asteroids.java

来自「很有趣的射击游戏」· Java 代码 · 共 1,251 行 · 第 1/3 页

      loaded = true;
      loadThread.stop();
    }

    // This is the main loop.

    while (Thread.currentThread() == loopThread) {

      if (!paused) {

        // Move and process all sprites.

        updateShip();
        updatePhotons();
        updateUfo();
        updateMissle();
        updateAsteroids();
        updateExplosions();

        // Check the score and advance high score, add a new ship or start the flying
        // saucer as necessary.

        if (score > highScore)
          highScore = score;
        if (score > newShipScore) {
          newShipScore += NEW_SHIP_POINTS;
          shipsLeft++;
        }
        if (playing && score > newUfoScore && !ufo.active) {
          newUfoScore += NEW_UFO_POINTS;
          ufoPassesLeft = UFO_PASSES;
          initUfo();
        }

        // If all asteroids have been destroyed create a new batch.

        if (asteroidsLeft <= 0)
            if (--asteroidsCounter <= 0)
              initAsteroids();
      }

      // Update the screen and set the timer for the next loop.

      repaint();
      try {
        startTime += DELAY;
        Thread.sleep(Math.max(0, startTime - System.currentTimeMillis()));
      }
      catch (InterruptedException e) {
        break;
      }
    }
  }

  public void loadSounds() {

    // Load all sound clips by playing and immediately stopping them.

    try {
      crashSound     = getAudioClip(new URL(getDocumentBase(), "crash.au"));
      explosionSound = getAudioClip(new URL(getDocumentBase(), "explosion.au"));
      fireSound      = getAudioClip(new URL(getDocumentBase(), "fire.au"));
      missleSound    = getAudioClip(new URL(getDocumentBase(), "missle.au"));
      saucerSound    = getAudioClip(new URL(getDocumentBase(), "saucer.au"));
      thrustersSound = getAudioClip(new URL(getDocumentBase(), "thrusters.au"));
      warpSound      = getAudioClip(new URL(getDocumentBase(), "warp.au"));
    }
    catch (MalformedURLException e) {}

    crashSound.play();     crashSound.stop();
    explosionSound.play(); explosionSound.stop();
    fireSound.play();      fireSound.stop();
    missleSound.play();    missleSound.stop();
    saucerSound.play();    saucerSound.stop();
    thrustersSound.play(); thrustersSound.stop();
    warpSound.play();      warpSound.stop();
  }

  public void initShip() {

    ship.active = true;
    ship.angle = 0.0;
    ship.deltaAngle = 0.0;
    ship.currentX = 0.0;
    ship.currentY = 0.0;
    ship.deltaX = 0.0;
    ship.deltaY = 0.0;
    ship.render();
    if (loaded)
      thrustersSound.stop();
    thrustersPlaying = false;

    hyperCounter = 0;
  }

  public void updateShip() {

    double dx, dy, limit;

    if (!playing)
      return;

    // Rotate the ship if left or right cursor key is down.

    if (left) {
      ship.angle += Math.PI / 16.0;
      if (ship.angle > 2 * Math.PI)
        ship.angle -= 2 * Math.PI;
    }
    if (right) {
      ship.angle -= Math.PI / 16.0;
      if (ship.angle < 0)
        ship.angle += 2 * Math.PI;
    }

    // Fire thrusters if up or down cursor key is down. Don't let ship go past
    // the speed limit.

    dx = -Math.sin(ship.angle);
    dy =  Math.cos(ship.angle);
    limit = 0.8 * MIN_ROCK_SIZE;
    if (up) {
      if (ship.deltaX + dx > -limit && ship.deltaX + dx < limit)
        ship.deltaX += dx;
      if (ship.deltaY + dy > -limit && ship.deltaY + dy < limit)
        ship.deltaY += dy;
    }
    if (down) {
      if (ship.deltaX - dx > -limit && ship.deltaX - dx < limit)
        ship.deltaX -= dx;
      if (ship.deltaY - dy > -limit && ship.deltaY - dy < limit)
        ship.deltaY -= dy;
    }

    // Move the ship. If it is currently in hyperspace, advance the countdown.

    if (ship.active) {
      ship.advance();
      ship.render();
      if (hyperCounter > 0)
        hyperCounter--;
    }

    // Ship is exploding, advance the countdown or create a new ship if it is
    // done exploding. The new ship is added as though it were in hyperspace.
    // (This gives the player time to move the ship if it is in imminent danger.)
    // If that was the last ship, end the game.

    else
      if (--shipCounter <= 0)
        if (shipsLeft > 0) {
          initShip();
          hyperCounter = HYPER_COUNT;
        }
        else
          endGame();
  }

  public void stopShip() {

    ship.active = false;
    shipCounter = SCRAP_COUNT;
    if (shipsLeft > 0)
      shipsLeft--;
    if (loaded)
      thrustersSound.stop();
    thrustersPlaying = false;
  }

  public void initPhotons() {

    int i;

    for (i = 0; i < MAX_SHOTS; i++) {
      photons[i].active = false;
      photonCounter[i] = 0;
    }
    photonIndex = 0;
  }

  public void updatePhotons() {

    int i;

    // Move any active photons. Stop it when its counter has expired.

    for (i = 0; i < MAX_SHOTS; i++)
      if (photons[i].active) {
        photons[i].advance();
        photons[i].render();
        if (--photonCounter[i] < 0)
          photons[i].active = false;
      }
  }

  public void initUfo() {

    double temp;

    // Randomly set flying saucer at left or right edge of the screen.

    ufo.active = true;
    ufo.currentX = -AsteroidsSprite.width / 2;
    ufo.currentY = Math.random() * AsteroidsSprite.height;
    ufo.deltaX = MIN_ROCK_SPEED + Math.random() * (MAX_ROCK_SPEED - MIN_ROCK_SPEED);
    if (Math.random() < 0.5) {
      ufo.deltaX = -ufo.deltaX;
      ufo.currentX = AsteroidsSprite.width / 2;
    }
    ufo.deltaY = MIN_ROCK_SPEED + Math.random() * (MAX_ROCK_SPEED - MIN_ROCK_SPEED);
    if (Math.random() < 0.5)
      ufo.deltaY = -ufo.deltaY;
    ufo.render();
    saucerPlaying = true;
    if (sound)
      saucerSound.loop();

    // Set counter for this pass.

    ufoCounter = (int) Math.floor(AsteroidsSprite.width / Math.abs(ufo.deltaX));
  }

  public void updateUfo() {

    int i, d;

    // Move the flying saucer and check for collision with a photon. Stop it when its
    // counter has expired.

    if (ufo.active) {
      ufo.advance();
      ufo.render();
      if (--ufoCounter <= 0)
        if (--ufoPassesLeft > 0)
          initUfo();
        else
          stopUfo();
      else {
        for (i = 0; i < MAX_SHOTS; i++)
          if (photons[i].active && ufo.isColliding(photons[i])) {
            if (sound)
              crashSound.play();
            explode(ufo);
            stopUfo();
            score += UFO_POINTS;
          }

          // On occassion, fire a missle at the ship if the saucer is not
          // too close to it.

          d = (int) Math.max(Math.abs(ufo.currentX - ship.currentX), Math.abs(ufo.currentY - ship.currentY));
          if (ship.active && hyperCounter <= 0 && ufo.active && !missle.active &&
              d > 4 * MAX_ROCK_SIZE && Math.random() < .03)
            initMissle();
       }
    }
  }

  public void stopUfo() {

    ufo.active = false;
    ufoCounter = 0;
    ufoPassesLeft = 0;
    if (loaded)
      saucerSound.stop();
    saucerPlaying = false;
  }

  public void initMissle() {

    missle.active = true;
    missle.angle = 0.0;
    missle.deltaAngle = 0.0;
    missle.currentX = ufo.currentX;
    missle.currentY = ufo.currentY;
    missle.deltaX = 0.0;
    missle.deltaY = 0.0;
    missle.render();
    missleCounter = 3 * Math.max(AsteroidsSprite.width, AsteroidsSprite.height) / MIN_ROCK_SIZE;
    if (sound)
      missleSound.loop();
    misslePlaying = true;
  }

  public void updateMissle() {

    int i;

    // Move the guided missle and check for collision with ship or photon. Stop it when its
    // counter has expired.

    if (missle.active) {
      if (--missleCounter <= 0)
        stopMissle();
      else {
        guideMissle();
        missle.advance();
        missle.render();
        for (i = 0; i < MAX_SHOTS; i++)
          if (photons[i].active && missle.isColliding(photons[i])) {
            if (sound)
              crashSound.play();
            explode(missle);
            stopMissle();
            score += MISSLE_POINTS;
          }
        if (missle.active && ship.active && hyperCounter <= 0 && ship.isColliding(missle)) {
          if (sound)
            crashSound.play();
          explode(ship);
          stopShip();
          stopUfo();
          stopMissle();
        }
      }
    }
  }

  public void guideMissle() {

    double dx, dy, angle;

    if (!ship.active || hyperCounter > 0)
      return;

    // Find the angle needed to hit the ship.

    dx = ship.currentX - missle.currentX;
    dy = ship.currentY - missle.currentY;
    if (dx == 0 && dy == 0)
      angle = 0;
    if (dx == 0) {
      if (dy < 0)
        angle = -Math.PI / 2;
      else
        angle = Math.PI / 2;
    }
    else {
      angle = Math.atan(Math.abs(dy / dx));
      if (dy > 0)
        angle = -angle;
      if (dx < 0)
        angle = Math.PI - angle;
    }

    // Adjust angle for screen coordinates.

    missle.angle = angle - Math.PI / 2;

    // Change the missle's angle so that it points toward the ship.

    missle.deltaX = MIN_ROCK_SIZE / 3 * -Math.sin(missle.angle);
    missle.deltaY = MIN_ROCK_SIZE / 3 *  Math.cos(missle.angle);
  }

  public void stopMissle() {

    missle.active = false;
    missleCounter = 0;
    if (loaded)
      missleSound.stop();
    misslePlaying = false;
  }

  public void initAsteroids() {

    int i, j;
    int s;
    double theta, r;
    int x, y;

    // Create random shapes, positions and movements for each asteroid.

    for (i = 0; i < MAX_ROCKS; i++) {

      // Create a jagged shape for the asteroid and give it a random rotation.

      asteroids[i].shape = new Polygon();
      s = MIN_ROCK_SIDES + (int) (Math.random() * (MAX_ROCK_SIDES - MIN_ROCK_SIDES));
      for (j = 0; j < s; j ++) {
        theta = 2 * Math.PI / s * j;
        r = MIN_ROCK_SIZE + (int) (Math.random() * (MAX_ROCK_SIZE - MIN_ROCK_SIZE));
        x = (int) -Math.round(r * Math.sin(theta));
        y = (int)  Math.round(r * Math.cos(theta));
        asteroids[i].shape.addPoint(x, y);
      }
      asteroids[i].active = true;
      asteroids[i].angle = 0.0;
      asteroids[i].deltaAngle = (Math.random() - 0.5) / 10;

      // Place the asteroid at one edge of the screen.

      if (Math.random() < 0.5) {
        asteroids[i].currentX = -AsteroidsSprite.width / 2;
        if (Math.random() < 0.5)
          asteroids[i].currentX = AsteroidsSprite.width / 2;
        asteroids[i].currentY = Math.random() * AsteroidsSprite.height;
      }
      else {
        asteroids[i].currentX = Math.random() * AsteroidsSprite.width;
        asteroids[i].currentY = -AsteroidsSprite.height / 2;
        if (Math.random() < 0.5)
          asteroids[i].currentY = AsteroidsSprite.height / 2;
      }

      // Set a random motion for the asteroid.

      asteroids[i].deltaX = Math.random() * asteroidsSpeed;
      if (Math.random() < 0.5)
        asteroids[i].deltaX = -asteroids[i].deltaX;
      asteroids[i].deltaY = Math.random() * asteroidsSpeed;
      if (Math.random() < 0.5)
        asteroids[i].deltaY = -asteroids[i].deltaY;

      asteroids[i].render();
      asteroidIsSmall[i] = false;
    }