This is the second part of Egretia Engine tutorial, showing how to build a space shooter game!
Part 1 https://bit.ly/32xy7r3
Demonstration
Programming
>Bullet
Speed principle:
Error
Wrong code
Correction:
1this.bg = new BG(this);
2this.player = new Player(this);
3// x,y, speed，angle
4this.zd = new ZD(this.player.x,this.player.y, 20 ,30,this);
5
6this.addChild(this.bg);
7this.addChild(this.zd);
8this.addChild(this.player);
9
>Factory Pattern
Core: objects creation
In Factory pattern, we create object which will be stored in the factory’s storage system.
New object creation will be allocated and returned in the storage system, but the objects will be removed when certain conditions are met.
If you use the factory pattern to manage object, the object must have a property:
The visible (vis) property: The boolean type represents whether it can still be stored in the factory.
vis== false. This object will be removed in order to ensure that storage system is not full
vis == true means that it can be stored.
Bullet update:
>ZDManager
1public create(x:number,y:number,v:number,n:number,game:MainGame){
2 //create bullet
3 let one = new ZD(x,y,v,n,game);
4 //add
5 this.addChild(one);
6 // to the end of array
7 this.zm.push(one);
8 //
9 }
Update principles
1public update(){
2 // the total length
3 for(let i = 0 ; i < this.zm.length ; i++){
4 // find each bullet
5 let one = this.zm[i];
6 one.update();
7 // remove the extra bullets
8 // if bullet is off the screen ，vis == false, remove
9 if(one.vis == false){
10 //remove it from the scene
11 this.removeChild(one);
12 //remove it from the storage system
13 this.zm.splice(i ,1);
14 //remove one item, the length -1
15 i — ;
16 }
17 }
18}
Maingame update principles
1 public update()
2 {
3 this.bg.update();
4 this.player.update();
5 this.zm.update();
6 //time interval
7 this.t++;
8 if(this.t >= 4){
9 //after the creation is called, the bullet will occur
10 //add two more ballistic paths, there are five paths in total
11 this.zm.create(this.player.x,this.player.y,20,0, this );
12 this.zm.create(this.player.x,this.player.y,20,-15, this );
13 this.zm.create(this.player.x,this.player.y,20,-30, this );
14 this.zm.create(this.player.x ,this.player.y,20,15, this );
15 this.zm.create(this.player.x,this.player.y,20,30, this );
16 this.t = 0;
17 }
18 }
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