【Java开源代码栏目提醒】:网学会员为广大网友收集整理了,Tumbleweed.java,希望对大家有所帮助!
package ch09;
import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
//该类负责绘制滚动的风滚草
public class Tumbleweed
extends Sprite {
//每副图片宽度为16,高度也为16
static int WIDTH = 16;
//用于获取一个代表风滚草再次出现时机的随机数
Random myRandom = new Random();
//代表是否被牛仔娃娃跳过
boolean myJumpedOver;
//声明一个代表左右方向的变量
boolean myLeft;
//声明一个代表绘制风滚草Y坐标的变量
int myY;
/*
39.风滚草Tumbleweed类的构造器
*/
public Tumbleweed(boolean left) throws Exception {
super(Image.createImage("/icons/cowboy/tumbleweed.png"),
WIDTH, WIDTH);
myY = JumpManager.DISP_HEIGHT - WIDTH - 2;
myLeft = left;
if (!myLeft) {
setTransform(TRANS_MIRROR);
}
myJumpedOver = false;
setVisible(false);
}
/*
40.重置风滚草对象状态,在层管理类JumpManager的reset()方法中被调用
*/
void reset() {
setVisible(false);
myJumpedOver = false;
}
/*
41.改变风滚草滚动状态,在层管理类JumpManager的advance()方法中被调用
*/
int advance(Cowboy cowboy, int tickCount, boolean left,
int currentLeftBound, int currentRightBound) {
int retVal = 0;
//判断风滚草是否超出屏幕,超出置为不可视
if ( (getRefPixelX() + WIDTH <= currentLeftBound) ||
(getRefPixelX() - WIDTH >= currentRightBound)) {
setVisible(false);
}
//重新使用不可视的风滚草
if (!isVisible()) { //该方法继承至Layer类
int rand = getRandomInt(100);
if (rand == 3) {
//重新使用,重置初始化状态
myJumpedOver = false;
setVisible(true);
if (myLeft) {
setRefPixelPosition(currentRightBound, myY);
move( -1, 0);
}
else {
setRefPixelPosition(currentLeftBound, myY);
move(1, 0);
}
}
}
//处理可视的风滚草
else {
//每隔2次绘制屏幕,刷新一次图像帧,
if (tickCount % 2 == 0) { //控制牛仔娃娃动作快慢
nextFrame();
}
//处理左边风滚草
if (myLeft) {
move( -3, 0);
//根据水平坐标判断得分
if ( (!myJumpedOver) &&
(getRefPixelX() < cowboy.getRefPixelX())) {
myJumpedOver = true;
retVal = cowboy.increaseScoreThisJump();
}
}
//处理右边风滚草
else {
move(3, 0);
//根据水平坐标判断得分
if ( (!myJumpedOver) &&
(getRefPixelX() > cowboy.getRefPixelX() + Cowboy.WIDTH)) {
myJumpedOver = true;
retVal = cowboy.increaseScoreThisJump();
}
}
}
return (retVal);
}
/*
42.生成一个代表风滚草再次出现时机的随机数
*/
public int getRandomInt(int upper) {
int retVal = myRandom.nextInt() % upper;
if (retVal < 0) {
retVal += upper;
}
return (retVal);
}
}