Question

我创建了一个产生球的程序，可以通过单击并拖动鼠标来抛出。我决定添加一个功能，可以通过单击按钮添加墙。然后墙壁将移动到鼠标的位置。

void setup() {
  size(640,360);
  background(50);
}

  // Speed of ball
 float xSpeed = 5;
 float ySpeed = 1;
 // Ball size
 float circleRad = 12;
 // Ball position
 float circleX = 0 + circleRad;
 float circleY = 180;
 // Ball physics
 float gravity = 0.35;
 float friction = 0.075;
 // Wall position
 float wallX = 320;
 float wallY = 180;
 // Wall dimensions
 float wallWidth = 20;
 float wallHeight = height;
 // Determines whether or not the wall's position is currently being changed
 boolean wall = false;

void draw() {
  background(50);
  noStroke();  

  fill(85);
  rect(25,25,50,50);

  ellipseMode(RADIUS);
  rectMode(CENTER);
  // If button is pressed, wall is being created/moved
  if(mousePressed && mouseX <= 50 && mouseY <= 50) {
    wall = true;
  }
  // If mouse is pressed and wall isnt being created/moved, move circle to mouse's position
  if (mousePressed && wall == false) {
    circleX = mouseX;
    circleY = mouseY;
  }

  // Creates/moves wall
  if(wall == true){
    wallX = mouseX;
    fill(170);
    rect(wallX, wallY, wallWidth, wallHeight);
  }

  // Creates ball
  fill(255);
  ellipse(circleX,circleY,circleRad,circleRad);

  // Bounces ball off of walls/ceiling/floor, implements ball physics
  if (!mousePressed){
    circleX+=xSpeed;
    circleY+=ySpeed;

    if(circleX >= width - circleRad) {
      xSpeed *= -1;
      circleX = width - circleRad;
    }

    if (circleX <= 0 + circleRad) {
      xSpeed *= -1;
      circleX = 0 + circleRad;
    }

    if (circleY >= height - circleRad) {
      ySpeed *= -1;
      ySpeed += 0.9;
      circleY = height - circleRad;
    }

    if (circleY <= 0 + circleRad) {
      ySpeed *= -1;
      circleY = 0 + circleRad;
    }

    if((circleY <= 0 + circleRad || circleY >= height - circleRad) && xSpeed >= 0) {
      xSpeed -= friction;
    }
    if((circleY <= 0 + circleRad || circleY >= height - circleRad) && xSpeed <= 0){
      xSpeed -= friction * -1;
    }

    if(xSpeed >= -0.1 && xSpeed <= 0.1) {
      xSpeed = 0;
    }

    if(xSpeed <= 0){
      xSpeed -= friction * -0.1;
    }

    if(xSpeed >= 0){
      xSpeed -= friction * 0.1;
    }
    ySpeed += gravity;
    }
}

// Sets ball speed to speed of mouse once mouse is released, allowing for throwing of ball
void mouseReleased(){
   xSpeed = mouseX - pmouseX;
   ySpeed = mouseY - pmouseY;
}

我还没有完成这个功能，（球还没有从墙上反弹，也没有办法阻止墙跟着鼠标）但我遇到了一个问题。每当我点击按钮创建墙壁时，程序就会看到我已经释放了鼠标，并决定扔球。通常有人在点击时不会移动鼠标，因此结果是球的速度设置为0.我试图通过在mouse语句中包含mouseReleased（）函数内部的代码来解决这个问题： / p>

void mouseReleased(){
   if(wall == false){
     xSpeed = mouseX - pmouseX;
     ySpeed = mouseY - pmouseY;
  }
}

但这会导致另一个问题;当按下鼠标时，球在空中暂停，并在释放鼠标时恢复。我怎样才能按下按钮，墙壁开始建造，球完全不受影响？

Answer 1

你拥有在if声明中移动球的所有逻辑：

if (!mousePressed){

因此，只有在未按下鼠标时，您的球才会移动。换句话说，当您按下鼠标时，球会停止移动。

快速而愚蠢的解决方法是为此if语句添加一些逻辑。想想你何时想要移动球：当没有按下鼠标，或者按下鼠标但是你正在移动墙壁时，对吗？这看起来像这样：

if (!mousePressed || wall){

但更一般地说，您可能想退一步并清理一下代码。查看您在mousePressed语句中检查wall和if的次数。您可能应该尝试重构，以便您的逻辑更容易阅读。这将有助于您思考代码正在做什么，这将使您的生活更轻松。

运行mouseReleased（）仅在某些条件下运行

1 个答案: