bullet.java

还记得儿时在游戏机上玩坦克大战吗？如今这种经典游戏不在游戏机上玩了

                dy = 0;
                break;
        }
    }
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 15JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Set the bullet's strength.
     * @param strength the bullet's hitting strength.
     */
    public void setStrength(int strength){
        this.strength=strength;
    }
    
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 15JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * the bullet hit something and explodes
     */
    public void explode() {
        setVisible(false);
        Explosion.explode(getRefPixelX(), getRefPixelY(), Explosion.SMALL);
    }

    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 15JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Operation be done in each tick.
     */
    public void tick(){
        if (!isVisible() || direction==BattleField.NONE)
            return;
        // Move the bullet.
        move(dx, dy);
        int x = getRefPixelX();
        int y = getRefPixelY();
        PlayerTank playerTank=(PlayerTank)Tank.getTank(0);
        //outside the battle field, hitting the border
        if (x <= 0 || x >= battleField.getWidth() || y <= 0
                || y >= battleField.getHeight()) {

            //this is to avoid explosition outside the battlefield.
            if(x<=0) x=0;
            if(x >= battleField.getWidth()) x= battleField.getWidth();
            if(y<=0) y=0;
            if(y>= battleField.getHeight())y=battleField.getHeight();
            setPosition(x,y);
            explode();
            return;
        }
        
        // See if it hit a tank.
        if (friendly) {
            // See if it hit an enemy tank.
            for (int i = 1; i < Tank.POOL_SIZE; i++) {
                EnemyTank enemy = (EnemyTank)Tank.getTank(i);
                if (enemy!=null && enemy.isVisible() && 
                        collidesWith(enemy, false)) {
                    enemy.explode();
                    explode();
                    return;
                }
            }
        } else {
            // See if it hit player tank.
            
            if (collidesWith(playerTank, false)) {
                playerTank.explode();
                explode();
                return;
            }
        }
        
        //check to see if hit player's home
        if(Powerup.isHittingHome(this)){
            //TODO: Game Over
            explode();
            return; 
        }
        // See if it hit a wall.
        if (battleField.hitWall(x, y, strength)) {
            explode();
            return;
        }
        
        // See if it hit another bullet.
        for (int i = 0; i < POOL_SIZE; i++) {
            Bullet anotherBullet=BULLET_POOL[i];
            if(this!=anotherBullet && anotherBullet.isVisible()){
                if (collidesWith(anotherBullet, false)) {
                    explode();
                    BULLET_POOL[i].explode();
                    return;
                }
            }
        }
    }
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 15JAN2008  James Shen                 	          Initial Creation
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Set the layerManager for tanks.
     */
    public static void setLayerManager(LayerManager manager) {
        layerManager = manager;
        if (layerManager != null){
            for (int i = 0; i < POOL_SIZE; i++)
                layerManager.append(BULLET_POOL[i]);
        }
    }
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 15JAN2008  James Shen                 	          Initial Creation
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Set the Battle field for tanks.
     */
    public static void setBattleField(BattleField field) {
        battleField = field;
    }
    
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 17JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Get how many bullets the player shot.the player can shoot 3 bullets 
     * at most.
     */
    public static int getPlayerBulletCount(){
        int count=0;
        for(int i=0;i<POOL_SIZE;i++){
            if(BULLET_POOL[i].isVisible() && BULLET_POOL[i].friendly ){
                count++;
            }
        }
        return count;
    }
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 17JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Get a free bullet from the pool.
     */
    public static Bullet getFreeBullet(){
        for(int i=0;i<POOL_SIZE;i++){
            if(!BULLET_POOL[i].isVisible()){
                BULLET_POOL[i].setVisible(true);
                return  BULLET_POOL[i];
            }
        }
        return null;
    }
    
    ////////////////////////////////////////////////////////////////////////////
    //--------------------------------- REVISIONS ------------------------------
    // Date       Name                 Tracking #         Description
    // ---------  -------------------  -------------      ----------------------
    // 17JAN2008  James Shen                 	          Initial Creation 
    ////////////////////////////////////////////////////////////////////////////
    /**
     * Stop all bullets in the game scene.
     */
    public static void stopAllBullets() {
        for (int i = 0; i < POOL_SIZE; ++i)
        {
            if(!BULLET_POOL[i].friendly){
                BULLET_POOL[i].setVisible(false);
            }
        }
        
    }
   
}