使用按键移动物体并拍摄小方块

Question

在我的按键部分，我不太确定我需要做什么才能让方块上下移动。目前速度非常慢。我也想弄清楚如何从大广场拍摄迷你广场；

boolean updown = false;
int squareX = 20;
int squareY = 20;
int speed = 30;
int circleX = 150;

void setup () {
  size (700,700);
}

void draw () {
  background (0);

  fill(100);
  ellipse (circleX,140,150,150);
  circleX -=2;
  if (circleX < - 20) {
    circleX = 550;
  }

  fill (225);
  rect (squareX, squareY, 70, 70);
  if (updown) squareY = squareY + speed;
  
   if (squareY>width || squareY <0) {
     speed=speed*-1;

   }
}

Answer 1

目前，您直接将 squareY 增加 1 个像素。 理想情况下，您只需在想要移动方块时将其设置为 > 0 的值来控制速度，或者在您想要停止移动时将其重置为 0。

还有一些其他的东西可以让它变得更好，例如：

• 在检查方块是否在屏幕区域之外时使用方块的大小
• 记住正方形离开屏幕之前最后一个好的 y 位置，以便在翻转位置时重置位置。

这是您的草图的修改版本，其中包含上述注释以及以保持相关元素分组的方式命名变量：

int squarePositionX = 20;
int squarePositionY = 20;
int squareVelocityY = 0;
int squareLastGoodY = squarePositionY;
int squareSize = 70;
int squareSpeed = 9;

int circleX = 150;

void setup () {
  size (700, 700);
}

void draw () {
  // handle keys
  if(keyPressed){
    if(key == 'w'){
      squareVelocityY = -squareSpeed;
    }
    if(key == 's'){
      squareVelocityY =  squareSpeed;
    }
  }else{
    // reset velocity (stop square from moving)
    squareVelocityY = 0;
  }
  
  // update big square position based on velocity
  squarePositionY += squareVelocityY;
  // check if square is still on screen (reset velocity if it's not otherwise keep track of it's last 
  if (squarePositionY >= width - squareSize || squarePositionY <= 0) {
    // flip Y velocity
    squareVelocityY *= -1;
    // reset to last good known Y position
    squarePositionY = squareLastGoodY;
  }else{
    squareLastGoodY = squarePositionY;
  }
  
  // clear screen
  background (0);

  // render big square
  fill (225);
  rect (squarePositionX, squarePositionY, squareSize, squareSize);
  
  // render circle
  fill(100);
  ellipse (circleX, 140, 150, 150);
  // update circle position
  circleX -= 2;
  if (circleX < - 20) {
    circleX = 550;
  }
}

希望 cmets 帮助更详细地解释发生了什么。

关于拍摄迷你方块，您需要跟踪每个迷你方块的位置。您可以使用数组和append() 在新子弹射击时扩展它，或者只使用具有动态大小的数组类型，例如ArrayList 或IntList。为了保持列表有效且不被屏幕区域之外的项目符号淹没，您可以对大方块进行类似的测试，以检查小方块何时从列表中移除。剩下要做的最后一件事就是简单地渲染小方块，只要它们可见。

这是一个注释草图来说明这个想法：

int squareSize = 70;
int squarePositionX = squareSize;
int squarePositionY = squareSize;
int squareVelocityY = 0;
int squareLastGoodY = squarePositionY;
int squareSpeed = 3;

int circleX = 150;

// store positions for 
IntList miniSquarePositionsX = new IntList();
IntList miniSquarePositionsY = new IntList();
int miniSquareSpeed = 9;
int miniSquareSize  = 35;

void setup () {
  size (700, 700);
  rectMode(CENTER);
}

void draw () {
  // handle keys
  if(keyPressed){
    if(key == 'w' && key != ' '){
      squareVelocityY = -squareSpeed;
    }else
    if(key == 's' && key != ' '){
      squareVelocityY =  squareSpeed;
    }
  }else{
    // reset velocity (stop square from moving)
    squareVelocityY = 0;
  }
  
  // update big square position based on velocity
  squarePositionY += squareVelocityY;
  // check if square is still on screen (reset velocity if it's not otherwise keep track of it's last 
  if (squarePositionY >= width - (squareSize * 0.5) || squarePositionY <= (squareSize * 0.5)) {
    // flip Y velocity
    squareVelocityY *= -1;
    // reset to last good known Y position
    squarePositionY = squareLastGoodY;
  }else{
    squareLastGoodY = squarePositionY;
  }
  
  // update mini squares: assumes the size of both x and y lists match
  for(int i = 0 ; i < miniSquarePositionsX.size(); i++){
    // update X position
    miniSquarePositionsX.set(i, miniSquarePositionsX.get(i) + miniSquareSpeed);
    // remove element if it's outside the screen
    if(miniSquarePositionsX.get(i) > width){
      miniSquarePositionsX.remove(i);
      miniSquarePositionsY.remove(i);
    }
  }
  // clear screen
  background (0);

  // render circle
  fill(100);
  ellipse (circleX, 140, 150, 150);
  
  // render big square
  fill (225);
  rect (squarePositionX, squarePositionY, squareSize, squareSize);
  
  // update circle position
  circleX -= 2;
  if (circleX < - 20) {
    circleX = 550;
  }
  // render mini squares: assumes the size of both x and y lists match
  for(int i = 0 ; i < miniSquarePositionsX.size(); i++){
    rect(miniSquarePositionsX.get(i), miniSquarePositionsY.get(i), miniSquareSize, miniSquareSize);
  }
}

void keyReleased(){
  // SPACE key shoot
  if(key == ' '){
    // add position entries for a mini square
    miniSquarePositionsX.append(squarePositionX);
    miniSquarePositionsY.append(squarePositionY);
    println(miniSquarePositionsY);
  }
}

如果您熟悉面向对象编程 (OOP) 基础知识，则可以使用几个类很好地封装上述内容（例如“船”的 Square 类和“子弹”的 MiniSquare 类） .玩得开心！