怎樣在android游戲開發實現粒子爆炸效果

給大家解說怎樣在android游戲開發實現粒子爆炸效果

[java]
package net.obviam.particles.model; 
 
import android.graphics.Canvas; 
import android.graphics.Rect; 
import android.util.Log; 
 
public class Explosion { 
 
    private static final String TAG = Explosion.class.getSimpleName(); 
     
    public static final int STATE_ALIVE     = 0;    // at least 1 particle is alive  
    public static final int STATE_DEAD      = 1;    // all particles are dead  
     
    private Particle[] particles;           // particles in the explosion  
    private int x, y;                       // the explosion's origin  
    private float gravity;                  // the gravity of the explosion (+ upward, - down)  
    private float wind;                     // speed of wind on horizontal  
    private int size;                       // number of particles  
    private int state;                      // whether it's still active or not  
     
    public Explosion(int particleNr, int x, int y) { 
        Log.d(TAG, "Explosion created at " + x + "," + y); 
        this.state = STATE_ALIVE; 
        this.particles = new Particle[particleNr]; 
        for (int i = 0; i < this.particles.length; i++) { 
            Particle p = new Particle(x, y); 
            this.particles[i] = p; 
        } 
        this.size = particleNr; 
    } 
     
    public Particle[] getParticles() { 
        return particles; 
    } 
    public void setParticles(Particle[] particles) { 
        this.particles = particles; 
    } 
    public int getX() { 
        return x; 
    } 
    public void setX(int x) { 
        this.x = x; 
    } 
    public int getY() { 
        return y; 
    } 
    public void setY(int y) { 
        this.y = y; 
    } 
    public float getGravity() { 
        return gravity; 
    } 
    public void setGravity(float gravity) { 
        this.gravity = gravity; 
    } 
    public float getWind() { 
        return wind; 
    } 
    public void setWind(float wind) { 
        this.wind = wind; 
    } 
    public int getSize() { 
        return size; 
    } 
    public void setSize(int size) { 
        this.size = size; 
    } 
     
    public int getState() { 
        return state; 
    } 
 
    public void setState(int state) { 
        this.state = state; 
    } 
 
    // helper methods -------------------------  
    public boolean isAlive() { 
        return this.state == STATE_ALIVE; 
    } 
    public boolean isDead() { 
        return this.state == STATE_DEAD; 
    } 
 
    public void update() { 
        if (this.state != STATE_DEAD) { 
            boolean isDead = true; 
            for (int i = 0; i < this.particles.length; i++) { 
                if (this.particles[i].isAlive()) { 
                    this.particles[i].update(); 
                    isDead = false; 
                } 
            } 
            if (isDead) 
                this.state = STATE_DEAD;  
        } 
    } 
     
    public void update(Rect container) { 
        if (this.state != STATE_DEAD) { 
            boolean isDead = true; 
            for (int i = 0; i < this.particles.length; i++) { 
                if (this.particles[i].isAlive()) { 
                    this.particles[i].update(container); 
//                  this.particles[i].update();  
                    isDead = false; 
                } 
            } 
            if (isDead) 
                this.state = STATE_DEAD;  
        } 
    } 
 
    public void draw(Canvas canvas) { 
        for(int i = 0; i < this.particles.length; i++) { 
            if (this.particles[i].isAlive()) { 
                this.particles[i].draw(canvas); 
            } 
        } 
    } 
} 

package net.obviam.particles.model;

import android.graphics.Canvas;
import android.graphics.Rect;
import android.util.Log;

public class Explosion {

 private static final String TAG = Explosion.class.getSimpleName();
 
 public static final int STATE_ALIVE  = 0; // at least 1 particle is alive
 public static final int STATE_DEAD   = 1; // all particles are dead
 
 private Particle[] particles;   // particles in the explosion
 private int x, y;      // the explosion's origin
 private float gravity;     // the gravity of the explosion (+ upward, - down)
 private float wind;      // speed of wind on horizontal
 private int size;      // number of particles
 private int state;      // whether it's still active or not
 
 public Explosion(int particleNr, int x, int y) {
  Log.d(TAG, "Explosion created at " + x + "," + y);
  this.state = STATE_ALIVE;
  this.particles = new Particle[particleNr];
   for (int i = 0; i < this.particles.length; i++) {
   Particle p = new Particle(x, y);
   this.particles[i] = p;
  }
   this.size = particleNr;
 }
 
 public Particle[] getParticles() {
  return particles;
 }
 public void setParticles(Particle[] particles) {
  this.particles = particles;
 }
 public int getX() {
  return x;
 }
 public void setX(int x) {
  this.x = x;
 }
 public int getY() {
  return y;
 }
 public void setY(int y) {
  this.y = y;
 }
 public float getGravity() {
  return gravity;
 }
 public void setGravity(float gravity) {
  this.gravity = gravity;
 }
 public float getWind() {
  return wind;
 }
 public void setWind(float wind) {
  this.wind = wind;
 }
 public int getSize() {
  return size;
 }
 public void setSize(int size) {
  this.size = size;
 }
 
 public int getState() {
  return state;
 }

 public void setState(int state) {
  this.state = state;
 }

 // helper methods -------------------------
 public boolean isAlive() {
  return this.state == STATE_ALIVE;
 }
 public boolean isDead() {
  return this.state == STATE_DEAD;
 }

 public void update() {
  if (this.state != STATE_DEAD) {
   boolean isDead = true;
   for (int i = 0; i < this.particles.length; i++) {
    if (this.particles[i].isAlive()) {
     this.particles[i].update();
     isDead = false;
    }
   }
   if (isDead)
    this.state = STATE_DEAD;
  }
 }
 
 public void update(Rect container) {
  if (this.state != STATE_DEAD) {
   boolean isDead = true;
   for (int i = 0; i < this.particles.length; i++) {
    if (this.particles[i].isAlive()) {
     this.particles[i].update(container);
//     this.particles[i].update();
     isDead = false;
    }
   }
   if (isDead)
    this.state = STATE_DEAD;
  }
 }

 public void draw(Canvas canvas) {
  for(int i = 0; i < this.particles.length; i++) {
   if (this.particles[i].isAlive()) {
    this.particles[i].draw(canvas);
   }
  }
 }
}
[代碼]Particle.java

[java]
package net.obviam.particles.model; 
 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Rect; 
 
public class Particle { 
     
    public static final int STATE_ALIVE = 0;    // particle is alive  
    public static final int STATE_DEAD = 1;     // particle is dead  
     
    public static final int DEFAULT_LIFETIME    = 200;  // play with this  
    public static final int MAX_DIMENSION       = 5;    // the maximum width or height  
    public static final int MAX_SPEED           = 10;   // maximum speed (per update)  
     
    private int state;          // particle is alive or dead  
    private float widht;        // width of the particle  
    private float height;       // height of the particle  
    private float x, y;         // horizontal and vertical position  
    private double xv, yv;      // vertical and horizontal velocity  
    private int age;            // current age of the particle  
    private int lifetime;       // particle dies when it reaches this value  
    private int color;          // the color of the particle  
    private Paint paint;        // internal use to avoid instantiation  
     
     
    public int getState() { 
        return state; 
    } 
 
    public void setState(int state) { 
        this.state = state; 
    } 
 
    public float getWidht() { 
        return widht; 
    } 
 
    public void setWidht(float widht) { 
        this.widht = widht; 
    } 
 
    public float getHeight() { 
        return height; 
    } 
 
    public void setHeight(float height) { 
        this.height = height; 
    } 
 
    public float getX() { 
        return x; 
    } 
 
    public void setX(float x) { 
        this.x = x; 
    } 
 
    public float getY() { 
        return y; 
    } 
 
    public void setY(float y) { 
        this.y = y; 
    } 
 
    public double getXv() { 
        return xv; 
    } 
 
    public void setXv(double xv) { 
        this.xv = xv; 
    } 
 
    public double getYv() { 
        return yv; 
    } 
 
    public void setYv(double yv) { 
        this.yv = yv; 
    } 
 
    public int getAge() { 
        return age; 
    } 
 
    public void setAge(int age) { 
        this.age = age; 
    } 
 
    public int getLifetime() { 
        return lifetime; 
    } 
 
    public void setLifetime(int lifetime) { 
        this.lifetime = lifetime; 
    } 
 
    public int getColor() { 
        return color; 
    } 
 
    public void setColor(int color) { 
        this.color = color; 
    } 
     
    // helper methods -------------------------  
    public boolean isAlive() { 
        return this.state == STATE_ALIVE; 
    } 
    public boolean isDead() { 
        return this.state == STATE_DEAD; 
    } 
 
    public Particle(int x, int y) { 
        this.x = x; 
        this.y = y; 
        this.state = Particle.STATE_ALIVE; 
        this.widht = rndInt(1, MAX_DIMENSION); 
        this.height = this.widht; 
//      this.height = rnd(1, MAX_DIMENSION);  
        this.lifetime = DEFAULT_LIFETIME; 
        this.age = 0; 
        this.xv = (rndDbl(0, MAX_SPEED * 2) - MAX_SPEED); 
        this.yv = (rndDbl(0, MAX_SPEED * 2) - MAX_SPEED); 
        // smoothing out the diagonal speed  
        if (xv * xv + yv * yv > MAX_SPEED * MAX_SPEED) { 
            xv *= 0.7; 
            yv *= 0.7; 
        } 
        this.color = Color.argb(255, rndInt(0, 255), rndInt(0, 255), rndInt(0, 255)); 
        this.paint = new Paint(this.color); 
    } 
     
    /**
     * Resets the particle
     * @param x
     * @param y
     */ 
    public void reset(float x, float y) { 
        this.state = Particle.STATE_ALIVE; 
        this.x = x; 
        this.y = y; 
        this.age = 0; 
    } 
 
    // Return an integer that ranges from min inclusive to max inclusive.  
    static int rndInt(int min, int max) { 
        return (int) (min + Math.random() * (max - min + 1)); 
    } 
 
    static double rndDbl(double min, double max) { 
        return min + (max - min) * Math.random(); 
    } 
     
    public void update() { 
        if (this.state != STATE_DEAD) { 
            this.x += this.xv; 
            this.y += this.yv; 
             
            // extract alpha  
            int a = this.color >>> 24; 
            a -= 2;                             // fade by 5  
            if (a <= 0) {                        // if reached transparency kill the particle  
                this.state = STATE_DEAD; 
            } else { 
                this.color = (this.color & 0x00ffffff) + (a << 24);       // set the new alpha  
                this.paint.setAlpha(a); 
                this.age++;                     // increase the age of the particle  
//              this.widht *= 1.05;  
//              this.height *= 1.05;  
            } 
            if (this.age >= this.lifetime) { // reached the end if its life  
                this.state = STATE_DEAD; 
            } 
             
            // http://lab.polygonal.de/2007/05/10/bitwise-gems-fast-integer-math/  
            //32bit  
//          var color:uint = 0xff336699;  
//          var a:uint = color >>> 24;  
//          var r:uint = color >>> 16 & 0xFF;  
//          var g:uint = color >>>  8 & 0xFF;  
//          var b:uint = color & 0xFF;  
             
        } 
    } 
     
    public void update(Rect container) { 
        // update with collision  
        if (this.isAlive()) { 
            if (this.x <= container.left || this.x >= container.right - this.widht) { 
                this.xv *= -1; 
            } 
            // Bottom is 480 and top is 0 !!!  
            if (this.y <= container.top || this.y >= container.bottom - this.height) { 
                this.yv *= -1; 
            } 
        } 
        update(); 
    } 
 
    public void draw(Canvas canvas) { 
//      paint.setARGB(255, 128, 255, 50);  
        paint.setColor(this.color); 
        canvas.drawRect(this.x, this.y, this.x + this.widht, this.y + this.height, paint); 
//      canvas.drawCircle(x, y, widht, paint);  
    }