用p5.js创建水

Question

我试图在p5.js中创建带有波浪和所有东西的水效果，但是我似乎无法使水中的波浪起作用。我正在掀起Michael Hoffman的this文章的浪潮。我为水创建了两个类，一个类名为“ Springs”，用于模拟水的弹簧效果，另一个类名为“ Liquid”，其中仅包含一系列弹簧和一些常数。

为了显示水，我使用了p5的beginShape（）和vertex（）函数来创建水的表面。我遍历并创建了每个弹簧高度的顶点。

现在水保持静止。我希望水只有在球碰到水面时才产生波浪。我将Liquid的“ contains”方法设置为true，只是为了查看波浪是否正在起作用。

我想知道我吸水的方式是否有问题。以前，当我单击时会有类似弹簧的效果，除了水的整个表面将保持矩形。使用向量在水中产生波浪是否有问题？似乎比Hoffman建议的绘制梯形更简单的创建波浪的方法，但是事实证明，我可以使用p5.js轻松绘制梯形。

感谢您的帮助。

代码如下：

var balls = [];

var liquid; 

function Liquid(s) {
    this.springs = s;
    this.tension = 0.025;
    this.dampening = 0.025;
    this.spread = 0.25;
}

function Spring() {
    this.targetHeight = 0;
    this.height = 0;
    this.vel = 0;

    this.update = function(dampening, tension) {
        let x = this.targetHeight - this.height;
        this.vel += (tension * x - this.vel * dampening);
        this.height += this.vel;
    }
}

Liquid.prototype.update = function () {

    for (var i = 0; i < this.springs.length; i++)
        this.springs[i].update(this.dampening, this.tension);

    var lDeltas = [];
    var rDeltas = [];

    // do some passes where columns pull on their neighbours
    for (var j = 0; j < 8; j++)
    {
        for (var i = 0; i < this.springs.length; i++)
        {
            if (i > 0)
            {
                lDeltas[i] = this.spread * (this.springs[i].height - this.springs[i - 1].height);
                this.springs[i - 1].vel += lDeltas[i];
            }
            if (i < this.springs.length - 1)
            {
                rDeltas[i] = this.spread * (this.springs[i].height - this.springs[i + 1].height);
                this.springs[i + 1].vel += rDeltas[i];
            }
        }

        for (var i = 0; i < this.springs.length; i++)
        {
            if (i > 0)
                this.springs[i - 1].height += lDeltas[i];
            if (i < this.springs.length - 1)
                this.springs[i + 1].height += rDeltas[i];
        }
    }
}

Liquid.prototype.splash = function (index, speed) {
    if (index >= 0 && index < this.springs.length)
        this.springs[i].vel = speed;
}

Liquid.prototype.display = function () {
    fill(0, 0, 255);
    beginShape();
    vertex(0, height - this.springs[0].height);
    for (var i = 0; i < this.springs.length; i++) {
        vertex(i * (width / this.springs.length), height-this.springs[i].height); //consider using the map function
    }
    vertex(width, height);
    vertex(0, height);
    endShape(CLOSE);
}

Liquid.prototype.contains = function(m) {
    return true;
};

function Mover(m, x, y) {
    this.mass = m;
    this.position = createVector(x,y);
    this.velocity = createVector(0,0);
    this.acceleration = createVector(0,0);
}

// f = m / a --> a = f / m

Mover.prototype.applyForce = function(force) {
    var f = p5.Vector.div(force,this.mass);
    this.acceleration.add(f);
}

Mover.prototype.update = function() {
    this.velocity.add(this.acceleration);
    this.position.add(this.velocity);
    this.acceleration.mult(0); //acceleration must be cleared; does not add to itself!
};

Mover.prototype.display = function() {
    stroke(0); //black outline
    strokeWeight(2); //make it more visible
    fill(255,127); //give it a gray color
    ellipse(this.position.x,this.position.y,this.mass*16,this.mass*16); //create an ellipse at the position
};

function setup() {
    createCanvas(windowWidth, windowHeight);
    background(255);
    var temp = [];
    for (var i = 0; i < 340; i++) { //340 is an arbitrary num
        var tempSpring = new this.Spring();
        tempSpring.targetHeight = height/2;
        tempSpring.height = height/2;
        temp[i] = tempSpring;
    }
    liquid = new Liquid(temp);
    liquid.display();
}

function draw() {
    background(255);
    for (var i = 0; i < balls.length; i++) {

        if(liquid.contains(balls[i])) {
            liquid.splash(balls[i].x, 0.05);
        }
        liquid.update();
        liquid.display();
        // Gravity is scaled by mass here!
        var gravity = createVector(0, 0.1*balls[i].mass);
        // Apply gravity
        balls[i].applyForce(gravity);
        balls[i].update();
        balls[i].display();


    }
    liquid.display();
}

function mousePressed() {
    balls[balls.length] = new Mover(5, mouseX, mouseY);
}

Answer 1

从哪里开始：

• 没有{42}这样的东西。
• splash（）中未定义的变量'i'。
• 您正在使用球的x坐标来索引springs数组（在splash（）内部），这似乎不正确。首先，x坐标的范围是0到宽度，并且springs数组索引的范围是0到339。其次，x坐标是一个非整数值，因此使用它对数组进行索引将无效。
• 球总是溅水
• 水不会作用在球上

找到这些东西的最佳方法是学习如何在浏览器中使用调试器，逐行浏览代码，检查所有内容，并确保它们与您的期望相符。这些简单的错误大多数都会立即跳出来。

std::initializer_list

balls[i].x

var balls = [];

var liquid;

function Liquid(s) {
  this.springs = s;
  this.tension = 0.025;
  this.dampening = 0.025;
  this.spread = 0.25;
}

function Spring() {
  this.targetHeight = 0;
  this.height = 0;
  this.vel = 0;

  this.update = function(dampening, tension) {
    let x = this.targetHeight - this.height;
    this.vel += tension * x - this.vel * dampening;
    this.height += this.vel;
  };
}

Liquid.prototype.update = function() {
  for (var i = 0; i < this.springs.length; i++)
    this.springs[i].update(this.dampening, this.tension);

  var lDeltas = [];
  var rDeltas = [];

  // do some passes where columns pull on their neighbours
  for (var j = 0; j < 8; j++) {
    for (var i = 0; i < this.springs.length; i++) {
      if (i > 0) {
        lDeltas[i] =
          this.spread * (this.springs[i].height - this.springs[i - 1].height);
        this.springs[i - 1].vel += lDeltas[i];
      }
      if (i < this.springs.length - 1) {
        rDeltas[i] =
          this.spread * (this.springs[i].height - this.springs[i + 1].height);
        this.springs[i + 1].vel += rDeltas[i];
      }
    }

    for (var i = 0; i < this.springs.length; i++) {
      if (i > 0) this.springs[i - 1].height += lDeltas[i];
      if (i < this.springs.length - 1) this.springs[i + 1].height += rDeltas[i];
    }
  }
};

Liquid.prototype.splash = function(index, speed) {
  if (index >= 0 && index < this.springs.length) this.springs[floor(index)].vel = speed;
};

Liquid.prototype.display = function() {
  fill(0, 0, 255);
  beginShape();
  vertex(0, height - this.springs[0].height);
  for (var i = 0; i < this.springs.length; i++) {
    vertex(i * (width / this.springs.length), height - this.springs[i].height); //consider using the map function
  }
  vertex(width, height);
  vertex(0, height);
  endShape(CLOSE);
};

Liquid.prototype.contains = function(m) {
  return true;
};

function Mover(m, x, y) {
  this.mass = m;
  this.position = createVector(x, y);
  this.velocity = createVector(0, 0);
  this.acceleration = createVector(0, 0);
}

// f = m / a --> a = f / m

Mover.prototype.applyForce = function(force) {
  var f = p5.Vector.div(force, this.mass);
  this.acceleration.add(f);
};

Mover.prototype.update = function() {
  this.velocity.add(this.acceleration);
  this.position.add(this.velocity);
  this.acceleration.mult(0); //acceleration must be cleared; does not add to itself!
};

Mover.prototype.display = function() {
  stroke(0); //black outline
  strokeWeight(2); //make it more visible
  fill(255, 127); //give it a gray color
  ellipse(this.position.x, this.position.y, this.mass * 16, this.mass * 16); //create an ellipse at the position
};

function setup() {
  createCanvas(windowWidth, windowHeight);
  background(255);
  var temp = [];
  for (var i = 0; i < 340; i++) {
    //340 is an arbitrary num
    var tempSpring = new Spring();
    tempSpring.targetHeight = height / 2;
    tempSpring.height = height / 2;
    temp[i] = tempSpring;
  }
  liquid = new Liquid(temp);
  liquid.display();
}

function draw() {
  background(255);
  liquid.update();
  liquid.display();

  for (var i = 0; i < balls.length; i++) {
    var ball = balls[i];

    if (liquid.contains(ball)) {
      liquid.splash(ball.position.x, 54.5);
    }
    //liquid.display();
    // Gravity is scaled by mass here!
    var gravity = createVector(0, 0.1 * ball.mass);
    // Apply gravity
    ball.applyForce(gravity);
    ball.update();
    ball.display();
  }
}

function mousePressed() {
  balls[balls.length] = new Mover(5, mouseX, mouseY);
}