java - 需要加速 GOval 对象的帮助(制作 Breakout 游戏)

Question

大家好，我已经学习 Java 几周了，并决定制作我自己的 Breakout 版本。除了根据 Racket (GRect) 的速度修改球 (GOval) 速度的方法之外，游戏运行良好。不管怎样，方法是这样的:

private double paddleVelocity(){
            double paddleTracker=(paddleXTracker+paddleXTrackerTwo+paddleXTrackerThree)/3; //get the average x-coordinate for the paddle
            if(loopCounter>3){ //if the game has been through the loop more than three times (to ensure three x-coordinates have been stored)
                paddleVelocity=(paddle.getX()-paddleTracker)/50; //set paddleVelocity to the current paddle x-coordinate minus the average of the previous three paddle x-coordinates (which therefore finds the velocity and direction)
            }else{
                paddleVelocity=(paddle.getX()-paddleXTracker)/50; //takes the previous paddle x-coordinate and subtracts it from the current x-coordinate (which therefore finds the velocity and direction)
            }

            return (paddleVelocity);
        }

这是调用它的方法:

            private void detectCollisionPaddle(){;
                double ballY = ball.getY()+(BALL_RADIUS*2);
                if(paddle.getY()<=ballY && ball.getX()+BALL_RADIUS>=paddle.getX() && ball.getX()+BALL_RADIUS/2<=(paddle.getX()+PADDLE_WIDTH)){ //a mess of code which ensures the ball is within the bounds of the paddle
                    yVel=-yVel; //make the ball bounce off
                    bounceClip.play(); //play the bounce clip
                    xVel=xVel+paddleVelocity(); //increase the velocity of the ball in the direction and speed of the paddle
} }

实例变量包括:

private int loopCounter; //how many loops of the game code have been executed
private double paddleVelocity; //velocity of the paddle
private double paddleXTracker = 1; //value of the x-coordinate of the paddle one loop previous
private double paddleXTrackerTwo; //value of the x-coordinate of the paddle two loops previous
private double paddleXTrackerThree; //value of the x-coordinate of the paddle three loops previous
private double yVel = -1; //y velocity of the ball
private double xVel = 1; //x velocity of the ball

基本上，我希望 paddleVelocity 抓取桨的三个连续 x 坐标，并将它们与当前位置进行比较 (paddle.getX())。这使我能够确定用户移动桨的速度和方向。然后我返回结果(paddleVelocity)，该结果应该添加到球的当前速度(xVel)中。但是，这似乎无法正常运行。当删除对 paddleVelocity() 的调用时，代码可以完美运行(尽管没有加速)。所以我知道 paddleVelocity 方法存在问题。看来是偏右了。也许你们可以帮忙，毕竟这是我第一次认真尝试编程。这是游戏atm:http://cyb3rglitch.com/games/Glitchout_0.1/

是的，砖 block 还没有碎。 :P 干杯!

编辑:为了方便起见，以下是所有困惑的代码:

/*
 * File: Breakout.java
 * -------------------
 * Name: Vito Cassisi
 */

import acm.graphics.*;
import acm.program.*;
import acm.util.*;

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Breakout extends GraphicsProgram {

/** Width and height of application window in pixels */
    public static final int APPLICATION_WIDTH = 400;
    public static final int APPLICATION_HEIGHT = 600;

/** Dimensions of game board (usually the same) */
    private static final int WIDTH = APPLICATION_WIDTH;
    private static final int HEIGHT = APPLICATION_HEIGHT;

/** Dimensions of the paddle */
    private static final int PADDLE_WIDTH = 60;
    private static final int PADDLE_HEIGHT = 10;

/** Offset of the paddle up from the bottom */
    private static final int PADDLE_Y_OFFSET = 30;

/** Number of bricks per row */
    private static final int NBRICKS_PER_ROW = 10;

/** Number of rows of bricks */
    private static final int NBRICK_ROWS = 10;

/** Separation between bricks */
    private static final int BRICK_SEP = 4;

/** Width of a brick */
    private static final int BRICK_WIDTH =
      (WIDTH - (NBRICKS_PER_ROW - 1) * BRICK_SEP) / NBRICKS_PER_ROW;

/** Height of a brick */
    private static final int BRICK_HEIGHT = 8;

/** Radius of the ball in pixels */
    private static final int BALL_RADIUS = 10;

/**Ball speed in milliseonds*/
    private static final int DELAY = 10;

/** Offset of the top brick row from the top */
    private static final int BRICK_Y_OFFSET = 70;

/** Number of turns */
    private static final int NTURNS = 3;

    private static final int COUNTDOWN = 200;

    private GOval ball;
    private GRect paddle;
    private GRect block;
    private GLabel life;
    private GLabel countDown;
    private GObject getObject;
    AudioClip bounceClip = MediaTools.loadAudioClip("bounce.au");

/* Method: run() */
/** Runs the Breakout program. */
    public void run() {
        drawBlocks();
        drawPaddle();
        drawBall();
        drawLife();
        addMouseListeners();

        while(!lose) {
            detectCollisionWall();
            detectCollisionBlock();
            detectCollisionPaddle();
            decelerate();
            assignPaddleTrackers();
            pause(DELAY);
            loopCounter++;
        }
        GLabel youLose = new GLabel("You lose!",APPLICATION_WIDTH/2,APPLICATION_HEIGHT/2);
        youLose.setLocation((getWidth()-youLose.getWidth())/2, (getHeight()-youLose.getAscent())/2);
        add(youLose);
    }   
        private void drawBlocks(){
        /**Draw as many rows as defined in the constant 'NBRICKS_PER_ROW'*/ 
            for(int i = 0;i<NBRICK_ROWS;i++){
                blockX=(APPLICATION_WIDTH-((BRICK_WIDTH+BRICK_SEP)*NBRICKS_PER_ROW))/2; //center the blocks horizontally
                drawRow(); //draw the row
                blockY+=BRICK_HEIGHT+BRICK_SEP; //move the row down
            }
        }

        private void drawRow(){
        /**Draw as many bricks as defined in the constant 'NBRICKS_PER_ROW'*/   
            for(int i = 0;i<NBRICKS_PER_ROW;i++){
                block = new GRect(blockX,blockY,BRICK_WIDTH,BRICK_HEIGHT); //initialise the blocks
                add(block); //draw the blocks
                blockX+=BRICK_WIDTH+BRICK_SEP; //move x co-ordinate across
            }
        }

        private void drawPaddle(){
            paddle = new GRect((APPLICATION_WIDTH-PADDLE_WIDTH)/2,(APPLICATION_HEIGHT-PADDLE_Y_OFFSET-PADDLE_HEIGHT),PADDLE_WIDTH, PADDLE_HEIGHT);
            add(paddle);
        }

        private void drawBall(){
            double diameter = BALL_RADIUS*2;
            ball = new GOval((APPLICATION_WIDTH-diameter)/2,APPLICATION_HEIGHT-PADDLE_Y_OFFSET-PADDLE_HEIGHT*2-diameter,diameter,diameter);
            add(ball);
        }

        private void moveBall(){

            ball.move(xVel, yVel);
        }

        private void detectCollisionWall(){
            if(ball.getY()+(BALL_RADIUS*2)<getHeight() && ball.getY()>0 && ball.getX()+(BALL_RADIUS*2)<getWidth() && ball.getX()>0){
                moveBall();
            }
            if(ball.getY()+(BALL_RADIUS*2)>getHeight()){
                yVel=-yVel;
                turnsLeft--;
                testForLose();
                bounceClip.play();
            }
            if(ball.getY()<0){
                yVel=-yVel;
                bounceClip.play();
            }
            if(ball.getX()+(BALL_RADIUS*2)>=getWidth()){
                xVel=-xVel;
                bounceClip.play();
            }
            if(ball.getX()<=0){
                xVel=-xVel;
                bounceClip.play();
            }
            moveBall();
        }

        private void testForLose(){
            if(turnsLeft==0){
                lose=true;
                life.setLabel("You have "+turnsLeft+" lives!");
                return;
            }
            life.setLabel("You have "+turnsLeft+" lives!");
            remove(ball);
            drawBall();
            xVel=1;
            yVel=-1;
            drawCountDown();
        }

        private void drawCountDown(){
            GLabel countDown = new GLabel("",APPLICATION_WIDTH/2,APPLICATION_HEIGHT/2);
            for(int i=3;i>0;i--){
                countDown.setLabel("Respawn in: "+i);
                countDown.setLocation((getWidth()-countDown.getWidth())/2, (getHeight()-countDown.getAscent())/2);
                add(countDown);
                pause(COUNTDOWN);
            }
            countDown.setLabel("Go");
            countDown.setLocation((getWidth()-countDown.getWidth())/2, (getHeight()-countDown.getAscent())/2);
            pause(COUNTDOWN);
            remove(countDown);
        }

        private void drawLife(){
            life = new GLabel("You have "+turnsLeft+" lives!", APPLICATION_WIDTH/2,15);
            life.setLocation((getWidth()-life.getWidth())/2, 20);
            add(life);
        }

        private void detectCollisionBlock(){
            GObject collisionObject = detectObject(ball, BALL_RADIUS*2, BALL_RADIUS*2);
            if(collisionObject==block){
                remove(collisionObject);
                yVel=-yVel;
            }
        }

        private double paddleVelocity(){
            double paddleTracker=(paddleXTracker+paddleXTrackerTwo+paddleXTrackerThree)/3;
            if(loopCounter>3){
                paddleVelocity=(paddle.getX()-paddleTracker)/50;
                //paddleXTracker=paddle.getX();
            }else{
                paddleVelocity=(paddle.getX()-paddleXTracker)/50;
            }

            return (paddleVelocity);
        }

        private void detectCollisionPaddle(){;
            double ballY = ball.getY()+(BALL_RADIUS*2);
            //double ballX = ball.getX()+(BALL_RADIUS*2);
            /*if(ball.getY()+BALL_RADIUS*2>=paddle.getY() && ball.getX()+BALL_RADIUS*2>=paddle.getX() && ball.getX()<=paddle.getX()){
                ball.setLocation(ball.getX(),paddle.getY()-BALL_RADIUS*2-1);
            }*/
            if(paddle.getY()<=ballY && ball.getX()+BALL_RADIUS>=paddle.getX() && ball.getX()+BALL_RADIUS/2<=(paddle.getX()+PADDLE_WIDTH)){
                yVel=-yVel;
                bounceClip.play();
                xVel=xVel+paddleVelocity();
            /*
            int x = 4;
            int center = PADDLE_WIDTH/2;
            double parts=center/x;
            int location=0;
            if(ball.getX()+BALL_RADIUS*2>paddle.getX()&& ball.getX()<paddle.getX()+PADDLE_WIDTH){
            for(int i = 0;i<x;i++){
                if (ball.getX()<center+paddle.getX() && ball.getX()>(parts*i)+paddle.getX()){

                }else{
                    location = i;
                    break;  
                }

            }
            xVel=x/location;
            }
            }
            //

            if(ball.getX()+BALL_RADIUS<paddle.getX()+PADDLE_WIDTH/4){
                if(xVel!=1){
                    if(xVel<0)
                    {
                        xVel=xVel-1;
                    }else{
                        xVel=-xVel-1;
                    }
                }
            }
            if (ball.getX()>paddle.getX()+(PADDLE_WIDTH-PADDLE_WIDTH/4)){
                if(xVel>0){
                    xVel=xVel+1;
                }else{
                    xVel=-xVel+1;
                }
            }
            if (ball.getX()<paddle.getX()+(PADDLE_WIDTH-PADDLE_WIDTH/4) && ball.getX()+BALL_RADIUS>paddle.getX()+PADDLE_WIDTH/4){
                if(xVel>1){
                    xVel=xVel-1;
                }
                if(xVel<-1){
                    xVel=xVel+1;
                }
            }
            */
            }


        }

        public void mouseMoved(MouseEvent e){
            paddle.move((e.getX()-paddle.getX()-PADDLE_WIDTH/2),0);
        }

        /*Passes in an object to be checked, i.e. the ball, and asks for it's height and width. It returns the object if one is present, otherwise it retuns null.**/
        private GObject detectObject(GObject object, int width, int height){
            double right = object.getX()+width;
            double bottom = object.getY()+height;
            getObject = getElementAt(object.getX(),object.getY());

            if(getObject==null){
                getObject = getElementAt(right,object.getY());
            }else{
                return getObject;
            }

            if(getObject==null){
                getObject = getElementAt(object.getX(),bottom);
            }else{
                return getObject;
            }

            if(getObject==null){
                getObject = getElementAt(right,bottom);
            }else{
                return getObject;
            }

            if(getObject==null){
            return null;
            }else{
                return getObject;
            }

        }

        private void decelerate(){
            if(xVel<-1){
                xVel=xVel+0.01;
            }
            if(xVel>1){
                xVel=xVel-0.01;
            }
        }

        private void assignPaddleTrackers(){
            paddleXTrackerThree=paddleXTrackerTwo;
            paddleXTrackerTwo=paddleXTrackerThree;
            paddleXTracker=paddle.getX();
        }

    private int loopCounter;
    private double paddleVelocity;
    private double paddleXTracker = 1;
    private double paddleXTrackerTwo;
    private double paddleXTrackerThree;
    private double yVel = -1;
    private double xVel = 1;
    private int turnsLeft = NTURNS;
    private int blockY = BRICK_Y_OFFSET;
    private int blockX = 0;
    private static boolean lose = false;
    private RandomGenerator rgen = RandomGenerator.getInstance();

}

Answer 1

当桨速度更新时，我看不到您在哪里设置 paddleXTracker 和 friend 。所以这里有一些可能的修复:

1. 您不会连续更新过去的值，仅在开始时更新一次。
2. 您从未更新过 paddleXTrackerTwo 和 paddleXTrackerThree 值，因此如果原点位于左侧(可能)，则平均值位于左侧(由于除以 3)。

这两者都可以解释您所看到的正确偏见。

此外，您似乎正在执行 moving average 的临时版本。 。还有其他变体可能更适合您想要做的事情。

编辑

既然您的完整代码可用，我看不出有什么问题。我只能建议您采用调试技术，例如在游戏运行时打印 paddle*Tracker* 来查看输出的值以及它们是否符合预期。

编辑2

只是为了让这个答案成为一个答案，根据我们的 OOB 讨论，您的分配跟踪器函数是错误的，并且没有使用 paddleXTracker 更新 paddleXTrackerTwo。