java - 处理(Java可视化语言): edge checking function fails when used with an array of objects

Question

我正在阅读丹尼尔·希夫曼 (Daniel Shiffman) 的优秀著作《代码的本质》(The Nature of Code)，并已完成对物体之间引力和斥力的模拟。重力效果很好，但我的物体直接飞出了屏幕。我想将它们限制在 Canvas 上。我正在使用前一章中编写的边缘检查函数，但它无法将任何对象保留在 Canvas 上。
我很想知道为什么。
有问题的函数是 Mover 类中的最后一个代码块。

class Mover {

  PVector location;
  PVector velocity;
  PVector acceleration;
  float mass;

  float G = 0.4;  //universal gravitational constant

  Mover(float m, float x, float y) {
    location = new PVector(x,y); 
    velocity = new PVector(1,0);  
    acceleration = new PVector(0,0);
    mass = m;
  }

    PVector attract(Mover m) {

      PVector force = PVector.sub(location,m.location);
      float distance = force.mag();
      distance = constrain(distance,5,25);

      force.normalize();
      float strength = ((G * mass * m.mass) / (distance * distance)*-1);
      force.mult(strength);
      return force;
  }

  void applyForce(PVector force) {
    PVector f = PVector.div(force,mass);
    acceleration.add(f);
  }

  void update() {
    velocity.add(acceleration);
    location.add(velocity);
    acceleration.mult(0);
  }

  void display() {
    stroke(0);
    strokeWeight(2);
    fill(0,100);
    ellipse(location.x,location.y, mass*25 , mass*25);
  }

  void checkEdges() {       // why doesn't this work?

    if (location.x > width) {
      location.x = width;
      velocity.x *= -1;
    } else if (location.x < 0) {
      velocity.x *= -1;
      location.x = 0;
    }

    if (location.y > height) {
      velocity.y *= -1;
      location.y = height;
    } else if (location.y < 0) {
      velocity.y *= -1;
      location.y = 0;
    }

  }

}

//////////////////////////////////////////////////////////////////////

  Mover [] movers = new Mover [10];

  void setup() {
    size(1000,1000);

    for (int i = 0; i < movers.length; i++) {
      movers[i] = new Mover(random(0.1,2),random(width),random(height)); //mass, loc.x, loc.y  //each mover initialized randomly
    }

  }

  void draw() {
    background(255);

    for(int i = 0; i < movers.length; i++){
      for(int j = 0; j < movers.length; j++){  
        if(i != j){
        PVector force = movers[j].attract(movers[i]);  //Calculate attraction force
        movers[i].applyForce(force);     //Apply attraction force
        }
      }
      movers[i].update();
      movers[i].display();
    }
  }

Answer 1

您不应该在 Update() 内调用 checkEdges() 吗？如果不是这样，那么在你的主代码之间怎么样

  movers[i].update();
  movers[I].checkEdges(); // check after the update and before the display
  movers[i].display();