如何调用一个函数并通过按一次键使其继续

Question

我希望在按下空格键一次后，下面代码中的ball.move();函数继续运行。只有当我继续按空格键时，它才起作用。

void draw() {
if (start == true) {ball.move();}
}

void keyPressed() {
if (key == ' '){start = true;}    
}
void keyReleased() {
if (key == ' ') {start = false;}
} 

这是我正在制作的一款乒乓球游戏，每次球击中边缘时，它都会被传送到画布的中心。那是我希望能够再次手动开始球的移动的时候。

这是整个代码：

Ball ball;
Player player1;
Player player2;
int scorePlayer1 = 0;
int scorePlayer2 = 0;
PFont font;
boolean start;
void setup() {
size(1368,768);
frameRate(144);
noStroke();
ball = new Ball(width/2, height/2, 30);
player1 = new Player(15, height/2, 30, 150);
player2 = new Player(width-15, height/2, 30, 150);
ball.speedX = 10;
}
void draw() {
background(0);
textSize(40);
textAlign(CENTER);
font = loadFont("Arial-Black-48.vlw");
textFont(font);
ball.display();
if (start == true) {ball.move();}
player1.run();
player2.run();
//Score 
if (ball.left() < 0) {
scorePlayer2 = scorePlayer2 + 1;
ball.x = width/2;
ball.y = height/2;
}
if (ball.right() > width) {
scorePlayer1 = scorePlayer1 +1;
ball.x = width/2;
ball.y = height/2;
}
text(scorePlayer1, width/2-75, 50);
text(scorePlayer2, width/2+75, 50);
//Collision
if (ball.top() < 0) {
ball.speedY = -ball.speedY;
}
if (ball.bottom() > height) {
ball.speedY = -ball.speedY;
}
if (ball.left() < player1.right() && ball.y > player1.top()-10 && ball.y < player1.bottom()+10) {
ball.speedX = -ball.speedX;
ball.speedY = map(ball.y - player1.y, -player1.h/2, player1.h/2, -5, 5);
}
if (ball.right() > player2.left() && ball.y > player2.top()-10 && ball.y < player2.bottom()+10) {
ball.speedX = -ball.speedX;
ball.speedY = map(ball.y - player2.y, -player2.h/2, player2.h/2, -5, 5);
}
if (player1.bottom() > height) {
player1.y = height-player1.h/2;  
}
if (player1.top() < 0) {
player1.y = player1.h/2;
}
if (player2.bottom() > height) {
player2.y = height-player1.h/2;  
}
if (player2.top() < 0) {
player2.y = player1.h/2;
}
}
//Movement
void keyPressed() {
player1.pressed((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.pressed((keyCode == UP), (keyCode == DOWN));   
if (key == ' '){start = true;}    
}
void keyReleased() {
player1.released((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.released((keyCode == UP), (keyCode == DOWN));
if (key == ' ') {start = false;}
}
class Ball {
float x;
float y;
float d;
float speedX;
float speedY;
color c;
//Constructor
Ball(float tempX, float tempY, float tempD){
x = tempX;
y = tempY;
d = tempD;
speedX = 0;
speedY = 0;
c = (255);
}
void display() {
fill(c);
ellipse(x,y,d,d);
}
void move() {
x = x + speedX;
y = y + speedY;
}
//Collision help
float top() {
return y-d/2;
}
float bottom() {
return y+d/2;
}
float left() {
return x-d/2;
}
float right() {
return x+d/2;
}
}
class Player {
float x, y;
float w, h;
float speedY = 0.0;
color c;
boolean moveUp = false, moveDown = false;
//Constructor
Player(float tempX, float tempY, float tempW, float tempH){
x = tempX;
y = tempY;
w = tempW;
h = tempH;
speedY = 0;
c = (255);
}
void run() {
display();
move();
}
void display() {
fill(c);
rect(x-w/2, y-h/2, w, h);
}
//Movement
void move() {
if (!moveUp && !moveDown) {speedY = speedY * 0.85;}
if (moveUp)               {speedY -= 1;} 
if (moveDown)             {speedY += 1;}
speedY = max(-7.0, min(7.0, speedY));
y += speedY;

}
void pressed(boolean up, boolean down) {
if (up) {moveUp = true;}
if (down) {moveDown = true;}
}
void released(boolean up, boolean down) {
if (up) {moveUp = false;}
if (down) {moveDown = false;}
}
//Collision help
float top() {
return y-h/2;
}
float bottom() {
return y+h/2;
}
float left() {
return x-w/2;
}
float right() {
return x+w/2;
}

}

Answer 1

在下面的代码中，当按键时将start设置为true，当按键完成时将其设置为false。当按键完成时，你可以简单地删除将start设置为false的线，并且当空格被按下时，球总是会移动。

//Movement
void keyPressed() {
player1.pressed((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.pressed((keyCode == UP), (keyCode == DOWN));   
if (key == ' '){start = true;}    
}
void keyReleased() {
player1.released((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.released((keyCode == UP), (keyCode == DOWN));
//if (key == ' ') {start = false;}
}

我想你希望球在空间再次被挤压时停止移动。这也可以在keyPressed方法中通过切换start而不是将其设置为true来完成。类似if (key == ' '){start = !start;}

Answer 2

您的问题是，当您释放空格键时，它会将start字段设置为false。然后，当调用下一个draw()方法时，它会看到start==false因此不会移动球。

如果从keyReleased方法中删除该行，那么它应该正确运行吗？