Imagine that you are creating a little game for your space (Croquet is not a game engine but it's viable for the creation of simple minigames).

In the game, a "shooter" try to kill many "monsters" (HalfLife3?). And you would like to create an score, showing how many "monsters" are dead.

TIP: There are more "serious" applications for this convergence 3D-2D, like, by example: a virtual galery of sculptures. When the avatar is near (use of "distance") an sculpture, appears a description about it. Different ambient sounds for each sculpture... Etc. Etc. Use your imagination!

In this lessons you will learn how to do it.

IMPORTANT: I hope that you understood all the concepts of the "Basic Tutorial for Beginners because they are pre-requirements for these lessons.

Until now we have created "instances variable" of a Class. But for our application we need to create a: Class variable.

When we change the value of a Class variable in any instance of the Class, this value will be changed at all the instances .

We will do an exercice using some of the resources we have created at previous lessons. So, the new definition of the Class Private will be:

 
TeapotMorph subclass: #Private
	instanceVariableNames: 'tframe cworld sceneObjects floor world space contacts prevTime
         rnd  wD12x7x1a wD12x7x1abody ahead   cL4x6x4a cL4x6x4abody on 
          cL4x6x4afly  lG shot bulletInitT bulletInitO shotS expS recS  '
	classVariableNames: 'Score' 
	poolDictionaries: 'OpenGLConstants '
	category: 'MyCroquet' 

A Class variable is always "capitalized" (first letter in upper case).

Like Smalltalk doesn't have the usual concept of properties (like Java, C++ etc.) we need to create 2 new methods to access this Class variable. To "read" and "write":

score

^  Score.

And to "write":

score:aScore.

Score:= aScore.

In the initializeDefaultSpace method we initialize the variable with: zero (in red).

 
initializeDefaultSpace
	 
| base|
 on:=0. 
cL4x6x4afly:=0.
shot:=0.

 Score := 0.

"Loading the sound files" 
shotS:=StreamingMP3Sound onFileNamed:  
 (FileDirectory pathFrom:
           {FileDirectory default pathName.  'Content'. 'legoicMGunODE' .'gunshot2.mp3'}) . 
expS:=StreamingMP3Sound onFileNamed:  
 (FileDirectory pathFrom:
           {FileDirectory default pathName.  'Content'. 'legoicMGunODE' .'explosion2.mp3'}) . 
recS:=StreamingMP3Sound onFileNamed:  
 (FileDirectory pathFrom:
           {FileDirectory default pathName.  'Content'. 'legoicMGunODE' .'gunrecharging.mp3'}) . 

cworld := TSpace new.
self makeLight: cworld.
	 
base :=BasePlateA70x3x70 new.
base translationX: 0 y: -6.3  z: 0.
cworld addChild: base.
 
prevTime := Time millisecondClockValue.
world := ODEWorld new.
space := ODESpace new.
world add: (contacts := ODEContactGroup new).
sceneObjects := Dictionary new.
rnd := Random new.
	
lG := LegoicMGunODE  new. 
lG translationX: 0 y: -2  z: 0.
cworld addChild: lG.
world add: (lG body).
space add: (lG geom).
sceneObjects at:lG body id put: {lG. lG body.  lG geom}.

bulletInitT:= lG bullet translation.
bulletInitO:= lG bullet orientation. 

self addCube.  "required"
self transferCam: lG.
^ cworld 

Our exercice will be very simple. At this lesson we will create a Text-border and to do an script glued to it, where we will create an instance of the Class Private, whose name will be: pr. Look the figure:

IMPORTANT: If you are not understanding nothing that you are seeing it's because you need to read again the: "Basic Tutorial for Beginners.

The code of the script1 is:

 
| pr |
pr:=Private new.
self setCharacters: pr score.

This script will run when the user "mouseEnter" the Text-border, actualizing the value of the score.

We would like that: when the shooter do a "good shot" against the column, the score is increased by 1.

We need to code this (in red) at the stepAt method:

stepAt: currentTime

| dur nCollision|
super step.

 cL4x6x4a ifNotNil:[
 cL4x6x4a logo addRotationAroundY: 1.
 (cL4x6x4afly=1)ifTrue:[
   cL4x6x4abody linearVel:  5@ 5@ -5.
   cL4x6x4abody angularVel:  5@ 0.5@ -5. 
 ]
]. 
	
 wD12x7x1a ifNotNil:[
 wD12x7x1abody  position:28.0@0.50@-26.0.
 wD12x7x1abody rotationAroundZ:0.
]. 

 (shot=1) ifTrue:[
 lG  bullet translation: lG  bullet translation + (lG  bullet localTransform column3*-2). " A good velocity..."

 ((lG bullet distanceTo: lG)>20) ifTrue:[
   lG bullet translation: bulletInitT .
   lG bullet orientation: bulletInitO.
   recS play.
   shot:=0.
  ].
  (cL4x6x4a)ifNotNil:[
   ((lG bullet distanceTo: cL4x6x4a)<4) ifTrue:[ "What to do in the collision"
     cL4x6x4abody linearVel:  5@ 5@ -5.
     cL4x6x4abody angularVel:  5@ 0.5@ -5. 
     expS play.
     Score := Score+1. 
     lG bullet translation: bulletInitT .
     lG bullet orientation: bulletInitO.
     recS play.
     shot:=0.
   ].
  ].
].	
 	
 
space ifNil: [^self  ].
world connect.
space connect.
dur := ((currentTime asFloat) - (prevTime asFloat)) / 1000.
prevTime := currentTime.
sceneObjects do:[:id|
  | each body |
  each := id at:1. 
  body := id at:2.
  each isStepping not ifTrue:[
  each localTransform: body transform transposed.
 ]
 ifFalse:[ 
  body linearVel:  each globalPosition - (body position) * 10.	
  body position: each globalPosition.
  body quaternion: (each quaternion)
 ]
].
space collideDo: [:geom1 :geom2 |  
 nCollision := contacts
 addContact: geom1
 with: geom2
 bounce: 0.1 
 bounceVel: 0.1
 softCFM: 0.1.
 nCollision > 0 ifTrue: [
  wD12x7x1a ifNotNil:[ 
  
  self verifycL4x6x4a. 
 
  (ahead=true & on=0 ) ifTrue:[
   lG translationX: 0 y: -2  z: 0.
  ].
  (ahead=false & on=0 ) ifTrue:[
    lG translationX: 0 y: -2  z: 0.
   ].	
  (ahead=true  & on=1) ifTrue:[
    lG  translation:lG translation + (lG localTransform column3*0.5). 
  ].
  (ahead=false  & on=1 ) ifTrue:[
    lG  translation: lG translation - (lG localTransform column3*0.5). 
  ]. 	 
 
]].
].

world quickStep: dur.  
contacts empty.

Only this... Very easy.

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