chasesprite.java

j2me手机游戏HighSeas2 这是用midp２．０ 在eclipse上开发的游戏源程序．供参考

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import java.util.*;

public class ChaseSprite extends Sprite {
  private Random     rand;
  private int        speed;
  private TiledLayer barrier;
  private boolean    directional;
  private Sprite     chasee;
  private int        aggression;  // 0 - 10

  public ChaseSprite(Image image, int frameWidth, int frameHeight, int chaseSpeed,
    TiledLayer barrierLayer, boolean hasDirection, Sprite chaseeSprite,
    int aggressionLevel) {
    super(image, frameWidth, frameHeight);

    // Initialize the random number generator
    rand = new Random();

    // Set the speed
    speed = chaseSpeed;

    // Set the tiled layer barrier
    barrier = barrierLayer;

    // Set whether or not the sprite is directional
    directional = hasDirection;

    // Set the chasee sprite
    chasee = chaseeSprite;

    // Set the aggression level
    aggression = aggressionLevel;
  }

  public void update() {
    // Temporarily save the position
    int xPos = getX();
    int yPos = getY();
    int direction = 0;  // up = 0, right = 1, down = 2, left = 3

    // Chase or move randomly based on the aggression level
    if (Math.abs(rand.nextInt() % (aggression + 1)) > 0) {
      // Chase the chasee
      if (getX() > (chasee.getX() + chasee.getWidth() / 2)) {
        // Chase left
        move(-speed, 0);
        direction = 3;
      }
      else if ((getX() + getWidth() / 2) < chasee.getX()) {
        // Chase right
        move(speed, 0);
        direction = 1;
      }
      if (getY() > (chasee.getY() + chasee.getHeight() / 2)) {
        // Chase up
        move(0, -speed);
        direction = 0;
      }
      else if ((getY() + getHeight() / 2) < chasee.getY()) {
        // Chase down
        move(0, speed);
        direction = 2;
      }
    }
    else {
      // Move in a random direction
      switch (Math.abs(rand.nextInt() % 4)) {
      // Move left
      case 0:
        move(-speed, 0);
        direction = 3;
        break;
      // Move right
      case 1:
        move(speed, 0);
        direction = 1;
        break;
      // Move up
      case 2:
        move(0, -speed);
        direction = 0;
        break;
      // Move down
      case 3:
        move(0, speed);
        direction = 2;
        break;
      }
    }

    // Check for a collision with the barrier
    if (barrier != null && collidesWith(barrier, true)) {
      // Move the sprite back to its original position
      setPosition(xPos, yPos);
    }

    // Move to the next animation frame based on directional or not
    if (directional)
      setFrame(direction);
    else
      nextFrame();
  }
}