This is the fifth part of Egretia Engine tutorial, showing how to build a space shooter game!
Part 1 https://bit.ly/32xy7r3
Part 2 https://bit.ly/2CV2CfC
Part 3 https://bit.ly/39uicLD
Part 4 https://bit.ly/3jJui8p
Demonstration
Programming
>Explosion
1）TX
public id:number; //Type
public vis:boolean; //vis is necessary in Factory pattern
public fi:number; //which animation frame it will play
public t:number; //timer, such as three passes of main loop
public m:number; //state
public l:number; //how long it will last
public tm:TXManager; // parent pointer
Constructor:
if(this.t > 0){
// it will be invisible in the storage system
//0 means “Get ready”， 1 means “Play”
this.visible = false;
this.m = 0;
}else{
this.visible = true;
this.m = 1 ;
}
TX
“`c
class TX extends egret.Sprite{
public im:egret.Bitmap;
public id:number; //Type
public vis:boolean; // vis is necessary in Factory pattern
public fi:number; // which animation frame it will play
public t:number; // timer, such as three passes of main loop
public m:number; //state
public l:number; // how long it will last
public tm:TXManager; // parent pointer
public constructor(id:number,x:number, y:number,
t:number,l:number,tm:TXManager) {
super();
this.id = id;
this.x = x ;
this.y = y;
this.t = t;
this.l = l;
this.m = 0;
this. fi = 0 ;
this.vis = true; // =false , the objects will disappear in the factory
this.tm = tm;
this.im = Main.createBitmapByName(“tx1_1_png”);
this.anchorOffsetX = this.im.width/2;
this.anchorOffsetY = this.im.height/2;
this.addChild(this.im);
if(this.t > 0){
//it will be invisible in the storage system
//0 means “Get ready”， 1 means “Play”
this.visible = false;
this.m = 0;
}else{
this.visible = true;
this.m = 1 ;
}
}
public update(){
switch(this.m ){
//
case 0:
//timer
this.t — ;
if(this.t <=0 ){
//explode
this.visible = true;
this.m = 1; //play
}
break;
case 1 :
//start the animation
this.fi++;
//
if(this.fi >= this.l){
this.vis =false; //object destruction
}else{ //if it’s not over, switch frame
//switch frame: fi from 0 to 9，
//10 is the number of photos, fi is the animation frame, 1 is the length
this.im.texture = RES.getRes(“tx1_”+Math.floor(this.fi*10/this.l + 1)+”_png”);
}
}
}
}
TXManager
class TXManager extends egret.Sprite{
public tm:Array<TX>; //Array: to add or remove objects
public game:MainGame;
public constructor(game:MainGame) {
super();
this.game = game;
this.tm = new Array();
}
//each create needs one new
public create(id:number,x:number,y:number,t:number,l:number,game:MainGame){
//create bullet
let one = new TX(id,x,y,t,l,this);
// add to the world
this.addChild(one);
//put it at the end of array
this.tm.push(one);
}
//find out and update all the bullets
public update(){
//the total length of storage system. Find out all of bullets by loop
for(let i = 0 ; i < this.tm.length ; i++){
// find out each bullet
let one = this.tm[i];
one.update();
//the extra bullets need to be removed
// bullets are out of screen ，vis == false.remove
if(one.vis == false){
//remove it from the scene firstly
this.removeChild(one);
//then remove it from storage system
this.tm.splice(i ,1);
//remove an object，length -1
i — ;
}
}
}
}
ZDManager
if(npc.hp <= 0 ){
for(let k = 0 ; k < 10 ; k ++){ //-50 to +50
this.game.tm.create( 0, npc.x + Math.random()*100 -50 ,
npc.y + Math.random()*100 -50 ,
Math.floor(Math.random() * 5), 10,this.game);
}
npc.vis = false;
>Effects of explosion
Add the following codes to NPC0，1
public dead(){
for(let k = 0 ; k < 10 ; k ++){
this.nm.game.tm.create( 0, this.x + Math.random()*100–50 ,
this.y + Math.random()*100–50 ,
Math.floor(Math.random() * 5), 10,this.nm.game);
}
}
then
>BOSS0
class BOSS0 extends NPC{
public im:egret.Bitmap;
public m:number;
public t:number;
public constructor(x:number,y:number,nm:NPCManager) {
super(nm);
this.x = x ;this.y = y;
this.im = Main.createBitmapByName(“boss50_png”);
this.im.anchorOffsetX = this.im.width/2;
this.im.anchorOffsetY = this.im.height/2;
this.addChild(this.im);
this.m = this.t = 0;
this.hp = 1000;
}
public update(){
}
public isHit(x:number,y:number):boolean{
return false;
}
public dead(){
}
}
Add BOSS
switch(this.m){
//where boss stops
case 0:
this.y+=10;
if(this.y >= 150){
this.t = 20 ;
this.m = 1;
}
break;
//break
case 1:
this.t — ;
if(this.t <=0){
this.m = 10;
this.t = 0 ;
}
break;
//set off the bullet
case 10:
this.t++;
// fire a single bullet every three passes of main loops
if(this.t % 3 == 0 ){
for(let i = 0 ; i < 5 ; i++){
//bullets in five rows
//160+i*10 fire a single bullet every angle of 10
this.nm.game.nzm.create(1, this.x, this.y, 10 ,160+i*10,this.nm.game );
}
}
if(this.t >= 20){
this.t = 10;
this.m = 1;
}
break;
}
Single bullet
Round-shaped bullet
//fire the bullet
case 10:
this.t++;
//fire a single bullet every three passes of main loop
if(this.t % 3 == 0 ){
for(let i = 0 ; i < 36 ; i++){
//bullets in five rows
//160+i*10 fire a single bullet every angle of 10
this.nm.game.nzm.create(1, this.x, this.y, 10 ,160+i*10,this.nm.game );
}
}
if(this.t >= 20){
this.t = Math.random()* 20 + 10;
this.m = 1;
}
break;
Swirl Bullet
case 11:
this.t++;
// the angle of bullets will change as t++ alters
this.nm.game.nzm.create(1, this.x, this.y, 10 ,180+this.t*10,this.nm.game ); //
Counterclockwise
this.nm.game.nzm.create(1, this.x, this.y, 10 ,180 — this.t*10,this.nm.game ); // clockwise
//fire the bullet every angle of 10
if(this.t >= 36){
this.t = Math.random()* 20 + 10;
this.m = 1;
}
break;
Matrix bullet
case 12:
this.t++;
//15，16，17，18，19 fire 5 bullets
if(this.t % 20 > 14){
for(let i = 0 ; i < 5 ; i++){
// fire a row every 20 degrees, 5 bullets from 130 degrees
//this.t/10，the result of top ten:10，11，12，13 when it comes to 1，the length = roundness*20
this.nm.game.nzm.create(1,this.x,this.y,10,Math.floor(this.t/20)*20 +130+i*5,this.nm.game );
// fire 5 bullets at 135 degree
}
}
if(this.t >= 100){
this.t = Math.random() * 20 + 10;
this.m =1 ;
}
break;
Whip-shaped bullets
// Whip bullet
case 13:
this.t++;
// the speed will increase as the time changes
this.nm.game.nzm.create( 1, this.x — 50, this.y, 6 + this.t *2 ,190 — this.t,this.nm.game );
this.nm.game.nzm.create( 1, this.x+50, this.y, 6 + this.t *2 ,170 + this.t,this.nm.game );
if(this.t >= 10){
this.t = Math.random() * 20 + 10;
this.m =1 ;
}
break;
Bullets Based on Orientation
Code:
// if n is null or empty, there is no value assigned
if(!n){
n = Math.atan2(this.game.player.x — x,y — this.game.player.y);
//note: convert the radians to degrees
n = n * 180/Math.PI;
}
BOSS0
//bullets based on orientation
case 14 :
this.t++;
// fire the bullets every ten passes of main loop
if(this.t % 10 > 4){
this.nm.game.nzm.create( 1, this.x — 50, this.y, 15);
}
if(this.t >= 50){
this.t = Math.random() * 20 + 10;
this.m =1 ;
}
break;
Random bullets
case1 this.m = Math.floor(Math.random() * 5 ) + 10; //random bullets
>Collision detection of irregular shapes
W 146 H166 73，83 pixels
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