|
|width= "125"|In file:||path.sc
|-
|Inherits from:||MoveTo
|-
|Inherited by:||RelPath
|}

==== Properties ====

<blockquote>
===== intermediate =====
<blockquote>Object to cue at intermediate endpoints.</blockquote>

==== value ====
<blockquote>index into path array</blockquote>
</blockquote>

==== Methods ====

<blockquote>
===== at =====
<blockquote>Returns the nth element of control array. This method must be redefined to point to the users path array.</blockquote>

===== next =====
<blockquote>Move to next point in path. This method is used internally.</blockquote>

===== atEnd =====
<blockquote>Returns TRUE if at the end of the path. This method is used internally.</blockquote>

===== Example =====

To create a square Path (assuming that ego is positioned at 100,100) we do the following:

<div class="CodeBlockHeader">Code:</div>
<syntaxhighlight lang="sci">
(local
sPath = [
100 60
160 60
160 100
100 100
PATHEND
]
)

(instance squarePath of Path
(method (at n)
(return [sPath n])
)
)
</syntaxhighlight>
</blockquote>

The following will make ego walk the path once and cue obj1 at completion of entire path and will cue obj2 at all intermediate pts.

<blockquote>(ego posn:100 100, setMotion: squarePath obj1 obj2)</blockquote>

=== RelPath ===

This class gives the Actor a Path to follow and allows cue'ing of an object at the intermediate points as well as at the end of the path. It requires less memory than a Script and is also easier to use. The relative offsets of the Path are specified in a local array.

{|
|width= "125"|In file:||path.sc
|-
|Inherits from:||Path
|-
|Inherited by:||none
|}

=== Example ===

The following uses a RelPath to make ego do loop-the-loops across the screen:

<blockquote>
<div class="CodeBlockHeader">Code:</div>
<syntaxhighlight lang="sci">
(local
lPath = [
-10 -10
0 -10
1 -10
1 0
1 10
0 10
-10 10
PATHEND
]
)

(instance loopPath of Path
(method (at n)
(return [lPath n])
)
)
</syntaxhighlight>
 
<div class="CodeBlockHeader">Code:</div>
<syntaxhighlight lang="sci">
(instance rm1 of Room
(properties
picture 1
)

(method (init)
(ego
posn: 60 100,
init:,
setMotion: aPath self
)
(super init:)
)

(method (cue)
(ego setMotion: aPath self)
)
)
</syntaxhighlight>
</blockquote>

== References ==

<references />

== See Also: ==

* [[SCI Specifications]]

 

[[Script Classes for Adventure Games | Table of Contents]]

[[Script Classes for Adventure Games/Cycling Classes|< Previous: The Cycling Classes]]
[[Script Classes for Adventure Games/Avoider Class|Next: The Avoider Class >]]

 

[[Category:References]]
[[Category:SCI References]]
[[Category:Documentation]]
[[Category:SCI Documentation]]
[[Category:Scripting]]
[[Category:SCI Scripting]]
[[Category:Classes]]
[[Category:SCI Classes]]

← Older revision		Revision as of 21:42, 15 January 2026
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	* [[:Category:SCI Classes\|SCI Classes]]		* [[:Category:SCI Classes\|SCI Classes]]
	* [[:Category:Animation Articles\|Animation Articles]]		* [[:Category:Animation Articles\|Animation Articles]]
	* [[:Category:SCI Animation ~~Articles~~\|SCI Animation Articles]]		* [[:Category:SCI Animation\|SCI Animation Articles]]
	* [[:Category:SCI Motion Class\|The SCI Motion Class]]		* [[:Category:SCI Motion Class\|The SCI Motion Class]]
	* [[SCI Specifications]]		* [[SCI Specifications]]